DE102017118528A1 - Method for producing a blank for the production of dental components by means of subtractive CAD / CAM methods - Google Patents

Abstract

A method is described for producing a blank for the production of dental components by means of subtractive CAD / CAM methods or for producing a dental component from such a blank. The present invention also relates to a metallic blank for the manufacture of dental components by means of a subtractive CAD / CAM method. The present invention further relates to the use of a corresponding blank when manufacturing dental components by means of subtractive CAD / CAM methods to increase the service life of the tool used in the subtractive CAD / CAM method. The present invention also relates to the use of a heat treatment in the manufacture of a high workability ingot for the fabrication of dental components by subtractive CAD / CAM techniques, a kit for manufacturing dental devices by CAD / CAM milling, and the use of an electrochemical process in cleaning and / or smoothing a blank for the production of dental components by means of subtractive CAD / CAM methods.

Description

The present invention as well as preferred embodiments thereof are defined in the appended claims and the present description. It relates to a method for producing a blank for the production of dental components by means of subtractive CAD / CAM methods or for producing a dental component from such a blank. The present invention also relates to a metallic blank for the manufacture of dental components by means of a subtractive CAD / CAM method. The present invention further relates to the use of a corresponding blank when manufacturing dental components by means of subtractive CAD / CAM methods to increase the service life of the tool used in the subtractive CAD / CAM method. The present invention also relates to the use of a heat treatment in the manufacture of a high workability ingot for the fabrication of dental components by subtractive CAD / CAM techniques, a kit for manufacturing dental devices by CAD / CAM milling, and the use of an electrochemical process in cleaning and / or smoothing a blank for the production of dental components by means of subtractive CAD / CAM methods.

Dental components, such as, for example, dental prosthesis parts or dental auxiliary parts, can in principle be produced in a technically complicated and cost-intensive method in the dental laboratory using the lost-wax technique.

However, the dental components produced by this process often have typical casting defects such as voids, porosities or inhomogeneities, which can result in adverse mechanical properties.

As an alternative to the lost wax process, subtractive, i. Material-removing, CAD / CAM (CAD: "computer-aided design", CAM: "computer-aided manufacturing"), such as CAD / CAM milling process, established for the production of dental components. In this case, the dental components are subtractive out, usually cylindrical or cuboidal, blanks worked out, in addition to blanks made of dental ceramics and metallic blanks, in particular blanks of dental alloys such as cobalt-chromium alloys are used.

A comprehensive insight into the technical field, especially concerning the production of metallic blanks, is provided by the textbook "Material Science of Dental Materials 1" by R. Strietzel, (2016, Verlag Neuer Merkur GmbH, ISBN: 978-3-95409-037-2) , Blanks made of metallic materials can be produced either by casting or powder metallurgy. The most common way to make metal blanks is by casting large ingots, which are removed from the mold after casting and drawn to the desired diameter of the blank. The large ingots obtained are separated by suitable separation processes, ie separated into slices of a desired thickness. Alternatively, slices of the desired thickness can also be cast directly or powder metallurgically, usually using hot isostatic pressing (HIP process, cf. DE 102005045698 A1 ) getting produced. However, the discs are then treated by machining the workpiece surface, eg by turning or milling, prior to further processing at the top and bottom to obtain parallel and clean surfaces and to precisely set the desired dimensions (in particular height) of the blanks. where the exact height adjustment is not only technically necessary, but also for reasons of "consumer compliance" is advantageous.

A basic overview of the technical field is also given by J. Lindigkeit in his article "Goodbye? Precious metal-free dental materials in the CAD / CAM era "in quintessence Zahntech 2006; 32 (9): 1012-1019 and B. Karpuschewski et al. in her article "CoCr Is Not the Same: CoCr Blanks for Dental Machining" in G-shoe el al. (eds.), "Future Trends in Production Engineering" (DOI 10.1007 / 978-3-642-24491-9_26, Springer-Verlag Berlin Heidelberg 2013) ,

The document EP 1972322 B1 relates, according to its independent claim, to a method for producing a metal tooth reconstruction, such as a framework, using a cobalt-chromium alloy having a specific composition.

The document DE 102013003434 A1 concerns according to its independent claim a milling blank for the production of dental prosthesis parts by means of CAD / CAM method, which is characterized by a specific composition.

The document DE 10342231 A1 concerns according to its independent claim a blank for the production of dental prostheses, having a sufficient strength for a material-removing machining in a processing machine, characterized in that the blank has a porous framework structure having infiltrierbare cavities.

The document DE 19714178 A1 relates to a method according to its independent claim for producing a multicolored shaped body for further processing into dental restorations, characterized in that at least two differently colored starting materials are introduced into a pressing die which essentially predetermines the shape of the shaped body and pressed into the shaped body, and a device for carrying out a corresponding method.

The document DE 10309795 A1 concerns according to its independent claim a method for the production of a tooth replacement part from metallic materials, characterized in that a formed from a metal-containing powder mixture and solidified blank is provided, and that in a second step from the blank an intermediate body is produced, and that in a third Step after treatment of the intermediate body takes place, with which the desired material properties of the dental prosthesis part can be achieved.

The document EP 1764062 B1 concerns according to its independent claim a method for the production of a shaped body which consists of a dental alloy and is machinable for the production of dental parts, wherein a dental alloy powder by hot isostatic pressing densely sintered, characterized in that the dental alloy powder from a melt of a dental alloy by means of atomizing manufactures. Basic information on the production of workpieces by powder metallurgy methods can also be found in the WO 0207911 A1 ,

Information on electrochemical processes for the surface treatment of workpieces can be found, for example, in WO 2013167905 , at K. Nestler et al, Procedia CIRP 42 (2016) 503-507 , at Zeidler et al, Procedia CIRP 49 (2016) 83-87 , in DE 202008011646 U1 , in the "Handbook" by U. Heisel et al. (Karl Hanser Verlag Munich, 2014, pages 1228 ff ) as well as in the lecture of H. Zeidler et al. "Use of additive manufacturing processes and plasma electrolytic surface treatment in medical technology", held at the Biosaxony "Medizintechnik in Sachsen", Chemnitz 2016 ,

Basic investigation results on the machinability of commercially available CoCr blanks were obtained, for example, from R. Riquier and M. Krause in Quintessence Zahntech 2011; 37 (5): 628-639 released.

It is known that metallic blanks, in particular blanks made of cobalt-chromium alloy, are often machinable only with comparatively high use of tools. Therefore, metallic blanks are often difficult to machine even with subtractive (cutting) CAD / CAM techniques. This corresponds to long processing times and high wear of the tools used, i. low tool life.

The present invention is based on the primary object of providing metallic blanks which can be machined better by machining methods, in particular by subtractive (cutting) CAD / CAM methods, by the disadvantages described above, in particular the high tool wear during machining to eliminate or at least alleviate. Accordingly, the present invention is also based on the object to provide a method for producing a blank for the production of dental components by means of subtractive CAD / CAM method, which has a particularly good workability with cutting (CAD / CAM) manufacturing processes, the Method is particularly flexible in terms of the production of the blank underlying metallic workpieces. Accordingly, the present invention is also based on the object of specifying a method for producing a dental component by means of subtractive CAD / CAM method, which is characterized by a reduced mechanical load and correspondingly longer service life of the tools used and thereby enables cost-effective production in large quantities , This object is closely linked to the additional task of specifying a method for producing a dental component by means of subtractive CAD / CAM methods, in which the working and process safety is particularly high, while at the same time reducing the amount of waste produced, in the form of worn tools becomes.

The present invention should preferably make it possible to extend the service life of milling cutters, preferably of roughing cutters, preferably of toroidal cutters with corner radius and / or radius milling cutters (ball endmills), particularly preferably torus cutters, which are used during machining. Milling with a roughing cutter (also called roughing) is about removing a large volume of material as effectively and quickly as possible. In this case, a contour is traversed, which represents an allowance for the final contour.

In addition, the present invention is also based on the further object of ensuring that the blanks produced or to be specified meet the technical requirements with respect to the surface finish, which result from the intended use of the blanks and from the need for reliable quality assurance, in particular by necessity the visual inspection of the blanks.

From the foregoing, it can be seen that the present invention is also based on the further object of using a blank having good machinability with machining methods in the manufacture of dental components by subtractive CAD / CAM techniques to increase the lifetime of the subtractive CAD / CAM. Specify the CAM method of the tool used.

Moreover, the present invention is also based on the further object of specifying a kit for producing dental components by means of CAD / CAM milling methods.

Further objects emerge from the following description and the claims.

The above objects are achieved by methods, metallic blanks, kits and uses as defined in the appended claims. Preferred embodiments of the invention will become apparent from the dependent claims.

1. a) Herstellen eines Rohlings aus einem metallischen Werkstück durch zerspanende Bearbeitung von zumindest Bereichen der Werkstückoberfläche oder Bereitstellen eines solchen Rohlings, wobei die Oberflächenhärte des hergestellten oder bereitgestellten Rohlings höher ist als seine Kernhärte und die zerspanende Bearbeitung ausgewählt ist aus der Gruppe bestehend aus Drehen, Schleifen und Fräsen,
2. b) Wärmebehandeln des in Schritt a) hergestellten oder bereitgestellten Rohlings, so dass zumindest die Oberflächenhärte des hergestellten oder bereitgestellten Rohlings reduziert wird.

In particular, the present invention relates to a method for producing a blank for the production of dental components by means of subtractive CAD / CAM methods or for producing a dental component from such a blank, comprising the steps:

1. a) producing a blank from a metallic workpiece by machining at least portions of the workpiece surface or providing such a blank, wherein the surface hardness of the prepared or prepared blank is higher than its core hardness and the machining is selected from the group consisting of turning, grinding and milling,
2. b) heat treating the blank produced or provided in step a) so as to reduce at least the surface hardness of the blank produced or provided.

Blanks for the production of dental components by means of subtractive CAD / CAM methods are usually produced from metal workpieces by machining, in particular turning, grinding and milling, at least areas of the workpiece surface, the machining especially the adjustment of the exact dimensions required, in particular Height of the blanks, serves. The corresponding height adjustment is inevitably required from a technical point of view for many reasons, in particular to guarantee the accuracy of fit of the blanks in the proposed machine tools and the error-free automated packaging of the blanks before distribution.

In accordance with surface-treated blanks shows a particularly poor processability with machining processes, such as subtractive CAD / CAM process, in particular milling process, even in comparison with the inherently anyway quite poor machinability of metallic materials in corresponding procedures. The inventors have recognized in their own experiments that the further deteriorated machinability according to surface-processed blanks is due to the machining of the workpiece surface, as explained above, particularly by turning, grinding and milling. According to our own investigations, the hardness in the area of the machined workpiece surface is disadvantageously increased. Unfortunately, there is currently no practical alternative in the height adjustment to the machining of the workpiece surface, which could be usefully used under ecological, economic and procedural aspects.

It has been shown in own investigations that the negative effects of machining on the resulting blank can be reduced and in many cases almost eliminated if the blank obtained from a metal workpiece by machining at least portions of the workpiece surface, is subjected to a heat treatment, so that at least the hardness of the blank in the area of the machined surface is reduced. It is believed that by heat treating, stresses within the blank and thus the solidification at the surface can be broken down. In addition, the heat treatment also allows adjustment of the mechanical properties of the blank by several mechanisms (such as setting certain phases, eg cubic co-phase (fcc)), removing dislocations, dissolving precipitates, and controlling grain growth ,

According to the invention, by the step of producing a blank from a metallic workpiece by machining of at least areas of the workpiece surface (step (a) according to the invention), a surface is provided or prepared which (after carrying out the heat treatment and optionally after carrying out further steps) by means of subtractive CAD / CAM procedure to be processed.

By the method according to the invention are surprisingly blanks with a obtained particularly good workability. It has been found that, in particular, the surface hardness (for the meaning of the term, see the remarks below) of the blanks, which is particularly adversely affected by the machining (step (a) according to the invention), by the heat treatment (step (b) according to the invention). is particularly positively influenced. This is particularly advantageous because in subtractive CAD / CAM processes, in particular, the surface and the near-surface layers of the blanks are typically processed.

Accordingly, it has surprisingly been found in our own experiments that the method steps according to the invention are advantageous because in this way the tool wear is reduced and the service life of the tool (a measure of the time until the tool is closed) can thus be significantly increased. This means that it is advantageous if a blank obtained from a metallic workpiece by machining is subjected to a corresponding heat treatment before machining by means of subtractive CAD / CAM methods.

Blanks for the production of dental components by means of subtractive CAD / CAM methods are known to the person skilled in the art. In the context of the present application, such a blank is understood to mean an article which is suitable or prepared for the production of dental components by means of subtractive CAD / CAM methods and which can be machined, in particular by machining, and, if appropriate, suitable aftertreatment such as, for example, cleaning, obtained from a metallic workpiece. Thus, the blank is at least partially metallic. Preferably, the blank is completely metallic, i. it is made entirely of metal. However, the person skilled in the art is aware that a corresponding blank and / or the blank underlying the blank can also have non-metallic constituents, such as, for example, superficial oxide layers or intentionally introduced, non-metallic phases, such as ceramic additives, and nevertheless within the meaning of the present invention Registration is metallic. In case of doubt, a blank and / or the blank underlying the workpiece is at least metallic if it consists of more than 50 wt.% Of metallic components, based on the total mass of the blank or the workpiece.

Dental components in the sense of the present application are components which are intended for use in the human or animal oral cavity, in particular dental crowns, partial crowns, inlays, onlays, bridges and other dental restorations or prostheses and dental auxiliary parts.

Subtractive CAD / CAM methods are known to the person skilled in the art. The abbreviations stand for "computer-aided design" (CAD) and "computer-aided manufacturing" (CAM). CAD, Computer-aided Design, refers to the support of design tasks by means of EDP for the production of a product. CAM, Computer-Aided Manufacturing, refers to the use of machine-independent software to create input for automated manufacturing, as opposed to manual creation. Subtractive CAD / CAM processes are characterized by the fact that, unlike additive CAD / CAM processes such as selective laser melting (SLM), material is removed from a workpiece to produce the desired product receive. Examples of subtractive CAD / CAM methods are in particular CAD / CAM milling methods, CAD / CAM grinding methods and CAD / CAM turning methods. With the method according to the invention, blanks are produced which are suitable for the production of dental components by means of subtractive CAD / CAM methods, or dental components are produced from such a blank, preferably by means of a subtractive CAD / CAM method (see below).

For the purposes of the present text, the term surface (also as part of "workpiece surface" and "surface hardness") accordingly in the context of the respective technical explanations regularly the outer, visible surfaces of the blank or the workpiece on which in the steps (a ) and (b) following the subtractive CAD / CAM process actually a processing of the blank takes place or should take place. Using the example of a typical disc-shaped blank, this means that the term surface in the context of the respective technical explanations designates the outer, visible surface of the upper side and lower side (on which the blank is typically processed in the subtractive CAD / CAM process), but not the lateral surface. This understanding of the term is meaningful for the person skilled in the art, since only the properties of the subsequently actually machined surfaces are of relevance for the performance of the blank in the subtractive CAD / CAM method, whereas the lateral surfaces are regularly used for marking the blanks or for advertising purposes. This means, in particular, that the production of a blank from a metallic workpiece takes place by machining at least regions of the workpiece surface, wherein the said regions of the workpiece surface are to be further processed later in the subtractive CAD / CAM method. For example, a machining would be exclusive of the lateral surfaces of a disc-shaped metallic Workpiece for setting the circle diameter, wherein the lateral surfaces are not to be processed by means of subtractive CAD / CAM process, no helpful preparation in the sense of the present tasks. According to the invention, it is advantageous to prepare a surface for machining by means of subtractive CAD / CAM processes by machining at least regions of the workpiece surface in step (a) and reducing the surface hardness (the hardness of the previously prepared surface) in step (b) ,

In the context of the present application, the term hardness always refers to the Vickers hardness according to DIN EN ISO 6501-1 "Metallic materials". The hardness test is carried out according to the test method according to DIN EN ISO 6507-1: 2006 combined with DIN EN ISO 6507-4: 2006 "Part 4: Tables for the determination of hardness values", using the test load of 10 kiloponds (HV 10).

Taking into account the above, the surface hardness of the blank indicates the Vickers hardness as measured on the outer, visible surfaces of the blank on which the blank is actually machined in the subtractive CAD / CAM method. If different hardnesses are measured along a relevant surface and / or between the different relevant surfaces, for example top and bottom, the surface hardness is determined as the arithmetic mean of 20 measuring points distributed uniformly over the entire surface.

It is understood that in preferred blanks according to the invention or corresponding workpieces, the center of gravity lies within the blank or workpiece; they are typically symmetrical, solid and largely homogeneous bodies. The core hardness is then the Vickers hardness (see above) determined at the center of mass of the blank or workpiece, the determination being made in the blank of the blank or workpiece, i. takes place at the divided by the center of gravity through blank or workpiece. Should exceptionally (and this is not preferred in the present invention) the center of gravity not be within the blank or workpiece because the blank or workpiece has an unusual shape, the core hardness must be determined at a point that is the center of a coordinate system along each possible one Axis to the outer surfaces of the blank or core most likely to have the same distance.

While the surface hardness can be determined directly on the surface of the blank, the following steps are usually performed before measuring the core hardness: centering, preferably sawing, the blank; Grinding and / or polishing one of the two surfaces produced by the parts with low contact pressure, so that it does not increase the hardness,

Machining is also referred to as machining or machining and is the collective term for a group of manufacturing processes that give workpieces a specific geometric shape by removing excess material mechanically from chips in the form of chips. According to the invention, the machining is selected from the group consisting of turning, grinding and milling. These methods are known to the person skilled in the art.

The heat treatment of the prepared or prepared blank in accordance with the method according to the invention is, in the context of the present application, a method step following step (a) in which conditions are set under which heat is applied to the blank. The produced or prepared blanks are preferably exposed for a period of at least a few minutes (preferably at least 15 minutes) to a temperature which is preferably at least 40% of the solidus temperature in ° C. This means, for example, that in the case of a CoCr alloy according to the attached example (solidus temperature: 1380 ° C.), heating for a maximum of 10 minutes and / or heating to a temperature below, for example, 552 ° C. (ie 40% of 1380 ° C.) ) is preferably not spoken of a heat treatment in the sense of the present application. The heat treatment in step (b) is not accompanied by machining, e.g. in the subsequent step of a subtractive CAD / CAM treatment, but is also a separate step in this respect (see below for preferred embodiments). In particular, any increase in temperature, which may occur in the course of machining (in particular step (a)) or a subtractive CAD / CAM process (in a subsequent step), does not constitute heat treatment in the sense of the present application.

In the method according to the invention, in step a) the production of a blank from a metallic workpiece by machining at least regions of the workpiece surface in preference to the provision of such a blank is preferred.

• wobei der Rohling nach Schritt b) bevorzugt einen Quotienten Oberflächenhärte zu Kernhärte aufweist, der kleiner ist als 1,2; bevorzugt kleiner ist als 1,1; besonders bevorzugt kleiner ist als 1,05.

A method according to the invention is preferred (preferably as described above as preferred), wherein in step b) the ratio of surface hardness to core hardness is reduced,

• wherein the blank after step b) preferably has a quotient surface hardness to core hardness which is less than 1.2; preferably less than 1.1; more preferably less than 1.05.

Correspondingly preferred processes are particularly advantageous because blanks are obtained with these processes whose surface properties, in particular their surface hardness, are particularly similar to the corresponding core properties. Advantageously, it has been found that the quotient of surface hardness to core hardness is a suitable measure for quantifying the extent of the increase in machinability. This means that the disadvantageous properties resulting from the machining operation are particularly markedly reduced in preferred processes according to the invention and that a particularly high processability of the produced blanks results.

The quotient surface hardness to core hardness in the sense of the present application is a dimensionless quantity which is obtained when the surface hardness of a blank is divided by the core hardness of this blank, wherein the surface hardness and the core hardness are defined as explained above.

• wobei das Spannungsarmglühen vorzugsweise bei einer Temperatur im Bereich von 50 bis 70 % der in °C angegebenen Solidustemperatur erfolgt, wobei die Temperatur vorzugsweise so gewählt wird, dass es im Rohling nicht zu einer Phasentrennung kommt (mit anderen Worten: das Spannungsarmglühen erfolgt bei einer Temperatur im Bereich von 50 bis 70 % der der in °C angegebenen Solidustemperatur, wobei diese Art der Temperaturbehandlung erfindungsgemäß bei Legierungen verwendet wird, bei denen es in diesem Temperaturbereich nicht zu einer Phasentrennung kommt) und
• wobei das Lösungsglühen vorzugsweise bei einer Temperatur oberhalb, bevorzugt um mehr als 50 °C oberhalb, besonders bevorzugt um mehr als 100 °C oberhalb, der Phasenumwandlungstemperatur der Umwandlung von der hexagonalen Packung zur kubischen Packung und bei einer Temperatur unterhalb, bevorzugt um mehr als 100 °C unterhalb, besonders bevorzugt um mehr als 150 °C unterhalb, ganz besonders bevorzugt um mehr als 200 °C unterhalb der Solidustemperatur erfolgt,
  • wobei die Phasenumwandlungstemperatur die Temperatur ist, bei der es zur Phasenumwandlung der Primärphase des Rohlings kommt, und die Solidustemperatur die Temperatur ist, bei der es zum Aufschmelzen der Phase mit dem niedrigsten Schmelzpunkt im Rohling kommt
• und/oder
• wobei in Schritt b) das Wärmebehandeln bei einer Temperatur im Bereich von 950 °C bis 1300 °C, bevorzugt im Bereich von 1000 °C bis 1250 °C, erfolgt
• und/oder
• wobei in Schritt b) das Wärmebehandeln bei einem Druck von weniger als 5 MPa, bevorzugt weniger als 0,5 MPa, erfolgt
• und/oder
• wobei in Schritt b) das Wärmebehandeln, vorzugsweise das Wärmebehandeln bei der maximalen Behandlungstemperatur, für eine Dauer im Bereich von 15 bis 240 Minuten, bevorzugt im Bereich von 30 bis 180 Minuten, besonders bevorzugt im Bereich von 45 bis 120 Minuten, erfolgt
• und/oder
• wobei nach Schritt b) (vorzugsweise beim Lösungsglühen, siehe oben) ein Abkühlen des Rohlings innerhalb von weniger als 20 Minuten, bevorzugt innerhalb von weniger als 10 Minuten, besonders bevorzugt innerhalb von weniger als 5 min, auf eine Temperatur erfolgt, die, gemessen im Massenschwerpunkt des Rohlings, unter 50% der in °C angegebenen Solidustemperatur liegt, bei einem Rohling mit den Hauptbestandteilen Cobalt und Chrom bevorzugt bei unter 700 °C liegt,
• und/oder
• wobei in Schritt b) das Wärmebehandeln des Rohlings und/oder nach Schritt b) ein Abkühlen des Rohlings in einem Inertgasstrom oder im Vakuum erfolgt,
  • wobei vorzugsweise das Inertgas ausgewählt ist aus der Gruppe bestehend aus Stickstoff, Helium Argon und deren Mischungen.

A method according to the invention is preferred (preferably as described above as preferred),
wherein in step b) the heat treatment is carried out by stress relief annealing or solution annealing, preferably by solution annealing,

• wherein the stress relief annealing is preferably carried out at a temperature in the range of 50 to 70% of the solidus temperature indicated in ° C, the temperature preferably being chosen so that there is no phase separation in the blank (in other words stress relief annealing occurs at a temperature in the range of 50 to 70% of the solidus temperature given in ° C, this type of temperature treatment being used according to the invention for alloys which do not phase separate in this temperature range) and
• wherein solution heat treatment is preferably at a temperature above, preferably greater than 50 ° C above, more preferably greater than 100 ° C above, the phase transition temperature of the hexagonal packing to cubic packing conversion and at a temperature below, preferably greater than 100 ° C. below, more preferably by more than 150 ° C. below, very particularly preferably by more than 200 ° C. below the solidus temperature,
  • wherein the phase transition temperature is the temperature at which phase transition of the primary phase of the blank occurs, and the solidus temperature is the temperature at which melting of the lowest melting point phase in the blank occurs
• and or
• wherein in step b) the heat treatment at a temperature in the range of 950 ° C to 1300 ° C, preferably in the range of 1000 ° C to 1250 ° C, takes place
• and or
• wherein in step b) the heat treatment is carried out at a pressure of less than 5 MPa, preferably less than 0.5 MPa
• and or
• wherein in step b) the heat treatment, preferably the heat treatment at the maximum treatment temperature, for a duration in the range of 15 to 240 minutes, preferably in the range of 30 to 180 minutes, particularly preferably in the range of 45 to 120 minutes
• and or
• wherein after step b) (preferably in the solution heat treatment, see above) cooling of the blank within less than 20 minutes, preferably within less than 10 minutes, more preferably within less than 5 minutes, to a temperature which, measured in Center of gravity of the blank, below 50% of the stated in ° C solidus temperature is, in a blank with the main components cobalt and chromium preferably below 700 ° C,
• and or
• wherein in step b) the heat treatment of the blank and / or after step b) a cooling of the blank takes place in an inert gas stream or in a vacuum,
  • wherein preferably the inert gas is selected from the group consisting of nitrogen, helium argon and mixtures thereof.

Correspondingly preferred methods are particularly advantageous because the corresponding embodiments of the heat treatment have been found to be particularly advantageous in own investigations and the heat treatment in step b) leads to a particularly rapid and / or pronounced improvement in the workability of the blanks.

Particularly preferred is a preferred method according to the invention, in which at least two, preferably at least three, more preferably all of the above-mentioned features or embodiments are realized.

The temperature ranges in stress relieving or solution annealing given as a function of the solidus temperature and the phase transformation temperature of the conversion from the hexagonal packing to the cubic packing, also referred to below as the phase transformation temperature, have proven to be particularly efficient when using a metallic blank whose physical-chemical properties are adequate are well known.

The phase transition temperature is in the context of the present invention and with a suitable selection of the blank preferably the phase transition temperature of the metallic primary phase of the blank, so the metallic phase of the blank with the largest mass fraction on the blank, i. that any non-metallic phases present are not taken into account in the calculation. The solidus temperature in the context of the present invention and with a suitable selection of the blank is preferably the temperature at which melting of the phase with the lowest melting point in the blank occurs.

Basically, the solidus temperature indicates the temperature of a material at and below which the material is completely in solid phase and the phase transition temperature is the temperature at which the metallic phase converts from the hexagonal packing to the cubic packing.

Preferably, the temperature is selected during stress relief annealing so that there is no disadvantageous phase separation in the blank. The person skilled in the art also speaks of the formation of precipitates in the case of such a phase separation.

The absolute temperature specification given above as preferred has proved in own experiments as a kind of universal temperature range in which at least sufficient effects can be achieved for almost all metallic blanks, even if the actual composition and the physico-chemical properties of the material used are not sufficiently known are.

The pressures and treatment times defined above have proven to be correspondingly advantageous. The pressure takes into account both any pressure on the blank both by mechanical load and by the prevailing gas pressure. The duration of the heat treatment is measured in the context of the present application from the time at which the surface of the blank, the maximum treatment temperature, i. having the temperature set for the heat treatment.

It is particularly advantageous if, after step b) (preferably during solution heat treatment, see above), the blank is cooled rapidly to a temperature which, measured in the center of gravity of the blank, is 250 ° C. or more below the phase transition temperature of the metallic phase of the blank ,

With respect to the center of mass of the blank and the phase transformation temperature of the metallic phase, the above statements apply.

As a result of the rapid cooling, it is advantageously completely or at least partially prevented that metallic phases formed in the blank in the course of the heat treatment with favorable mechanical properties are re-formed on cooling. In addition, this advantageously reduces or avoids the formation of an oxide or tarnish layer on the surface of the blank.

The performance of the heat treatment and / or the subsequent cooling in an inert gas stream or in a vacuum, i. at a pressure which is smaller than the respective prevailing ambient pressure is advantageous, since this can prevent the formation of an oxide or tarnish layer on the surface of the blank. Accordingly, processes according to the invention are preferred, wherein in step b) the heat treatment of the blank and, after step b), the blank is cooled in an inert gas stream or in vacuo.

Preference is given to a process according to the invention (preferably as described above as being preferred), wherein the blank after step b), preferably both after step a) and after step b), has on the surface an arithmetic mean roughness R _a which is less than 3 , 2 μm, preferably less than 1.6 μm.

Correspondingly preferred methods are particularly advantageous since particularly smooth blanks are obtained, which are very advantageous. In particular, a smooth surface of the blanks allows a person skilled in the art to more easily judge the integrity and quality of the blank, eg visually. The low arithmetic mean roughness R _a corresponds to a low microscopic surface and thereby advantageously minimizes the susceptibility of the blank to the formation of oxide or tarnish layers and increases the stability chemical stress. The inventive method is particularly advantageous because the low surface roughness achieved by the machining in step a) is not or only slightly affected by the heat treatment.

The arithmetic mean roughness R _a is known to the person skilled in the art as size and is defined in EN ISO 4287: 2010.

• - Gießen einer Metallschmelze zu der Scheibe oder einem Vorkörper,
• - Heraustrennen der Scheibe aus einem Vorkörper, vorzugsweise durch ein trennendes Fertigungsverfahren ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden,
• - Druckumformen der Scheibe oder eines Vorkörpers, vorzugsweise Schmieden oder Walzen,
• - Formen der Scheibe durch Gießen einer Metallschmelze und Druckumformen, vorzugsweise Schmieden oder Walzen, des resultierenden Gussstücks,
• - Formen der Scheibe durch Gießen einer Metallschmelze zu einem Vorkörper und Heraustrennen der Scheibe aus dem Vorkörper, vorzugsweise durch ein trennendes Fertigungsverfahren ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden,
• - Formen der Scheibe durch Gießen einer Metallschmelze zu einem Vorkörper, Druckumformen des Vorkörpers, Heraustrennen der Scheibe aus dem druckumgeformten Vorkörper, wobei das Druckumformen vorzugsweise ein Schmieden oder Walzen ist, wobei das Heraustrennen vorzugsweise ein trennendes Fertigungsverfahren ist ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden,
• - Formen der Scheibe durch Gießen einer Metallschmelze zu einem Vorkörper, Heraustrennen der Scheibe aus dem Vorkörper und Druckumformen der Scheibe, wobei das Druckumformen vorzugsweise ein Schmieden oder Walzen ist, wobei das Heraustrennen vorzugsweise ein trennendes Fertigungsverfahren ist ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden und
• - Formen der Scheibe durch pulvermetallurgisches Erzeugen eines Vorkörpers, vorzugsweise durch heißisostatisches Pressen von Pulver, und Heraustrennen der Scheibe aus dem Vorkörper, wobei das Heraustrennen vorzugsweise ein trennendes Fertigungsverfahren ist ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden.

Preference is given to a method according to the invention (preferably as described above as preferred), wherein the metallic workpiece used in step a) is a disc, the method for its production comprising one or more steps or step combinations selected from the group consisting of :

• Casting a molten metal to the disk or preform,
• Separating the disc from a preform, preferably by a separating manufacturing method selected from the group consisting of sawing, wire EDM, laser cutting and water jet cutting,
• Pressure forming of the disc or a preform, preferably forging or rolling,
• Shaping the disc by casting a molten metal and pressure forming, preferably forging or rolling, the resulting casting,
• Shaping the pane by casting a molten metal into a preform and separating it out of the preform, preferably by a separating manufacturing process selected from the group consisting of sawing, wire eroding, laser cutting and water jet cutting,
• Forming the disk by casting a molten metal into a preform, pressure forming the preform, separating the disk from the pressure-formed preform, wherein the pressure forming is preferably forging or rolling, the separation preferably being a separating manufacturing process selected from the group consisting of saws, Wire EDM, laser cutting and water jet cutting,
• Forming the disk by casting a molten metal into a preform, separating the disk from the preform, and pressure forming the disk, wherein the pressure forming is preferably forging or rolling, wherein the severing is preferably a parting manufacturing process selected from the group consisting of sawing, wire eroding , Laser cutting and water jet cutting and
• Forming the disc by powder metallurgy producing a preform, preferably by hot isostatic pressing of powder, and separating out the disc from the preform, wherein the separating is preferably a separating manufacturing method selected from the group consisting of sawing, wire EDM, laser cutting and water jet cutting.

Correspondingly preferred methods are particularly advantageous since correspondingly produced metal workpieces often have a microstructure or a microstructure due to their production, whose mechanical properties, in particular surface properties, can be influenced particularly strongly by the machining of at least areas of the workpiece surface, which is at least some Cases probably due to the good compressibility, solidifiability or hardenability of these workpieces. Since the influence of machining in preferred processes is therefore often particularly disadvantageous, the improvement to be achieved absolutely by the heat treatment provided according to the invention is advantageously particularly pronounced.

The method according to the invention is particularly advantageous for workpieces in the form of disks, because disks have a relatively large surface area to volume ratio and are therefore particularly strongly hardened by the mechanical processing, but at the same time the heat treatment of the entire disk is particularly effective, as in slices no pronounced thermal gradients arise.

Such preferably to be used metallic workpieces can be summarized either directly produced as discs or obtained from a preform previously prepared by singulation. Both the discs (in direct production) and the preforms can be produced either by casting or powder metallurgy. Both the discs (in direct production) and the preforms can optionally be pressure-processed, regardless of the method of manufacture.

Methods for separating (eg sawing, wire eroding, laser cutting or water jet cutting) and pressure forming (forging or rolling) are known in the art. The pressure forming of the disks or preforms is preferred because it can reduce the porosity and grain size in the disks or the preforms, thereby reducing the mechanical properties Chemical resistance and susceptibility to hardening during machining can be favorably influenced.

• wobei die elektrochemischen Verfahren vorzugsweise ausgewählt sind aus der Gruppe bestehend aus Beschichten, Elektropolieren und Plasmapolieren, besonders bevorzugt Elektropolieren und Plasmapolieren, ganz besonders bevorzugt Plasmapolieren,
• wobei die chemischen Verfahren vorzugsweise ausgewählt sind aus der Gruppe bestehend aus Beschichten und Beizen und
• wobei die mechanischen Verfahren vorzugsweise ausgewählt sind aus der Gruppe bestehend aus Beschichten, Bürsten, Polieren und Schleifen.

Preferred is a method according to the invention (preferably as referred to above as preferred), additionally comprising after step b) the step to ensure the quality and / or to facilitate the visual inspection of the quality of the surface of the blank
c) treating the surface of the blank with one or more methods selected from the group consisting of electrochemical processes, chemical processes, mechanical processes and combinations thereof, preferably electrochemical processes,

• wherein the electrochemical processes are preferably selected from the group consisting of coating, electropolishing and plasma polishing, more preferably electropolishing and plasma polishing, very particularly preferably plasma polishing,
• wherein the chemical processes are preferably selected from the group consisting of coating and pickling and
• wherein the mechanical methods are preferably selected from the group consisting of coating, brushing, polishing and grinding.

Correspondingly preferred methods are particularly advantageous since blanks made in accordance with this can be checked particularly easily for the required quality by the person skilled in the art. A correspondingly surface-treated surface is used, for example by a special degree of purity or a specific coating, as a kind of quality seal, which allows the skilled person, even under visual control, to recognize whether the blank should be discarded or used.

The removal of oxide and / or tarnish layers is from a technical point of view particularly important because the skilled person can not judge the depth of a corresponding, opaque layer and often has to assume that the blank has a large area unusable in the presence of a corresponding layer for reasons of quality is. This can be avoided in the preferred process, wherein a coating has a special but ultimately analogous meaning, since the skilled person trusts the manufacturer / coater and the quality of the blank in view of an unbroken and undamaged coating.

This advantageous aspect is particularly advantageous for the method according to the invention because the heat treatment of the blanks promotes the formation of oxide and / or tarnish layers on the surface of the blank in a particular case.

On the basis of own experiments, the surface treatment methods specified above were selected specifically according to which they do not again negate the advantages of better machinability achieved in the method according to the invention, as would be the case, for example, for otherwise frequently used turning.

However, as a result of the fact that a certain basic surface smoothness has been produced by the machining before the heat treatment, it is generally sufficient to use the surface treatment methods given here only very briefly and with little intensity, since they essentially have a cleaning function and less a smoothing function.

• - der erfindungsgemäß vorgesehenen zerspanenden Bearbeitung in Schritt a) (deren Nachteile in Schritt b) ausgeglichen und deren Vorteile in Schritt c) genutzt werden),
• - der erfindungsgemäß vorgesehenen Wärmebehandlung (deren Vorteile die Nachteile des Schrittes a) ausgleichen und deren gelegentlich auftretende Probleme von Schritt c) gelöst werden) und
• - der erfindungsgemäß bevorzugten Oberflächenbehandlung in Schritt c) (die von Schritt a) profitiert, ggf. auftretende Probleme des Schrittes b) löst und die Vorteile des Schrittes b) nicht zerstört).

This results in a synergistic interaction

• the machining according to the invention provided in step a) (whose disadvantages are compensated in step b) and whose advantages are used in step c),
• the heat treatment provided according to the invention (the advantages of which compensate the disadvantages of step a) and whose occasionally occurring problems of step c) are solved) and
• the surface treatment preferred in accordance with the invention in step c) (which benefits from step a), solves any problems of step b) which occur, and does not destroy the advantages of step b)).

The corresponding methods of surface treatment are known in principle to the person skilled in the art.

• wobei durch dieses Behandeln die Oberflächenhärte des in Schritt b) hergestellten oder bereitgestellten Rohlings um nicht mehr als 10 % erhöht wird und/oder
• wobei der Rohling nach Schritt c) an der Oberfläche einen arithmetischen Mittenrauwert R_a aufweist, der kleiner ist als 0,8 µm, bevorzugt kleiner ist als 0,4 µm, besonders bevorzugt kleiner ist als 0,1 µm und/oder
• wobei die Oberfläche des Rohlings nach Schritt c) frei von Anlaufschichten und/oder Zunderschichten ist und/oder
• wobei die Oberfläche des Rohlings nach Schritt c) einen Glanzwert von mindestens 75 GE, bevorzugt von mindestens 125 GE, besonders bevorzugt von mindestens 250 GE, ganz besonders bevorzugt von mindestens 350 GE und speziell bevorzugt von mindestens 450 GE aufweist, gemessen über eine Messung des gerichteten Reflexionsgrades bei 20° gemäß DIN EN ISO 7668: 2011-03 .

Preferred is a process according to the invention (preferably as referred to above as preferred), comprising after step b) the step to ensure the quality and / or to facilitate the visual inspection of the quality of the surface of the blank
c) treating the surface of the blank with one or more methods selected from the group consisting of electropolishing and plasma polishing;

• wherein by this treatment the surface hardness of the blank produced or provided in step b) is increased by not more than 10% and / or
• wherein the blank after step c) on the surface an arithmetic mean roughness R _a which is smaller than 0.8 μm, preferably smaller than 0.4 μm, particularly preferably smaller than 0.1 μm and / or
• wherein the surface of the blank after step c) is free from tarnish layers and / or scale layers and / or
• wherein the surface of the blank after step c) has a gloss value of at least 75 GE, preferably of at least 125 GE, more preferably of at least 250 GE, most preferably of at least 350 GE and especially preferably of at least 450 GE, measured via a measurement of directed reflectance at 20 ° according to DIN EN ISO 7668: 2011-03 ,

The unit GE stands for gloss units.

Correspondingly preferred methods are particularly advantageous, wherein in principle the reasons already explained above apply. In our own experiments, however, it has surprisingly been found that treating the surface of the blank with one or more methods selected from the group consisting of electropolishing and plasma polishing at particularly low cost and with a particularly high process reliability leads to particularly good results. It was quite surprising that electropolishing and plasma polishing in the present case surpassed so much the other methods of surface treatment in terms of performance. The particularly high suitability of these processes for the oxide and / or tarnish layers occasionally formed in step b) of the process according to the invention was unpredictable and thus completely surprising. Using these methods, surprisingly, the features defined above can be realized in the blanks produced. This is particularly advantageous for reasons of machinability of the producible blanks and in view of the possibility of reliable quality assurance.

Of the two methods, plasma polishing is preferred both for reasons of particularly high safety at work and in terms of the result to be achieved.

• durch Plasmapolieren des Rohlings erfolgt, wobei ein, mehrere oder sämtliche der folgenden Parameter eingestellt werden:
  • Spannung: 270 bis 400 V DC, vorzugsweise 280 bis 360 V DC,
  • Stromdichte: 0,1 bis 1 A/cm², vorzugsweise 0,15 bis 0,5A/cm²,
  • Bearbeitungszeit: 1 bis 10 min; vorzugsweise 1,5 bis 5 min,
  • Elektrolyttemperatur: 50 bis 98 °C, vorzugsweise 65 bis 90 °C,
  • Elektrolyt: wässrige Elektrolytlösung mit einer Elektrolytkonzentration von 2 bis 12 Gew.%, wobei der Elektrolyt vorzugsweise ein Ammoniumsalz ist,
  • pH-Wert: 1 bis 7, vorzugsweise 4,5 bis 6,5
  oder
• durch Elektropolieren des Rohlings erfolgt, wobei ein, mehrere oder sämtliche der folgenden Parameter eingestellt werden:
  • Spannung: 2 bis 60 V DC, vorzugsweise 5 bis 40 V DC, besonders bevorzugt 7 bis 20 V DC,
  • Stromdichte: 0,05 bis 3 A/cm², bevorzugt 0,075 bis 0,5 A/cm²,
  • Elektrolyttemperatur: 20 bis 80 °C, bevorzugt 40 bis 70 °C,
  • Elektrolyt: 90 Gew.% Glycerin mit 10 Gew.% Schwefelsäure,
  • Bearbeitungsdauer: 1 bis 25 min, bevorzugt 5 bis 15 min.

Preferred is a process according to the invention (preferably as preferred above), wherein the treatment of the surface of the blank in step c)

• by plasma polishing the blank, setting one, several or all of the following parameters:
  • Voltage: 270 to 400 V DC, preferably 280 to 360 V DC,
  • Current density: 0.1 to 1 A / cm ² , preferably 0.15 to 0.5 A / cm ² ,
  • Processing time: 1 to 10 min; preferably 1.5 to 5 minutes,
  • Electrolyte temperature: 50 to 98 ° C, preferably 65 to 90 ° C,
  • Electrolyte: aqueous electrolyte solution having an electrolyte concentration of 2 to 12% by weight, the electrolyte preferably being an ammonium salt,
  • pH: 1 to 7, preferably 4.5 to 6.5
  or
• by electropolishing the blank, setting one, several or all of the following parameters:
  • Voltage: 2 to 60 V DC, preferably 5 to 40 V DC, particularly preferably 7 to 20 V DC,
  • Current density: 0.05 to 3 A / cm ² , preferably 0.075 to 0.5 A / cm ² ,
  • Electrolyte temperature: 20 to 80 ° C, preferably 40 to 70 ° C,
  • Electrolyte: 90% by weight of glycerol with 10% by weight of sulfuric acid,
  • Processing time: 1 to 25 minutes, preferably 5 to 15 minutes.

Correspondingly preferred methods are particularly advantageous, wherein in principle the reasons explained above apply. Using the above parameters, the best results were obtained in own experiments on average.

• wobei die Dentallegierung vorzugsweise Cobalt in einer Menge von 35 Gew.% bis 70 Gew.%, bevorzugt in einer Menge von 50 Gew.% bis 70 Gew.%, Chrom in einer Menge von 17 Gew.% bis 35 Gew.%, bevorzugt in einer Menge von 20 Gew.% bis 32 Gew.%, Wolfram in einer Menge von 0 bis 20 Gew.%, bevorzugt in einer Menge von 0 bis 12 Gew.-% und Molybdän in einer Menge von 0 Gew.% bis 15 Gew.%, bevorzugt in einer Menge von 0 Gew.% bis 10 Gew.%, ganz besonders bevorzugt in einer Menge von 3 Gew.% bis 8 Gew.% enthält, jeweils bezogen auf die Gesamtmasse der Dentallegierung, und/oder
• wobei die Wirksumme [Cr] + 3,3 (0,5 * [W] + [Mo]) > 40 ist, bevorzugt > 45 ist.

Preferred is a method of the invention (preferably as referred to above as preferred), wherein the metallic workpiece consists of a dental alloy, wherein the dental alloy preferably comprises one or more elements selected from the group consisting of iron, gold, cobalt, chromium, copper , Molybdenum, nickel, palladium, platinum, silver, titanium, tungsten, tin, zinc, rhenium, indium, gallium, tantalum and rhodium, the dental alloy particularly preferably being a cobalt-chromium alloy,

• wherein the dental alloy preferably cobalt in an amount of 35 wt.% To 70 wt.%, Preferably in an amount of 50 wt.% To 70 wt.%, Chromium in an amount of 17 wt.% To 35 wt.%, Preferably in an amount of 20 Wt.% To 32 wt.%, Tungsten in an amount of 0 to 20 wt.%, Preferably in an amount of 0 to 12 wt.%, And molybdenum in an amount of 0 wt.% To 15 wt.%, Preferably in an amount of 0% by weight to 10% by weight, very particularly preferably in an amount of 3% by weight to 8% by weight, in each case based on the total mass of the dental alloy, and / or
• where the effective sum is [Cr] + 3.3 (0.5 * [W] + [Mo])> 40, preferably> 45.

Correspondingly preferred methods are particularly advantageous since, due to their material properties, corresponding metallic workpieces are particularly strongly influenced by the machining of at least regions of the workpiece surface. The influence of the machining is therefore often particularly disadvantageous in the preferred method; the absolute improvement to be achieved by the heat treatment provided according to the invention is, however, advantageously particularly pronounced.

The above statements should be understood to mean that all metallic components are attributed to the dental alloy. However, a corresponding workpiece may contain small amounts of non-metallic constituents such as impurities or intentionally introduced components, the content of non-metallic constituents being preferably less than 10% by volume, preferably less than 5% by volume, based on the total volume of the workpiece. The non-metallic constituents are not to be understood as part of the dental alloy.

The definition of the effective sum can be found in DIN 13912: 1996, where in the present case it has been shown that the sum of the effect should advantageously be greater (> 40) than required in DIN 13912: 1996.

The term dental alloy is a generic term for all alloys that are suitable for dentures in the dental field.

• wobei bevorzugt im Zugversuch der Bruch der Dentallegierung dann erfolgt, wenn im Last/Dehnungs-Diagramm die maximale Last gemessen wird, gemessen nach ISO 22674-2016.

A method according to the invention (preferably as described above as preferred) is preferred, wherein the metallic workpiece consists of a dental alloy whose hardness increases with plastic deformation,

• wherein preferably in the tensile test, the fracture of the dental alloy takes place when the maximum load is measured in the load / elongation diagram, measured according to ISO 22674-2016.

Correspondingly preferred methods are therefore also particularly advantageous since corresponding metallic workpieces consisting of dental alloys whose hardness increases during plastic deformation can, due to their material properties, be particularly strongly influenced by the machining of at least areas of the workpiece surface. The above statements apply mutatis mutandis.

In the load / elongation diagram recorded according to ISO 22674-2016, a load higher than the load at the time of break (maximum load) is measured for no strain before breakage. For example, this is in contrast to materials where it does not break until further strain is taken from the point of maximum load (with the measured load falling to break).

A process according to the invention is preferred (preferably as described above as preferred), wherein step b) is carried out in such a way that
the blank produced in step b) and / or the blank produced in step c) has at least partially an austenitic structure,
wherein the austenitic phase is preferably present in an amount of at least 50% by volume, more preferably at least 66% by volume, most preferably 90% by volume, based on the total volume of the blank
and or
in step b) an austenitic phase is generated or the proportion of an austenitic phase is increased.
Corresponding methods are particularly advantageous because a further advantageous technical effect is achieved in a synergistic manner with the heat treatment (in particular during solution heat treatment) according to step b). By heat treatment, in preferred processes, an austenitic phase is produced in the blank or the proportion of an austenitic phase already present (after step a) is increased. The presence of a corresponding structural constituent has an advantageous effect on the mechanical properties of the blank.

The austenitic phase fraction is determined using image analysis according to the standard ASTM E1245-03 (2016) "Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis".

• d) Formen des Bauteils mittels eines subtraktiven CAD/CAM-Verfahrens aus dem in Schritt b) oder Schritt c) oder einem Folgeschritt hergestellten Rohling,
  • vorzugsweise unter Verwendung eines Schruppfräsers, bevorzugt eines Torusfräsers, besonders bevorzugt eines 3 mm Torusfräsers.

A method according to the invention (preferably as described above as preferred) is preferred for producing a dental component, preferably a dental prosthesis part or dental auxiliary part, with the following additional step:

• d) forming the component by means of a subtractive CAD / CAM method from the blank produced in step b) or step c) or a subsequent step,
  • preferably using a roughing cutter, preferably a torus milling cutter, particularly preferably a 3 mm torus milling cutter.

Correspondingly preferred methods are particularly advantageous in that they produce dental components of high quality while at the same time advantageously reducing the wear of the tool used, i. the service life of the tool is increased.

Roughing cutters are known to the person skilled in the art; These are cutters that enable good chip removal. They can be recognized regularly by an interrupted profile of the tool cutting edge.

The advantageous technical effect is particularly pronounced if the forming of the component takes place by means of a subtractive CAD / CAM method using a torus milling cutter or another roughing cutter (torus milling cutters are, for example, in US Pat DE 10 2005 043 842 A1 illustrated). This is due to the fact that often a torus cutter or other roughing cutter is used for the initial processing of the surface of a blank, which is thus particularly affected by the adverse hardening of the blank by the machining in step a).

• eine definierte Schneide aufweist und/oder
• aus Vollhartmetall besteht und/oder
• mit einer Beschichtung beschichtet ist, wobei die Beschichtung bevorzugt mittels eines PVD-Verfahrens aufgebracht wurde,
  • wobei die Beschichtung vorzugsweise eine Verbindung ausgewählt aus der Gruppe bestehend aus TiN, TiAlN und AlCrN umfasst oder
  • wobei die Beschichtung CBN-Feinkorn in einer metallischen Binderphase umfasst.

In preferred methods, a torus milling cutter or another roughing cutter is preferably used which has already been optimized even for low wear in order to achieve a particularly high durability of the tool. In the light of these considerations, a method according to the invention is preferred (preferably as described above as preferred),
wherein in step d) a roughing cutter is used, preferably a Torusfräser, wherein the roughing cutter

• has a defined cutting edge and / or
• made of solid carbide and / or
• coated with a coating, the coating preferably being applied by means of a PVD process,
  • wherein the coating preferably comprises a compound selected from the group consisting of TiN, TiAlN and AlCrN or
  • wherein the coating comprises CBN fine grain in a metallic binder phase.

The advantages according to the preferred method of the invention are particularly evident when further finishing is carried out following the use of a torus cutter or other roughing cutter. In practice, for example, the CAD / CAM milling of dental components often takes place in at least two partial steps. In a first part-step, so-called roughing takes place. This step is about removing a large volume of material as effectively and quickly as possible. In this case, a contour is traversed, which represents an allowance for the final contour. Preferably, a torus cutter having a diameter in the range of 2.5 to 5 mm, particularly preferably 3 mm, is used here. In the subsequent part step, the so-called finishing takes place. Here, the final contour is traversed with a finer cutter. The diameter of this cutter is preferably in the range of 1.5 to 2.5 mm, more preferably 2 mm. Preferably, a burr radius cutter is used in sizing. These two milling steps can be followed by further partial steps with finer milling, in which case in particular the finer structures and radii are worked out, for which the milling cutter was still too large during sizing. Preferably, for this purpose, a Stirnradiusfräser be used with a diameter in the range of 0.5 to 1.5 mm, particularly preferably in the range of 0.8 to 1.2 mm.

In the light of these considerations, a method according to the invention is preferred (preferably as described above as preferred),
wherein in step d) the component is formed by means of a subtractive CAD / CAM process in two or more steps, wherein in the first step a roughing cutter, preferably a torus cutter, is used and wherein in the second step or in one or more of the further Steps a finishing mill, preferably a Stirnradiusfräser, is used, which is finer than the roughing cutter.

A variety of the objects described above are achieved by a metallic blank for the production of dental components by means of a subtractive CAD / CAM method,
wherein the blank has a quotient surface hardness to core hardness which is smaller than 1.2 and at the surface has an arithmetic mean roughness R _a , which is smaller than 0.8 microns
and or
wherein the blank can be produced by a method according to the invention.

The advantages of blanks according to the invention emerge directly from the above statements on inventive and preferred methods according to the invention. The above statements apply mutatis mutandis.

Preferably, the blank has a (mean) surface hardness of from 200 HV10 to 400 HV10, preferably from 250 to 350 HV10, more preferably from 260 HV10 to 300 HV10.

• wobei die austenitische Phase bevorzugt in einer Menge von zumindest 50 Vol.%, besonders bevorzugt zumindest 66 Vol.%, ganz besonders bevorzugt 90 Vol.%, vorliegt, bezogen auf das Gesamtvolumen des Rohlings,

und/oder
wobei die mittlere Korngröße des Rohlings im Bereich von 10 µm bis 500 µm, bevorzugt im Bereich von 20 µm bis 200 µm, besonders bevorzugt im Bereich von 50 µm bis 100 µm, liegt
und/oder
wobei der Rohling eine maximale Porengröße aufweist, die kleiner ist als 100 µm, bevorzugt kleiner ist als 10 µm, besonders bevorzugt kleiner ist als 1 µm
und/oder
wobei der Rohling eine Porosität aufweist, die kleiner ist als 5 %, bevorzugt kleiner ist als 1 %, besonders bevorzugt kleiner ist als 0,1 %, bezogen auf das Gesamtvolumen des Rohlings
und/oder
wobei im Rohling der Gesamtvolumenanteil von Ausscheidungen, die aus intermetallischen Verbindungen, Carbiden oder Nitriden bestehen, kleiner ist als 10 Vol.-%, bevorzugt 2,5 Vol.-% besonders bevorzugt 1 Vol.-%, bezogen auf das Gesamtvolumen des Rohlings (die Bestimmung des Gesamtvolumenanteils der Ausscheidungen erfolgt dabei vorzugsweise mittels Bildanalyse gemäß der Norm ASTM E1245-03(2016) „Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis“)
und/oder
wobei der Rohling aus einer Dentallegierung besteht, wobei die Dentallegierung bevorzugt ein oder mehrere Elemente umfasst, die ausgewählt sind aus der Gruppe bestehend aus Eisen, Gold, Cobalt, Chrom, Kupfer, Molybdän, Nickel, Palladium, Platin, Silber, Titan, Wolfram, Zinn, Zink, Rhenium, Indium, Gallium, Tantal und Rhodium, wobei die Dentallegierung besonders bevorzugt eine Cobalt-Chrom-Legierung ist,

• wobei die Dentallegierung vorzugsweise Cobalt in einer Menge von 35 Gew.% bis 70 Gew.%, bevorzugt in einer Menge von 50 Gew.% bis 70 Gew.%, Chrom in einer Menge von 17 Gew.% bis 35 Gew.%, bevorzugt in einer Menge von 20 Gew.% bis 32 Gew.%, Wolfram in einer Menge von 0 bis 20 Gew.%, bevorzugt in einer Menge von 0 bis 12 Gew.-% und Molybdän in einer Menge von 0 Gew.% bis 15 Gew.%, bevorzugt in einer Menge von 0 Gew.% bis 10 Gew.%, ganz besonders bevorzugt in einer Menge von 3 Gew.% bis 8 Gew.% enthält, jeweils bezogen auf die Gesamtmasse der Dentallegierung, und/oder
• wobei die Wirksumme [Cr] + 3,3 (0,5 * [W] + [Mo]) > 40 ist, bevorzugt > 45 ist und/oder

wobei der Rohling aus einer Dentallegierung besteht, deren Härte bei plastischer Verformung steigt,

• wobei bevorzugt im Zugversuch der Bruch der Dentallegierung dann erfolgt, wenn im Last/Dehnungs-Diagramm die maximale Last gemessen wird, gemessen nach ISO 22674-2016

und/oder
wobei der Rohling die folgenden Abmessungen aufweist:

• Kreisdurchmesser eines runden Rohlings oder Kantenlänge eines rechteckigen Rohlings: 15 bis 250 mm, bevorzugt 75 bis 150 mm und
• Höhe: 5 bis 30 mm; bevorzugt 7,5 bis 25 mm.

Preferred is a blank according to the invention,
wherein the blank has a quotient surface hardness to core hardness which is less than 1.1, preferably less than 1.05
and or
wherein the blank has on the surface an arithmetic mean roughness R _a which is less than 0.4 μm, preferably less than 0.1 μm
and or
wherein the surface of the blank is free from tarnish layers and / or scale layers
and or
wherein the surface of the blank after step c) has a gloss value of at least 75 GE, preferably of at least 125 GE, more preferably of at least 250 GE, most preferably of at least 350 GE and especially preferably of at least 450 GE, measured via a measurement of directed reflectance at 20 ° accordingly DIN EN ISO 7668: 2011-03
and or
wherein the blank at least partially has an austenitic structure,

• wherein the austenitic phase is preferably present in an amount of at least 50% by volume, more preferably at least 66% by volume, most preferably 90% by volume, based on the total volume of the blank,

and or
wherein the mean grain size of the blank in the range of 10 microns to 500 microns, preferably in the range of 20 microns to 200 microns, more preferably in the range of 50 microns to 100 microns, is
and or
wherein the blank has a maximum pore size which is less than 100 microns, preferably less than 10 microns, more preferably less than 1 micron
and or
wherein the blank has a porosity which is less than 5%, preferably less than 1%, more preferably less than 0.1%, based on the total volume of the blank
and or
wherein in the blank the total volume fraction of precipitates consisting of intermetallic compounds, carbides or nitrides is less than 10% by volume, preferably 2.5% by volume, more preferably 1% by volume, based on the total volume of the blank ( The determination of the total volume fraction of precipitates is preferably carried out by means of image analysis according to the standard ASTM E1245-03 (2016) "Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis").
and or
wherein the blank is made of a dental alloy, wherein the dental alloy preferably comprises one or more elements selected from the group consisting of iron, gold, cobalt, chromium, copper, molybdenum, nickel, palladium, platinum, silver, titanium, tungsten, Tin, zinc, rhenium, indium, gallium, tantalum and rhodium, the dental alloy particularly preferably being a cobalt-chromium alloy,

• wherein the dental alloy preferably cobalt in an amount of 35 wt.% To 70 wt.%, Preferably in an amount of 50 wt.% To 70 wt.%, Chromium in an amount of 17 wt.% To 35 wt.%, Preferably in an amount of 20% by weight to 32% by weight, tungsten in an amount of 0 to 20% by weight, preferably in an amount of 0 to 12% by weight and molybdenum in an amount of 0% by weight to 15 % By weight, preferably in an amount of from 0% by weight to 10% by weight, very particularly preferably in an amount of from 3% by weight to 8% by weight, based in each case on the total mass of the dental alloy, and / or
• wherein the sum of effective [Cr] + 3.3 (0.5 * [W] + [Mo])> 40, preferably> 45 and / or

wherein the blank consists of a dental alloy whose hardness increases with plastic deformation,

• wherein preferably in the tensile test, the fracture of the dental alloy takes place when the maximum load is measured in the load / elongation diagram, measured according to ISO 22674-2016

and or
the blank having the following dimensions:

• Circle diameter of a round blank or edge length of a rectangular blank: 15 to 250 mm, preferably 75 to 150 mm and
• Height: 5 to 30 mm; preferably 7.5 to 25 mm.

The advantages of blanks according to the invention in most cases arise directly from the above statements on inventive and preferred methods according to the invention. The above statements apply mutatis mutandis.

Blanks comprising microstructural constituents having the above-indicated particle size and blanks which have a specific maximum pore size and / or porosity specified above are preferred because they have particularly high chemical resistance and also have particularly favorable mechanical properties and are particularly advantageous high quality and durable dental components can be processed.

Porosity and pore size are determined by image analysis according to standard ASTM E1245-03 (2016) "Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis".

The mean grain size is determined by means of image analysis according to the standard ASTM E1382-97 (2015) "Standard Test Methods for Determining Average Grain Size Using Semiautomatic and Automatic Image Analysis".

Blanks of the dimensions given above are preferred because they are compatible with the conventional CAD / CAM machine tools and can also store and send particularly favorable.

• ein oder mehrere erfindungsgemäße Rohlinge und
• ein oder mehrere Schruppfräser, bevorzugt Torusfräser.

Taking into account the above remarks on the advantages of blanks according to the invention, in particular in subtractive CAD / CAM processes in which a torus milling cutter is used for processing the near-surface layers of the blank, it will be apparent to those skilled in the art that a plurality of the above-described objects is achieved by a Kit for manufacturing dental components using CAD / CAM milling method

• one or more blanks of the invention and
• one or more roughing cutters, preferably torus cutters.

The advantages of corresponding kits according to the invention arise directly from the advantages of corresponding blanks according to the invention and corresponding methods according to the invention for producing a dental component using a torus milling cutter. The above statements apply mutatis mutandis.

• wobei die Beschichtung vorzugsweise eine Verbindung ausgewählt aus der Gruppe bestehend aus TiN, TiAlN und AlCrN umfasst oder
• wobei die Beschichtung CBN-Feinkorn in einer metallischen Binderphase umfasst.

Preferred is a kit according to the invention (preferably as referred to above as preferred), wherein the one or more roughing cutters
Torusfräser are
and or
have a defined cutting edge
and or
made of solid carbide
and or
coated with a coating, the coating preferably being applied by means of a PVD process,

• wherein the coating preferably comprises a compound selected from the group consisting of TiN, TiAlN and AlCrN or
• wherein the coating comprises CBN fine grain in a metallic binder phase.

Correspondingly preferred kits according to the invention are advantageous since they comprise specific torus cutters which have already been optimized even for low wear, whereby a particularly high durability of the tool can be achieved in combination with blanks according to the invention. The above-mentioned torus cutters are also preferred for use in a method according to the invention for producing a dental component, see above.

A multiplicity of the objects described above are also achieved by the use of a blank according to the invention, in the manufacture of dental components by means of subtractive CAD / CAM methods, for increasing the service life of the tool used in the subtractive CAD / CAM method, preferably a roughing cutter, particularly preferably einesTorusfräsers.

The advantages of corresponding uses according to the invention emerge directly from the above statements on inventive and preferred processes and blanks according to the invention. The above statements apply mutatis mutandis.

• wobei das Spannungsarmglühen vorzugsweise bei einer Temperatur im Bereich von 50 bis 70 % der in °C angegebenen Solidustemperatur erfolgt und wobei das Lösungsglühen vorzugsweise bei einer Temperatur oberhalb der Phasenumwandlungstemperatur der Umwandlung von der hexagonalen Packung zur kubischen Packung und bei einer Temperatur unterhalb der Solidustemperatur erfolgt,
  • wobei die Phasenumwandlungstemperatur die Temperatur ist, bei der es zur Phasenumwandlung der Primärphase des Rohlings kommt, und die Solidustemperatur die Temperatur ist, bei der es zum Aufschmelzen der Phase mit dem niedrigsten Schmelzpunkt im Rohling kommt,

wobei die Wärmebehandlung des Rohlings bei einem Druck von weniger als 5 MPa erfolgt.A variety of the objects described above are also achieved by the use of a heat treatment in the manufacture of a high machinability blank for the manufacture of dental components by subtractive CAD / CAM techniques.
wherein the surface hardness of the blank prior to the heat treatment is higher than its core hardness,
wherein the heat treatment of the blank by stress relief annealing or solution annealing, preferably solution annealing occurs,

• wherein stress relief annealing is preferably carried out at a temperature in the range of 50 to 70% of the solidus temperature indicated in ° C, and wherein the solution heat treatment is preferably at a temperature above the phase transition temperature of the hexagonal packing to cubic packing conversion and at a temperature below the solidus temperature;
  • wherein the phase transition temperature is the temperature at which phase transition of the primary phase of the blank occurs, and the solidus temperature is the temperature at which melting of the lowest melting point phase in the blank occurs,

wherein the heat treatment of the blank is carried out at a pressure of less than 5 MPa.

The advantages of corresponding uses according to the invention emerge directly from the above statements on inventive and preferred processes according to the invention. The above statements apply mutatis mutandis.

• wobei die Phasenumwandlungstemperatur die Temperatur ist, bei der es zur Phasenumwandlung der Primärphase des Rohlings kommt, und die Solidustemperatur die Temperatur ist, bei der es zum Aufschmelzen der Phase mit dem niedrigsten Schmelzpunkt im Rohling kommt

und/oder
wobei die Wärmebehandlung bei einer Temperatur im Bereich von 950 °C bis 1300 °C, besonders bevorzugt im Bereich von 1000 °C bis 1250 °C, erfolgt
und/oder
wobei die Wärmebehandlung des Rohlings bei einem Druck von weniger als 0,5 MPa erfolgt
und/oder
wobei die Wärmebehandlung des Rohlings, vorzugsweise die Wärmebehandlung des Rohlings bei der maximalen Behandlungstemperatur, für eine Dauer im Bereich von 15 bis 240 Minuten, bevorzugt im Bereich von 30 bis 180 Minuten, besonders bevorzugt im Bereich von 45 bis 120 Minuten, erfolgt
und/oder
wobei nach der Wärmebehandlung des Rohlings ein Abkühlen des Rohlings innerhalb von weniger als 20 Minuten, bevorzugt innerhalb von weniger als 10 Minuten, besonders bevorzugt innerhalb von weniger als 5 min, auf eine Temperatur erfolgt, die, gemessen im Massenschwerpunkt des Rohlings, unter 50% der in °C angegebenen Solidustemperatur liegt, bei einem Rohling mit den Hauptbestandteilen Cobalt und Chrom bevorzugt bei unter 700 °C liegt,
und/oder
wobei die Wärmebehandlung und/oder ein Abkühlen des Rohlings in einem Inertgasstrom oder im Vakuum erfolgt,

• wobei vorzugsweise das Inertgas ausgewählt ist aus der Gruppe bestehend aus Stickstoff, Helium, Argon und deren Mischungen.

A use according to the invention is preferred (preferably as described above as preferred),
wherein in stress relief annealing the temperature is selected so that there is no phase separation in the blank, and wherein the solution annealing at a temperature greater than 50 ° C above, preferably more than 100 ° C above, the phase transition temperature of the hexagonal Packing for cubic packing and at a temperature of more than 100 ° C. below, preferably by more than 150 ° C. below, particularly preferably by more than 200 ° C., below the solidus temperature,

• wherein the phase transition temperature is the temperature at which phase transition of the primary phase of the blank occurs, and the solidus temperature is the temperature at which melting of the lowest melting point phase in the blank occurs

and or
wherein the heat treatment at a temperature in the range of 950 ° C to 1300 ° C, more preferably in the range of 1000 ° C to 1250 ° C, takes place
and or
wherein the blank is heat treated at a pressure of less than 0.5 MPa
and or
wherein the heat treatment of the blank, preferably the heat treatment of the blank at the maximum treatment temperature, for a duration in the range of 15 to 240 minutes, preferably in the range of 30 to 180 minutes, more preferably in the range of 45 to 120 minutes
and or
wherein, after the blank has been heat-treated, the blank is cooled to less than 20 minutes, preferably less than 10 minutes, more preferably less than 5 minutes, to a temperature below 50% as measured at the center of gravity of the blank the solidus temperature given in ° C, in a blank with the main components cobalt and chromium is preferably below 700 ° C,
and or
wherein the heat treatment and / or cooling of the blank takes place in an inert gas stream or in a vacuum,

• wherein preferably the inert gas is selected from the group consisting of nitrogen, helium, argon and mixtures thereof.

The advantages of corresponding preferred uses according to the invention are directly apparent from the above statements on inventive and preferred processes according to the invention. The above statements apply mutatis mutandis.

• wobei der Rohling vor dem elektrochemischen Verfahren einen Quotienten Oberflächenhärte zu Kernhärte aufweist, der kleiner ist als 1,2 und
• wobei durch das elektrochemische Verfahren die Oberflächenhärte des Rohlings um nicht mehr als 10 % erhöht wird.

A multiplicity of the objects described above are also achieved by the use of an electrochemical method during the cleaning, preferably the cleaning removing oxidic materials, and / or smoothing of a blank for the production of dental components by means of subtractive CAD / CAM methods,

• wherein the blank before the electrochemical process has a quotient surface hardness to core hardness, which is less than 1.2 and
• wherein the surface hardness of the blank is increased by not more than 10% by the electrochemical method.

The advantages of corresponding uses according to the invention emerge directly from the above statements on inventive and preferred processes and blanks according to the invention. The above statements apply mutatis mutandis.

• wobei beim Plasmapolieren vorzugsweise ein, mehrere oder sämtliche der folgenden Parameter eingestellt werden:
  • Spannung: 270 bis 400 V DC, vorzugsweise 280 bis 360 V DC,
  • Stromdichte: 0,1 bis 1 A/cm², vorzugsweise 0,15 bis 0,5A/cm²,
  • Bearbeitungszeit: 1 bis 10 min; vorzugsweise 1,5 bis 5 min,
  • Elektrolyttemperatur: 50 bis 98 °C, vorzugsweise 65 bis 90 °C,
  • Elektrolyt: wässrige Elektrolytlösung mit einer Elektrolytkonzentration von 2 bis 12 Gew.%, wobei der Elektrolyt vorzugsweise ein Ammoniumsalz ist,
  • pH-Wert: 1 bis 7, vorzugsweise 4,5 bis 6,5
  und
• wobei beim Elektropolieren vorzugsweise ein, mehrere oder sämtliche der folgenden Parameter eingestellt werden:
  • Spannung: 2 bis 60 V DC, vorzugsweise 5 bis 40 V DC, besonders bevorzugt 7 bis 20 V DC,
  • Stromdichte: 0,05 bis 3 A/cm², bevorzugt 0,075 bis 0,5 A/cm²,
  • Elektrolyttemperatur: 20 bis 80 °C, bevorzugt 40 bis 70 °C,
  • Elektrolyt: 90 Gew.% Glycerin mit 10 Gew.% Schwefelsäure,
  • Bearbeitungsdauer: 1 bis 25 min, bevorzugt 5 bis 15 min

und/oder
wobei der Rohling nach dem elektrochemischen Verfahren an der Oberfläche einen arithmetischen Mittenrauwert R_a aufweist, der kleiner ist als 0,8 µm, bevorzugt kleiner ist als 0,4 µm, besonders bevorzugt kleiner ist als 0,1 µm
und/oder
wobei die Oberfläche des Rohlings nach dem elektrochemischen Verfahren frei von Anlaufschichten und/oder Zunderschichten ist
und/oder
wobei die Oberfläche des Rohlings nach Schritt c) einen Glanzwert von mindestens 75 GE, bevorzugt von mindestens 125 GE, besonders bevorzugt von mindestens 250 GE, ganz besonders bevorzugt von mindestens 350 GE und speziell bevorzugt von mindestens 450 GE aufweist, gemessen über eine Messung des gerichteten Reflexionsgrades bei 20° entsprechend DIN EN ISO 7668: 2011-03 .A use according to the invention is preferred (preferably as described above as preferred),
wherein the electrochemical process is selected from the group consisting of electropolishing and plasma polishing, preferably plasma polishing,

• wherein in plasma polishing preferably one, several or all of the following parameters are set:
  • Voltage: 270 to 400 V DC, preferably 280 to 360 V DC,
  • Current density: 0.1 to 1 A / cm ² , preferably 0.15 to 0.5 A / cm ² ,
  • Processing time: 1 to 10 min; preferably 1.5 to 5 minutes,
  • Electrolyte temperature: 50 to 98 ° C, preferably 65 to 90 ° C,
  • Electrolyte: aqueous electrolyte solution having an electrolyte concentration of 2 to 12% by weight, the electrolyte preferably being an ammonium salt,
  • pH: 1 to 7, preferably 4.5 to 6.5
  and
• wherein during electropolishing preferably one, several or all of the following parameters are set:
  • Voltage: 2 to 60 V DC, preferably 5 to 40 V DC, particularly preferably 7 to 20 V DC,
  • Current density: 0.05 to 3 A / cm ² , preferably 0.075 to 0.5 A / cm ² ,
  • Electrolyte temperature: 20 to 80 ° C, preferably 40 to 70 ° C,
  • Electrolyte: 90% by weight of glycerol with 10% by weight of sulfuric acid,
  • Processing time: 1 to 25 minutes, preferably 5 to 15 minutes

and or
wherein the blank according to the electrochemical method on the surface has an arithmetic mean roughness R _a , which is smaller than 0.8 microns, preferably less than 0.4 microns, more preferably less than 0.1 microns
and or
wherein the surface of the blank after the electrochemical process is free of tarnish layers and / or scale layers
and or
wherein the surface of the blank after step c) has a gloss value of at least 75 GE, preferably of at least 125 GE, more preferably of at least 250 GE, most preferably of at least 350 GE and especially preferably of at least 450 GE, measured via a measurement of directed reflectance at 20 ° accordingly DIN EN ISO 7668: 2011-03 ,

The advantages of corresponding preferred uses according to the invention emerge directly from the above statements on inventive and preferred processes and blanks according to the invention. The above statements apply mutatis mutandis.

• 1. Verfahren zur Herstellung eines Rohlings für die Herstellung dentaler Bauteile mittels subtraktiver CAD/CAM-Verfahren oder zur Herstellung eines dentalen Bauteils aus einem solchen Rohling, umfassend die Schritte:
  1. a) Herstellen eines Rohlings aus einem metallischen Werkstück durch zerspanende Bearbeitung von zumindest Bereichen der Werkstückoberfläche oder Bereitstellen eines solchen Rohlings, wobei die Oberflächenhärte des hergestellten oder bereitgestellten Rohlings höher ist als seine Kernhärte und die zerspanende Bearbeitung ausgewählt ist aus der Gruppe bestehend aus Drehen, Schleifen und Fräsen,
  2. b) Wärmebehandeln des in Schritt a) hergestellten oder bereitgestellten Rohlings, so dass zumindest die Oberflächenhärte des hergestellten oder bereitgestellten Rohlings reduziert wird.
• 2. Verfahren nach Aspekt 1, wobei in Schritt b) der Quotient aus Oberflächenhärte zu Kernhärte reduziert wird, wobei der Rohling nach Schritt b) bevorzugt einen Quotienten Oberflächenhärte zu Kernhärte aufweist, der kleiner ist als 1,2; bevorzugt kleiner ist als 1,1; besonders bevorzugt kleiner ist als 1,05.
• 3. Verfahren nach einem der vorangehenden Aspekte, wobei in Schritt b) das Wärmebehandeln durch Spannungsarmglühen oder Lösungsglühen, bevorzugt durch Lösungsglühen, erfolgt,
  • wobei das Spannungsarmglühen vorzugsweise bei einer Temperatur im Bereich von 50 bis 70 % der in °C angegebenen Solidustemperatur erfolgt, wobei die Temperatur vorzugsweise so gewählt wird, dass es im Rohling nicht zu einer Phasentrennung kommt und
  • wobei das Lösungsglühen vorzugsweise bei einer Temperatur oberhalb, bevorzugt um mehr als 50 °C oberhalb, besonders bevorzugt um mehr als 100 °C oberhalb, der Phasenumwandlungstemperatur der Umwandlung von der hexagonalen Packung zur kubischen Packung und bei einer Temperatur unterhalb, bevorzugt um mehr als 100 °C unterhalb, besonders bevorzugt um mehr als 150 °C unterhalb, ganz besonders bevorzugt um mehr als 200 °C unterhalb der Solidustemperatur erfolgt,
    • wobei die Phasenumwandlungstemperatur die Temperatur ist, bei der es zur Phasenumwandlung der Primärphase des Rohlings kommt, und die Solidustemperatur die Temperatur ist, bei der es zum Aufschmelzen der Phase mit dem niedrigsten Schmelzpunkt im Rohling kommt
  und/oder wobei in Schritt b) das Wärmebehandeln bei einer Temperatur im Bereich von 950 °C bis 1300 °C, bevorzugt im Bereich von 1000 °C bis 1250 °C, erfolgt und/oder wobei in Schritt b) das Wärmebehandeln bei einem Druck von weniger als 5 MPa, bevorzugt weniger als 0,5 MPa, erfolgt und/oder wobei in Schritt b) das Wärmebehandeln, vorzugsweise das Wärmebehandeln bei der maximalen Behandlungstemperatur, für eine Dauer im Bereich von 15 bis 240 Minuten, bevorzugt im Bereich von 30 bis 180 Minuten, besonders bevorzugt im Bereich von 45 bis 120 Minuten, erfolgt und/oder wobei nach Schritt b) ein Abkühlen des Rohlings innerhalb von weniger als 20 Minuten, bevorzugt innerhalb von weniger als 10 Minuten, besonders bevorzugt innerhalb von weniger als 5 min, auf eine Temperatur erfolgt, die, gemessen im Massenschwerpunkt des Rohlings, unter 50% der in °C angegebenen Solidustemperatur liegt, bei einem Rohling mit den Hauptbestandteilen Cobalt und Chrom bevorzugt bei unter 700 °C liegt, und/oder wobei in Schritt b) das Wärmebehandeln des Rohlings und/oder nach Schritt b) ein Abkühlen des Rohlings in einem Inertgasstrom oder im Vakuum erfolgt,
  • wobei vorzugsweise das Inertgas ausgewählt ist aus der Gruppe bestehend aus Stickstoff, Helium Argon und deren Mischungen.
• 4. Verfahren nach einem der vorangehenden Aspekte, wobei der Rohling nach Schritt b), vorzugsweise sowohl nach Schritt a) als auch nach Schritt b), an der Oberfläche einen arithmetischen Mittenrauwert R_a aufweist, der kleiner ist als 3,2 µm, bevorzugt kleiner als 1,6 µm.
• 5. Verfahren nach einem der vorangehenden Aspekte, wobei das in Schritt a) eingesetzte metallische Werkstück eine Scheibe ist, wobei das Verfahren zu deren Herstellung ein oder mehrere Schritte bzw. Schrittkombinationen umfasst, die ausgewählt sind aus der Gruppe bestehend aus:
  • - Gießen einer Metallschmelze zu der Scheibe oder einem Vorkörper,
  • - Heraustrennen der Scheibe aus einem Vorkörper, vorzugsweise durch ein trennendes Fertigungsverfahren ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden,
  • - Druckumformen der Scheibe oder eines Vorkörpers, vorzugsweise Schmieden oder Walzen,
  • - Formen der Scheibe durch Gießen einer Metallschmelze und Druckumformen, vorzugsweise Schmieden oder Walzen, des resultierenden Gussstücks,
  • - Formen der Scheibe durch Gießen einer Metallschmelze zu einem Vorkörper und Heraustrennen der Scheibe aus dem Vorkörper, vorzugsweise durch ein trennendes Fertigungsverfahren ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden,
  • - Formen der Scheibe durch Gießen einer Metallschmelze zu einem Vorkörper, Druckumformen des Vorkörpers, Heraustrennen der Scheibe aus dem druckumgeformten Vorkörper, wobei das Druckumformen vorzugsweise ein Schmieden oder Walzen ist, wobei das Heraustrennen vorzugsweise ein trennendes Fertigungsverfahren ist ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden,
  • - Formen der Scheibe durch Gießen einer Metallschmelze zu einem Vorkörper, Heraustrennen der Scheibe aus dem Vorkörper und Druckumformen der Scheibe, wobei das Druckumformen vorzugsweise ein Schmieden oder Walzen ist, wobei das Heraustrennen vorzugsweise ein trennendes Fertigungsverfahren ist ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden und
  • - Formen der Scheibe durch pulvermetallurgisches Erzeugen eines Vorkörpers, vorzugsweise durch heißisostatisches Pressen von Pulver, und Heraustrennen der Scheibe aus dem Vorkörper, wobei das Heraustrennen vorzugsweise ein trennendes Fertigungsverfahren ist ausgewählt aus der Gruppe bestehend aus Sägen, Drahterodieren, Laserschneiden und Wasserstrahlschneiden.
• 6. Verfahren nach einem der vorangehenden Aspekte, zusätzlich umfassend nach Schritt b) zur Sicherung der Qualität und/oder zur Erleichterung der visuellen Kontrolle der Qualität der Oberfläche des Rohlings den Schritt c) Behandeln der Oberfläche des Rohlings mit einem oder mehreren Verfahren ausgewählt aus der Gruppe bestehend aus elektrochemischen Verfahren, chemischen Verfahren, mechanischen Verfahren und deren Kombinationen, vorzugsweise elektrochemischen Verfahren,
  • wobei die elektrochemischen Verfahren vorzugsweise ausgewählt sind aus der Gruppe bestehend aus Beschichten, Elektropolieren und Plasmapolieren, besonders bevorzugt Elektropolieren und Plasmapolieren, ganz besonders bevorzugt Plasmapolieren, wobei die chemischen Verfahren vorzugsweise ausgewählt sind aus der Gruppe bestehend aus Beschichten und Beizen und wobei die mechanischen Verfahren vorzugsweise ausgewählt sind aus der Gruppe bestehend aus Beschichten, Bürsten, Polieren und Schleifen.
• 7. Verfahren nach Aspekt 6, umfassend nach Schritt b) zur Sicherung der Qualität und/oder zur Erleichterung der visuellen Kontrolle der Qualität der Oberfläche des Rohlings den Schritt
  • c) Behandeln der Oberfläche des Rohlings mit einem oder mehreren Verfahren ausgewählt aus der Gruppe bestehend aus Elektropolieren und Plasmapolieren, wobei durch dieses Behandeln die Oberflächenhärte des in Schritt b) hergestellten oder bereitgestellten Rohlings um nicht mehr als 10 % erhöht wird und/oder wobei der Rohling nach Schritt c) an der Oberfläche einen arithmetischen Mittenrauwert R_a aufweist, der kleiner ist als 0,8 µm, bevorzugt kleiner ist als 0,4 µm, besonders bevorzugt kleiner ist als 0,1 µm und/oder wobei die Oberfläche des Rohlings nach Schritt c) frei von Anlaufschichten und/oder Zunderschichten ist und/oder wobei die Oberfläche des Rohlings nach Schritt c) einen Glanzwert von mindestens 75 GE, bevorzugt von mindestens 125 GE, besonders bevorzugt von mindestens 250 GE, ganz besonders bevorzugt von mindestens 350 GE und speziell bevorzugt von mindestens 450 GE aufweist, gemessen über eine Messung des gerichteten Reflexionsgrades bei 20° gemäß DIN EN ISO 7668: 2011-03 .
• 8. Verfahren nach Aspekt 7, wobei das Behandeln der Oberfläche des Rohlings in Schritt c)
  • durch Plasmapolieren des Rohlings erfolgt, wobei ein, mehrere oder sämtliche der folgenden Parameter eingestellt werden:
    • Spannung: 270 bis 400 V DC, vorzugsweise 280 bis 360 V DC,
    • Stromdichte: 0,1 bis 1 A/cm², vorzugsweise 0,15 bis 0,5A/cm²,
    • Bearbeitungszeit: 1 bis 10 min; vorzugsweise 1,5 bis 5 min,
    • Elektrolyttemperatur: 50 bis 98 °C, vorzugsweise 65 bis 90 °C,
    • Elektrolyt: wässrige Elektrolytlösung mit einer Elektrolytkonzentration von 2 bis 12 Gew.%, wobei der Elektrolyt vorzugsweise ein Ammoniumsalz ist,
    • pH-Wert: 1 bis 7, vorzugsweise 4,5 bis 6,5
    oder durch Elektropolieren des Rohlings erfolgt, wobei ein, mehrere oder sämtliche der folgenden Parameter eingestellt werden:
    • Spannung: 2 bis 60 V DC, vorzugsweise 5 bis 40 V DC, besonders bevorzugt 7 bis 20 V DC,
    • Stromdichte: 0,05 bis 3 A/cm², bevorzugt 0,075 bis 0,5 A/cm²,
    • Elektrolyttemperatur: 20 bis 80 °C, bevorzugt 40 bis 70 °C,
    • Elektrolyt: 90 Gew.% Glycerin mit 10 Gew.% Schwefelsäure,
    • Bearbeitungsdauer: 1 bis 25 min, bevorzugt 5 bis 15 min.
• 9. Verfahren nach einem der vorangehenden Aspekte, wobei das metallische Werkstück aus einer Dentallegierung besteht, wobei die Dentallegierung bevorzugt ein oder mehrere Elemente umfasst, die ausgewählt sind aus der Gruppe bestehend aus Eisen, Gold, Cobalt, Chrom, Kupfer, Molybdän, Nickel, Palladium, Platin, Silber, Titan, Wolfram, Zinn, Zink, Rhenium, Indium, Gallium, Tantal und Rhodium, wobei die Dentallegierung besonders bevorzugt eine Cobalt-Chrom-Legierung ist, wobei die Dentallegierung vorzugsweise Cobalt in einer Menge von 35 Gew.% bis 70 Gew.%, bevorzugt in einer Menge von 50 Gew.% bis 70 Gew.%, Chrom in einer Menge von 17 Gew.% bis 35 Gew.%, bevorzugt in einer Menge von 20 Gew.% bis 32 Gew.%, Wolfram in einer Menge von 0 bis 20 Gew.%, bevorzugt in einer Menge von 0 bis 12 Gew.-% und Molybdän in einer Menge von 0 Gew.% bis 15 Gew.%, bevorzugt in einer Menge von 0 Gew.% bis 10 Gew.%, ganz besonders bevorzugt in einer Menge von 3 Gew.% bis 8 Gew.% enthält, jeweils bezogen auf die Gesamtmasse der Dentallegierung, und/oder wobei die Wirksumme [Cr] + 3,3 (0,5 * [W] + [Mo]) > 40 ist, bevorzugt > 45 ist.
• 10. Verfahren nach einem der vorangehenden Aspekte, wobei das metallische Werkstück aus einer Dentallegierung besteht, deren Härte bei plastischer Verformung steigt, wobei bevorzugt im Zugversuch der Bruch der Dentallegierung dann erfolgt, wenn im Last/Dehnungs-Diagramm die maximale Last gemessen wird, gemessen nach ISO 22674-2016.
• 11. Verfahren nach einem der vorangehenden Aspekte, wobei Schritt b) so durchgeführt wird, dass der in Schritt b) hergestellte Rohling und/oder der in Schritt c) hergestellte Rohling zumindest teilweise eine austenitische Struktur besitzt,
  • wobei die austenitische Phase bevorzugt in einer Menge von zumindest 50 Vol.%, besonders bevorzugt zumindest 66 Vol.%, ganz besonders bevorzugt 90 Vol.%, vorliegt, bezogen auf das Gesamtvolumen des Rohlings
  und/oder in Schritt b) eine austenitische Phase erzeugt oder der Anteil einer austenitischen Phase erhöht wird.
• 12. Verfahren nach einem der vorangehenden Aspekte, zur Herstellung eines dentalen Bauteils, vorzugsweise eines dentalen Prothesenteils oder dentalen Hilfsteils, mit folgendem zusätzlichen Schritt:
  • d) Formen des Bauteils mittels eines subtraktiven CAD/CAM-Verfahrens aus dem in Schritt b) oder Schritt c) oder einem Folgeschritt hergestellten Rohling,
    • vorzugsweise unter Verwendung eines Schruppfräsers, bevorzugt eines Torusfräsers, besonders bevorzugt eines 3 mm Torusfräsers.
• 12A. Verfahren nach Aspekt 12, wobei in Schritt d) ein Schruppfräser eingesetzt wird, bevorzugt ein Torusfräser, wobei der Schruppfräser
  • eine definierte Schneide aufweist und/oder
  • aus Vollhartmetall besteht und/oder
  • mit einer Beschichtung beschichtet ist, wobei die Beschichtung bevorzugt mittels eines PVD-Verfahrens aufgebracht wurde,
  • wobei die Beschichtung vorzugsweise eine Verbindung ausgewählt aus der Gruppe bestehend aus TiN, TiAlN und AlCrN umfasst oder
  • wobei die Beschichtung CBN-Feinkorn in einer metallischen Binderphase umfasst
  und/oder wobei in Schritt d) das Formen des Bauteils mittels eines subtraktiven CAD/CAM-Verfahrens in zwei oder mehr Schritten erfolgt, wobei im ersten Schritt ein Schruppfräser, bevorzugt ein Torusfräser, verwendet wird und wobei im zweiten Schritt oder in einem oder in mehreren der weiteren Schritte ein Schlichtfräser, bevorzugt ein Stirnradiusfräser, verwendet wird, der feiner ist als der Schruppfräser.
• 13. Metallischer Rohling zur Herstellung dentaler Bauteile mittels eines subtraktiven CAD/CAM-Verfahrens, wobei der Rohling einen Quotienten Oberflächenhärte zu Kernhärte aufweist, der kleiner ist als 1,2 und an der Oberfläche einen arithmetischen Mittenrauwert R_a aufweist, der kleiner ist als 0,8 µm und/oder wobei der Rohling herstellbar ist mit einem Verfahren nach einem der Aspekte 1 bis 11.
• 14. Rohling nach Aspekt 13, wobei der Rohling eine (mittlere) Oberflächenhärte von 200 HV10 bis 400 HV10, vorzugsweise von 250 bis 350 HV10, besonders bevorzugt von 260 HV10 bis 300 HV10 besitzt und/oder wobei der Rohling einen Quotienten Oberflächenhärte zu Kernhärte aufweist, der kleiner ist als 1,1, bevorzugt kleiner ist als 1,05 und/oder wobei der Rohling an der Oberfläche einen arithmetischen Mittenrauwert R_a aufweist, der kleiner ist als 0,4 µm, bevorzugt kleiner als 0,1 µm und/oder wobei die Oberfläche des Rohlings frei von Anlaufschichten und/oder Zunderschichten ist und/oder wobei die Oberfläche des Rohlings nach Schritt c) einen Glanzwert von mindestens 75 GE, bevorzugt von mindestens 125 GE, besonders bevorzugt von mindestens 250 GE, ganz besonders bevorzugt von mindestens 350 GE und speziell bevorzugt von mindestens 450 GE aufweist, gemessen über eine Messung des gerichteten Reflexionsgrades bei 20° entsprechend DIN EN ISO 7668: 2011-03 und/oder wobei der Rohling zumindest teilweise eine austenitische Struktur besitzt,
  • wobei die austenitische Phase bevorzugt in einer Menge von zumindest 50 Vol.%, besonders bevorzugt zumindest 66 Vol.%, ganz besonders bevorzugt 90 Vol.%, vorliegt, bezogen auf das Gesamtvolumen des Rohlings,
  und/oder wobei die mittlere Korngröße des Rohlings im Bereich von 10 µm bis 500 µm, bevorzugt im Bereich von 20 µm bis 200 µm, besonders bevorzugt im Bereich von 50 µm bis 100 µm, liegt und/oder wobei der Rohling eine maximale Porengröße aufweist, die kleiner ist als 100 µm, bevorzugt kleiner ist als 10 µm, besonders bevorzugt kleiner ist als 1 µm und/oder wobei der Rohling eine Porosität aufweist, die kleiner ist als 5 %, bevorzugt kleiner ist als 1 %, besonders bevorzugt kleiner ist als 0,1 %, bezogen auf das Gesamtvolumen des Rohlings und/oder wobei im Rohling der Gesamtvolumenanteil von Ausscheidungen, die aus intermetallischen Verbindungen, Carbiden oder Nitriden bestehen, kleiner ist als 10 Vol.-%, bevorzugt 2,5 Vol.-% besonders bevorzugt 1 Vol.-%, bezogen auf das Gesamtvolumen des Rohlings, und/oder wobei der Rohling aus einer Dentallegierung besteht, wobei die Dentallegierung bevorzugt ein oder mehrere Elemente umfasst, die ausgewählt sind aus der Gruppe bestehend aus Eisen, Gold, Cobalt, Chrom, Kupfer, Molybdän, Nickel, Palladium, Platin, Silber, Titan, Wolfram, Zinn, Zink, Rhenium, Indium, Gallium, Tantal und Rhodium, wobei die Dentallegierung besonders bevorzugt eine Cobalt-Chrom-Legierung ist,
  • wobei die Dentallegierung vorzugsweise Cobalt in einer Menge von 35 Gew.% bis 70 Gew.%, bevorzugt in einer Menge von 50 Gew.% bis 70 Gew.%, Chrom in einer Menge von 17 Gew.% bis 35 Gew.%, bevorzugt in einer Menge von 20 Gew.% bis 32 Gew.%, Wolfram in einer Menge von 0 bis 20 Gew.%, bevorzugt in einer Menge von 0 bis 12 Gew.-% und Molybdän in einer Menge von 0 Gew.% bis 15 Gew.%, bevorzugt in einer Menge von 0 Gew.% bis 10 Gew.%, ganz besonders bevorzugt in einer Menge von 3 Gew.% bis 8 Gew.% enthält, jeweils bezogen auf die Gesamtmasse der Dentallegierung, und/oder
  • wobei die Wirksumme [Cr] + 3,3 (0,5 * [W] + [Mo]) > 30 ist, bevorzugt > 40 ist, besonders bevorzugt > 45 ist
  und/oder wobei der Rohling aus einer Dentallegierung besteht, deren Härte bei plastischer Verformung steigt,
  • wobei bevorzugt im Zugversuch der Bruch der Dentallegierung dann erfolgt, wenn im Last/Dehnungs-Diagramm die maximale Last gemessen wird, gemessen nach ISO 22674-2016
  und/oder wobei der Rohling die folgenden Abmessungen aufweist:
  • Kreisdurchmesser eines runden Rohlings oder Kantenlänge eines rechteckigen Rohlings: 15 bis 250 mm, bevorzugt 75 bis 150 mm und
  • Höhe: 5 bis 30 mm; bevorzugt 7,5 bis 25 mm.
• 15. Kit zur Herstellung dentaler Bauteile mittels CAD/CAM Fräsverfahren umfassend ein oder mehrere Rohlinge nach einem der Aspekte 13 oder 14 und ein oder mehrere Schruppfräser.
• 15A. Kit nach Aspekt 15, wobei die ein oder mehreren Schruppfräser Torusfräser sind und/oder eine definierte Schneide aufweisen und/oder aus Vollhartmetall bestehen und/oder mit einer Beschichtung beschichtet sind, wobei die Beschichtung bevorzugt mittels eines PVD-Verfahrens aufgebracht wurde,
  • wobei die Beschichtung vorzugsweise eine Verbindung ausgewählt aus der Gruppe bestehend aus TiN, TiAlN und AlCrN umfasst oder
  • wobei die Beschichtung CBN-Feinkorn in einer metallischen Binderphase umfasst.
• 16. Verwendung eines Rohlings nach einem der Aspekte 13 oder 14, beim Herstellen von dentalen Bauteilen mittels subtraktiver CAD/CAM-Verfahren, zur Erhöhung der Standzeit des im subtraktiven CAD/CAM-Verfahren eingesetzten Werkzeuges, vorzugsweise eines Schruppfräsers, besonders bevorzugt einesTorusfräsers.
• 17. Verwendung einer Wärmebehandlung bei der Herstellung eines Rohlings mit hoher Bearbeitbarkeit für die Herstellung dentaler Bauteile mittels subtraktiver CAD/CAM-Verfahren, wobei die Oberflächenhärte des Rohlings vor der Wärmebehandlung höher ist als seine Kemhärte, wobei die Wärmebehandlung des Rohlings durch Spannungsarmglühen oder Lösungsglühen, bevorzugt Lösungsglühen, erfolgt,
  • wobei das Spannungsarmglühen vorzugsweise bei einer Temperatur im Bereich von 50 bis 70 % der in °C angegebenen Solidustemperatur erfolgt und wobei das Lösungsglühen vorzugsweise bei einer Temperatur oberhalb der Phasenumwandlungstemperatur der Umwandlung von der hexagonalen Packung zur kubischen Packung und bei einer Temperatur unterhalb der Solidustemperatur erfolgt,
    • wobei die Phasenumwandlungstemperatur die Temperatur ist, bei der es zur Phasenumwandlung der Primärphase des Rohlings kommt, und die Solidustemperatur die Temperatur ist, bei der es zum Aufschmelzen der Phase mit dem niedrigsten Schmelzpunkt im Rohling kommt,
  • wobei die Wärmebehandlung des Rohlings bei einem Druck von weniger als 5 MPa erfolgt.
• 18. Verwendung nach Aspekt 17 wobei beim Spannungsarmglühen die Temperatur so gewählt wird, dass es im Rohling nicht zu einer Phasentrennung kommt, und wobei das Lösungsglühen bei einer Temperatur um mehr als 50 °C oberhalb, bevorzugt um mehr als 100 °C oberhalb, der Phasenumwandlungstemperatur der Umwandlung von der hexagonalen Packung zur kubischen Packung und bei einer Temperatur um mehr als 100 °C unterhalb, bevorzugt um mehr als 150 °C unterhalb, besonders bevorzugt um mehr als 200 °C, unterhalb der Solidustemperatur erfolgt,
  • wobei die Phasenumwandlungstemperatur die Temperatur ist, bei der es zur Phasenumwandlung der Primärphase des Rohlings kommt, und die Solidustemperatur die Temperatur ist, bei der es zum Aufschmelzen der Phase mit dem niedrigsten Schmelzpunkt im Rohling kommt
  und/oder wobei die Wärmebehandlung bei einer Temperatur im Bereich von 950 °C bis 1300 °C, besonders bevorzugt im Bereich von 1000 °C bis 1250 °C, erfolgt und/oder wobei die Wärmebehandlung des Rohlings bei einem Druck von weniger als 0,5 MPa erfolgt und/oder wobei die Wärmebehandlung des Rohlings, vorzugsweise die Wärmebehandlung des Rohlings bei der maximalen Behandlungstemperatur, für eine Dauer im Bereich von 15 bis 240 Minuten, bevorzugt im Bereich von 30 bis 180 Minuten, besonders bevorzugt im Bereich von 45 bis 120 Minuten, erfolgt und/oder wobei nach der Wärmebehandlung des Rohlings ein Abkühlen des Rohlings innerhalb von weniger als 20 Minuten, bevorzugt innerhalb von weniger als 10 Minuten, besonders bevorzugt innerhalb von weniger als 5 min, auf eine Temperatur erfolgt, die, gemessen im Massenschwerpunkt des Rohlings, unter 50% der in °C angegebenen Solidustemperatur liegt, bei einem Rohling mit den Hauptbestandteilen Cobalt und Chrom bevorzugt bei unter 700 °C liegt, und/oder wobei die Wärmebehandlung und/oder ein Abkühlen des Rohlings in einem Inertgasstrom oder im Vakuum erfolgt,
  • wobei vorzugsweise das Inertgas ausgewählt ist aus der Gruppe bestehend aus Stickstoff, Helium, Argon und deren Mischungen.
• 19. Verwendung eines elektrochemischen Verfahrens bei der Reinigung, vorzugsweise der oxidische Materialien beseitigenden Reinigung, und/oder Glättung eines Rohlings für die Herstellung dentaler Bauteile mittels subtraktiver CAD/CAM-Verfahren, wobei der Rohling vor dem elektrochemischen Verfahren einen Quotienten Oberflächenhärte zu Kernhärte aufweist, der kleiner ist als 1,2 und wobei durch das elektrochemische Verfahren die Oberflächenhärte des Rohlings um nicht mehr als 10 % erhöht wird.
• 20. Verwendung nach Aspekt 19, wobei das elektrochemische Verfahren ausgewählt ist aus der Gruppe bestehend aus Elektropolieren und Plasmapolieren, bevorzugt Plasmapolieren,
  • wobei beim Plasmapolieren vorzugsweise ein, mehrere oder sämtliche der folgenden Parameter eingestellt werden:
    • Spannung: 270 bis 400 V DC, vorzugsweise 280 bis 360 V DC,
    • Stromdichte: 0,1 bis 1 A/cm², vorzugsweise 0,15 bis 0,5A/cm²,
    • Bearbeitungszeit: 1 bis 10 min; vorzugsweise 1,5 bis 5 min,
    • Elektrolyttemperatur: 50 bis 98 °C, vorzugsweise 65 bis 90 °C,
    • Elektrolyt: wässrige Elektrolytlösung mit einer Elektrolytkonzentration von 2 bis 12 Gew.%, wobei der Elektrolyt vorzugsweise ein Ammoniumsalz ist,
    • pH-Wert: 1 bis 7, vorzugsweise 4,5 bis 6,5
    und
  • wobei beim Elektropolieren vorzugsweise ein, mehrere oder sämtliche der folgenden Parameter eingestellt werden:
    • Spannung: 2 bis 60 V DC, vorzugsweise 5 bis 40 V DC, besonders bevorzugt 7 bis 20 V DC,
    • Stromdichte: 0,05 bis 3 A/cm², bevorzugt 0,075 bis 0,5 A/cm²,
    • Elektrolyttemperatur: 20 bis 80 °C, bevorzugt 40 bis 70 °C,
    • Elektrolyt: 90 Gew.% Glycerin mit 10 Gew.% Schwefelsäure,
    • Bearbeitungsdauer: 1 bis 25 min, bevorzugt 5 bis 15 min
    und/oder wobei der Rohling nach dem elektrochemischen Verfahren an der Oberfläche einen arithmetischen Mittenrauwert R_a aufweist, der kleiner ist als 0,8 µm, bevorzugt kleiner ist als 0,4 µm, besonders bevorzugt kleiner ist als 0,1 µm und/oder wobei die Oberfläche des Rohlings nach dem elektrochemischen Verfahren frei von Anlaufschichten und/oder Zunderschichten ist und/oder wobei die Oberfläche des Rohlings nach Schritt c) einen Glanzwert von mindestens 75 GE, bevorzugt von mindestens 125 GE, besonders bevorzugt von mindestens 250 GE, ganz besonders bevorzugt von mindestens 350 GE und speziell bevorzugt von mindestens 450 GE aufweist, gemessen über eine Messung des gerichteten Reflexionsgrades bei 20° entsprechend DIN EN ISO 7668: 2011-03 .

The following aspects and examples illustrate the present invention:

• 1. A method for producing a blank for the production of dental components by means of subtractive CAD / CAM methods or for producing a dental component from such a blank, comprising the steps:
  1. a) producing a blank from a metallic workpiece by machining at least portions of the workpiece surface or providing such a blank, wherein the surface hardness of the prepared or prepared blank is higher than its core hardness and the machining is selected from the group consisting of turning, grinding and milling,
  2. b) heat treating the blank produced or provided in step a) so as to reduce at least the surface hardness of the blank produced or provided.
• 2. The method according to aspect 1, wherein in step b) the quotient of surface hardness is reduced to core hardness, wherein the blank after step b) preferably has a quotient surface hardness to core hardness, which is less than 1.2; preferably less than 1.1; more preferably less than 1.05.
• 3. Method according to one of the preceding aspects, wherein in step b) the heat treatment is carried out by stress relief annealing or solution annealing, preferably by solution annealing,
  • wherein the stress relief annealing is preferably carried out at a temperature in the range of 50 to 70% of the solidus temperature indicated in ° C, wherein the temperature is preferably selected so that there is no phase separation in the blank, and
  • wherein solution heat treatment is preferably at a temperature above, preferably greater than 50 ° C above, more preferably greater than 100 ° C above, the phase transition temperature of the hexagonal packing to cubic packing conversion and at a temperature below, preferably greater than 100 ° C. below, more preferably by more than 150 ° C. below, very particularly preferably by more than 200 ° C. below the solidus temperature,
    • wherein the phase transition temperature is the temperature at which phase transition of the primary phase of the blank occurs, and the solidus temperature is the temperature at which melting of the lowest melting point phase in the blank occurs
  and / or wherein in step b) the heat treatment at a temperature in the range of 950 ° C to 1300 ° C, preferably in the range of 1000 ° C to 1250 ° C, and / or wherein in step b) the heat treatment at a pressure of less than 5 MPa, preferably less than 0.5 MPa, and / or wherein in step b) the heat treatment, preferably the heat treatment at the maximum treatment temperature, for a duration in the range of 15 to 240 minutes, preferably in the range of 30 to 180 minutes, more preferably in the range of 45 to 120 minutes, and / or wherein after step b) cooling of the blank within less than 20 minutes, preferably within less than 10 minutes, more preferably within less than 5 min , to a temperature which, measured in the center of gravity of the blank, below 50% of the indicated in ° C solidus temperature, in a blank with the main components cobalt and chromium preferably below 700 ° C. lie t, and / or wherein in step b) the heat treatment of the blank and / or after step b) cooling of the blank takes place in an inert gas stream or in a vacuum,
  • wherein preferably the inert gas is selected from the group consisting of nitrogen, helium argon and mixtures thereof.
• 4. The method according to one of the preceding aspects, wherein the blank after step b), preferably both after step a) and after step b), on the surface has an arithmetic mean roughness R _a , which is smaller than 3.2 microns, preferably smaller than 1.6 μm.
• 5. A method according to any one of the preceding aspects, wherein the metallic workpiece used in step a) is a disc, the method of making the same comprising one or more steps or step combinations selected from the group consisting of:
  • Casting a molten metal to the disk or preform,
  • Separating the disc from a preform, preferably by a separating manufacturing method selected from the group consisting of sawing, wire EDM, laser cutting and water jet cutting,
  • Pressure forming of the disc or a preform, preferably forging or rolling,
  • Shaping the disc by casting a molten metal and pressure forming, preferably forging or rolling, the resulting casting,
  • Shaping the pane by casting a molten metal into a preform and separating it out of the preform, preferably by a separating manufacturing process selected from the group consisting of sawing, wire eroding, laser cutting and water jet cutting,
  • Forming the disk by casting a molten metal into a preform, press-forming the preform, separating the disk from the pressure-formed preform, wherein the pressure forming is preferably a forging or rolling, the severing preferably being a separating manufacturing process selected from the group consisting of saws, Wire EDM, laser cutting and water jet cutting,
  • Forming the disk by casting a molten metal into a preform, separating the disk from the preform, and pressure forming the disk, wherein the pressure forming is preferably forging or rolling, wherein the severing is preferably a parting manufacturing process selected from the group consisting of sawing, wire eroding , Laser cutting and water jet cutting and
  • Forming the disc by powder metallurgy producing a preform, preferably by hot isostatic pressing of powder, and separating out the disc from the preform, wherein the separating is preferably a separating manufacturing method selected from the group consisting of sawing, wire EDM, laser cutting and water jet cutting.
• 6. A method according to any one of the preceding aspects, further comprising after step b) to ensure the quality and / or to facilitate the visual inspection of the quality of the surface of the blank, the step c) treating the surface of the blank with one or more methods selected from Group consisting of electrochemical processes, chemical processes, mechanical processes and their combinations, preferably electrochemical processes,
  • wherein the electrochemical processes are preferably selected from the group consisting of coating, electropolishing and plasma polishing, particularly preferably electropolishing and plasma polishing, very particularly preferably plasma polishing, the chemical processes preferably being selected from the group consisting of coating and pickling and the mechanical processes preferably are selected from the group consisting of coating, brushing, polishing and grinding.
• 7. A method according to aspect 6, comprising after step b) the step of ensuring the quality and / or facilitating the visual inspection of the quality of the surface of the blank
  • c) treating the surface of the blank with one or more methods selected from the group consisting of electropolishing and plasma polishing, wherein by this treatment the surface hardness of the blank produced or provided in step b) is increased by not more than 10% and / or wherein the Blank after step c) on the surface has an arithmetic mean roughness R _a , which is smaller than 0.8 microns, preferably less than 0.4 microns, more preferably less than 0.1 microns and / or wherein the surface of the blank after step c) is free from tarnish layers and / or scale layers and / or wherein the surface of the blank after step c) has a gloss value of at least 75 GE, preferably of at least 125 GE, more preferably of at least 250 GE, most preferably of at least 350 GE and especially preferably of at least 450 GE, measured by measuring the directional reflectance at 20 ° according to DIN EN ISO 7668: 2011-03 ,
• 8. Method according to aspect 7, wherein the treatment of the surface of the blank in step c)
  • by plasma polishing the blank, setting one, several or all of the following parameters:
    • Voltage: 270 to 400 V DC, preferably 280 to 360 V DC,
    • Current density: 0.1 to 1 A / cm ² , preferably 0.15 to 0.5 A / cm ² ,
    • Processing time: 1 to 10 min; preferably 1.5 to 5 minutes,
    • Electrolyte temperature: 50 to 98 ° C, preferably 65 to 90 ° C,
    • Electrolyte: aqueous electrolyte solution having an electrolyte concentration of 2 to 12% by weight, the electrolyte preferably being an ammonium salt,
    • pH: 1 to 7, preferably 4.5 to 6.5
    or by electropolishing the blank, adjusting one, several or all of the following parameters:
    • Voltage: 2 to 60 V DC, preferably 5 to 40 V DC, particularly preferably 7 to 20 V DC,
    • Current density: 0.05 to 3 A / cm ² , preferably 0.075 to 0.5 A / cm ² ,
    • Electrolyte temperature: 20 to 80 ° C, preferably 40 to 70 ° C,
    • Electrolyte: 90% by weight of glycerol with 10% by weight of sulfuric acid,
    • Processing time: 1 to 25 minutes, preferably 5 to 15 minutes.
• 9. The method of any preceding aspect, wherein the metallic workpiece is a dental alloy, wherein the dental alloy preferably comprises one or more elements selected from the group consisting of iron, gold, cobalt, chromium, copper, molybdenum, nickel, Palladium, platinum, silver, titanium, tungsten, tin, zinc, rhenium, indium, gallium, tantalum and rhodium, the dental alloy particularly preferably being a cobalt-chromium alloy, the dental alloy preferably containing cobalt in an amount of 35% by weight. up to 70% by weight, preferably in an amount of 50% by weight to 70% by weight, chromium in an amount of 17% by weight to 35% by weight, preferably in an amount of 20% by weight to 32% by weight Tungsten in an amount of 0 to 20 wt.%, Preferably in an amount of 0 to 12 wt.%, And molybdenum in an amount of 0 wt.% To 15 wt.%, Preferably in an amount of 0 wt. contains up to 10% by weight, very particularly preferably in an amount of 3% by weight to 8% by weight, in each case based on a On the total mass of the dental alloy, and / or wherein the sum of effective [Cr] + 3.3 (0.5 * [W] + [Mo])> 40, preferably> 45.
• 10. Method according to one of the preceding aspects, wherein the metallic workpiece consists of a dental alloy whose hardness increases during plastic deformation, wherein preferably in the tensile test, the fracture of the dental alloy takes place when the maximum load is measured in the load / elongation diagram, measured according to ISO 22674-2016.
• 11. Method according to one of the preceding aspects, wherein step b) is carried out such that the blank produced in step b) and / or the blank produced in step c) has at least partially an austenitic structure,
  • wherein the austenitic phase is preferably present in an amount of at least 50% by volume, more preferably at least 66% by volume, most preferably 90% by volume, based on the total volume of the blank
  and / or in step b) an austenitic phase is generated or the proportion of an austenitic phase is increased.
• 12. Method according to one of the preceding aspects, for producing a dental component, preferably a dental prosthesis part or dental auxiliary part, with the following additional step:
  • d) forming the component by means of a subtractive CAD / CAM method from the blank produced in step b) or step c) or a subsequent step,
    • preferably using a roughing cutter, preferably a torus milling cutter, particularly preferably a 3 mm torus milling cutter.
• 12A. Method according to aspect 12, wherein in step d) a roughing cutter is used, preferably a torus milling cutter, wherein the roughing cutter
  • has a defined cutting edge and / or
  • made of solid carbide and / or
  • coated with a coating, the coating preferably being applied by means of a PVD process,
  • wherein the coating preferably comprises a compound selected from the group consisting of TiN, TiAlN and AlCrN or
  • wherein the coating comprises CBN fine grain in a metallic binder phase
  and / or wherein in step d) the component is formed by means of a subtractive CAD / CAM process in two or more steps, wherein in the first step a roughing cutter, preferably a torus cutter is used and wherein in the second step or in one or several of the further steps a finishing mill, preferably a Stirnradiusfräser is used, which is finer than the roughing cutter.
• 13. A metallic blank for the production of dental components by means of a subtractive CAD / CAM method, wherein the blank has a quotient surface hardness to core hardness, which is smaller than 1.2 and at the surface has an arithmetic mean roughness R _a , which is smaller than zero , 8 microns and / or wherein the blank can be produced by a method according to any of aspects 1 to 11.
• 14. blank according to aspect 13, wherein the blank has a (mean) surface hardness of 200 HV10 to 400 HV10, preferably from 250 to 350 HV10, more preferably from 260 HV10 to 300 HV10 and / or wherein the blank has a quotient surface hardness to core hardness which is less than 1.1, preferably less than 1.05 and / or wherein the blank has on the surface an arithmetic mean roughness R _a which is less than 0.4 μm, preferably less than 0.1 μm and / or wherein the surface of the blank is free from tarnish layers and / or scale layers and / or wherein the surface of the blank after step c) has a gloss value of at least 75 GE, preferably of at least 125 GE, more preferably of at least 250 GE, most preferably of at least 350 GE, and more preferably at least 450 GE, measured by measuring the directional reflectance at 20 ° DIN EN ISO 7668: 2011-03 and / or wherein the blank at least partially has an austenitic structure,
  • wherein the austenitic phase is preferably present in an amount of at least 50% by volume, more preferably at least 66% by volume, most preferably 90% by volume, based on the total volume of the blank,
  and / or wherein the mean grain size of the blank in the range of 10 .mu.m to 500 .mu.m, preferably in the range of 20 .mu.m to 200 .mu.m, more preferably in the range of 50 .mu.m to 100 .mu.m, and / or wherein the blank has a maximum pore size which is smaller than 100 μm, preferably is smaller than 10 microns, more preferably less than 1 micron and / or wherein the blank has a porosity which is less than 5%, preferably less than 1%, more preferably less than 0.1%, based on the Total volume of the blank and / or wherein in the blank, the total volume fraction of precipitates consisting of intermetallic compounds, carbides or nitrides, less than 10 vol .-%, preferably 2.5 vol .-% particularly preferably 1 vol .-%, based on the total volume of the blank, and / or wherein the blank is made of a dental alloy, wherein the dental alloy preferably comprises one or more elements selected from the group consisting of iron, gold, cobalt, chromium, copper, molybdenum, nickel, palladium , Platinum, silver, titanium, tungsten, tin, zinc, rhenium, indium, gallium, tantalum and rhodium, the dental alloy particularly preferably being a cobalt-chromium alloy,
  • wherein the dental alloy preferably cobalt in an amount of 35 wt.% To 70 wt.%, Preferably in an amount of 50 wt.% To 70 wt.%, Chromium in an amount of 17 wt.% To 35 wt.%, Preferably in an amount of 20% by weight to 32% by weight, tungsten in an amount of 0 to 20% by weight, preferably in an amount of 0 to 12% by weight and molybdenum in an amount of 0% by weight to 15 % By weight, preferably in an amount of from 0% by weight to 10% by weight, very particularly preferably in an amount of from 3% by weight to 8% by weight, based in each case on the total mass of the dental alloy, and / or
  • wherein the effective sum is [Cr] + 3.3 (0.5 * [W] + [Mo])> 30, preferably> 40, particularly preferably> 45
  and / or wherein the blank is made of a dental alloy whose hardness increases with plastic deformation,
  • wherein preferably in the tensile test, the fracture of the dental alloy takes place when the maximum load is measured in the load / elongation diagram, measured according to ISO 22674-2016
  and / or wherein the blank has the following dimensions:
  • Circle diameter of a round blank or edge length of a rectangular blank: 15 to 250 mm, preferably 75 to 150 mm and
  • Height: 5 to 30 mm; preferably 7.5 to 25 mm.
• 15. Kit for producing dental components by CAD / CAM milling method comprising one or more blanks according to one of the aspects 13 or 14 and one or more roughing cutters.
• 15A. Kit according to aspect 15, wherein the one or more roughing cutters are torus cutters and / or have a defined cutting edge and / or consist of solid carbide and / or coated with a coating, the coating preferably being applied by means of a PVD process,
  • wherein the coating preferably comprises a compound selected from the group consisting of TiN, TiAlN and AlCrN or
  • wherein the coating comprises CBN fine grain in a metallic binder phase.
• 16. Use of a blank according to one of the aspects 13 or 14, in the manufacture of dental components by means of subtractive CAD / CAM methods, to increase the service life of the tool used in the subtractive CAD / CAM method, preferably a roughing cutter, particularly preferably a torus milling cutter.
• 17. Use of a heat treatment in the manufacture of a high workability ingot for the manufacture of dental components by subtractive CAD / CAM processes, wherein the surface hardness of the ingot before the heat treatment is higher than its core hardness, wherein the heat treatment of the blank is performed by stress relieving or solution annealing, preferably solution heat treatment takes place,
  • wherein stress relief annealing is preferably carried out at a temperature in the range of 50 to 70% of the solidus temperature indicated in ° C, and wherein the solution heat treatment is preferably at a temperature above the phase transition temperature of the hexagonal packing to cubic packing conversion and at a temperature below the solidus temperature;
    • wherein the phase transition temperature is the temperature at which phase transition of the primary phase of the blank occurs, and the solidus temperature is the temperature at which melting of the lowest melting point phase in the blank occurs,
  • wherein the heat treatment of the blank is carried out at a pressure of less than 5 MPa.
• 18. Use according to aspect 17 wherein the stress relief annealing temperature is selected so that there is no phase separation in the blank, and wherein the solution annealing at a temperature of more than 50 ° C above, preferably more than 100 ° C above, the Phase transition temperature of the conversion from the hexagonal packing to the cubic packing and at a temperature of more than 100 ° C below, preferably by more than 150 ° C below, more preferably by more than 200 ° C, below the solidus temperature,
  • wherein the phase transition temperature is the temperature at which phase transition of the primary phase of the blank occurs, and the solidus temperature is the temperature at which melting of the lowest melting point phase in the blank occurs
  and / or wherein the heat treatment is carried out at a temperature in the range of 950 ° C to 1300 ° C, more preferably in the range of 1000 ° C to 1250 ° C, and / or wherein the heat treatment of the blank at a pressure of less than 0, 5 MPa and / or wherein the heat treatment of the blank, preferably the heat treatment of the blank at the maximum treatment temperature, for a duration in the range of 15 to 240 minutes, preferably in the range of 30 to 180 minutes, more preferably in the range of 45 to 120 Minutes, and / or wherein after the blank has been heat-treated, the blank is cooled to less than 20 minutes, preferably less than 10 minutes, more preferably less than 5 minutes, to a temperature measured at the center of mass of the blank, is below 50% of the specified in ° C solidus temperature, in a blank with the main components cobalt and chromium preferably below 700 ° C. and / or wherein the heat treatment and / or cooling of the blank takes place in an inert gas stream or in a vacuum,
  • wherein preferably the inert gas is selected from the group consisting of nitrogen, helium, argon and mixtures thereof.
• 19. Use of an electrochemical process in cleaning, preferably cleaning of oxidic materials, and / or smoothing of a blank for the production of dental components by means of subtractive CAD / CAM processes, wherein the blank has a quotient of surface hardness to core hardness prior to the electrochemical process. which is less than 1.2 and wherein the surface hardness of the blank is increased by not more than 10% by the electrochemical method.
• 20. Use according to aspect 19, wherein the electrochemical process is selected from the group consisting of electropolishing and plasma polishing, preferably plasma polishing,
  • wherein in plasma polishing preferably one, several or all of the following parameters are set:
    • Voltage: 270 to 400 V DC, preferably 280 to 360 V DC,
    • Current density: 0.1 to 1 A / cm ² , preferably 0.15 to 0.5 A / cm ² ,
    • Processing time: 1 to 10 min; preferably 1.5 to 5 minutes,
    • Electrolyte temperature: 50 to 98 ° C, preferably 65 to 90 ° C,
    • Electrolyte: aqueous electrolyte solution having an electrolyte concentration of 2 to 12% by weight, the electrolyte preferably being an ammonium salt,
    • pH: 1 to 7, preferably 4.5 to 6.5
    and
  • wherein during electropolishing preferably one, several or all of the following parameters are set:
    • Voltage: 2 to 60 V DC, preferably 5 to 40 V DC, particularly preferably 7 to 20 V DC,
    • Current density: 0.05 to 3 A / cm ² , preferably 0.075 to 0.5 A / cm ² ,
    • Electrolyte temperature: 20 to 80 ° C, preferably 40 to 70 ° C,
    • Electrolyte: 90% by weight of glycerol with 10% by weight of sulfuric acid,
    • Processing time: 1 to 25 minutes, preferably 5 to 15 minutes
    and / or wherein the blank has an arithmetic mean roughness R _a at the surface after the electrochemical process which is less than 0.8 μm, preferably less than 0.4 μm, particularly preferably less than 0.1 μm, and / or wherein the surface of the blank according to the electrochemical process is free from tarnish layers and / or scale layers and / or wherein the surface of the blank after step c) a gloss value of at least 75 GE, preferably of at least 125 GE, more preferably of at least 250 GE, whole particularly preferably of at least 350 GE and especially preferably of at least 450 GE, measured by measuring the directional reflectance at 20 ° accordingly DIN EN ISO 7668: 2011-03 ,

Examples

The invention will be explained in more detail by way of examples.

Blanks produced by the process according to the invention and non-inventive comparative blanks were milled with a Work NC template for crowns and bridges. In the milling trials a Röders RXD5-C (FUE201) milling machine was used as a machine tool, with a 3 mm torus milling cutter (TR_3_14_0.4_CC-TI - 2636AZ.300614 from EMUGE FRANKEN) being used as roughing cutter.

The disk-shaped metallic workpieces on which the corresponding blanks were based were each obtained by singulation from a cast and hot-formed preform. The metallic workpieces each consisted of an alloy having an average composition Co64.5 Cr24.5 W5.1 Mo4.8 Si0.9 (with a target value of Co63.8 Cr24.8 W5.3 Mo5.1 Si1.0)). Based on the amount of substance of the present atoms, the total amount of impurities was not more than 0.5%, with not more than 0.1% Fe, not more than 0.1% Mn, not more than 0.1% Ni, not more than 0.02% Be, not more than 0.02% Cd, not more than 0.02% Pb, and not more than 0.1% other polluting elements. The solidus temperature of the metallic workpieces was 1380 ° C.

All the tests described below were carried out on disks of the composition indicated above.

Two series of blanks R1 and R2 according to the invention were produced using the method according to the invention from the above-described metallic workpieces of the stated composition. This means that the individual metal workpieces (blanks) described above were first turned off in a first step (a) to a thickness of 12 mm, i. that the surface of the metallic workpieces was machined by the machining method of turning before heat treatment of the machined workpieces at 1100 ° C for 1.5 hours in a second step (b) to reduce their surface hardness.

• H1.1 Kernhärte 250 - 300 HV10; Mittelwert 285 HV10, Oberflächenhärte 250 - 300 HV10; Mittelwert 285 HV10,
• H1.2 Kernhärte 250 - 300 HV10; Mittelwert 285 HV10 Oberflächenhärte 250 - 300 HV10; Mittelwert 285 HV10

On further disks of the same partial charge from which the blanks were taken from R1 and R2, the following hardness values were determined:

• H1.1 core hardness 250 - 300 HV10; Average value 285 HV10, surface hardness 250 - 300 HV10; Mean value 285 HV10,
• H1.2 core hardness 250 - 300 HV10; Average value 285 HV10 Surface hardness 250 - 300 HV10; Mean 285 HV10

To prepare two series of comparative blanks R3 and R4 not according to the invention, the above-described singulated metal workpieces of the stated composition were first subjected to a heat treatment at 1100 ° C. for 1.5 hours in a first step before the heat-treated workpieces (blanks) in a second Stepped to the desired thickness of 12 mm. Decisive for the comparative blanks not according to the invention is that no heat treatment took place after the machining. To carry out as meaningful as possible experiments, the heat treatment was deliberately not completely deleted, but preceded by inversion of the process steps of the method according to the invention the twisting. In this way, it is possible to show that the observed effect is not just an effect of the heat treatment that it has regardless of the process design. Thus, it is proved that only the specific order of the method steps of the method according to the invention, which causes the technical effect. The person skilled in the art is aware that the technical effect of the series R1 and R2 according to the invention, which is observed in comparison to the series with the comparative blanks R3 and R4, also corresponds to those blanks which are based on the above described, isolated metallic workpieces only by twisting, ie without any heat treatment produced.

• H2.1: Kernhärte 250 - 300 HV10; Mittelwert 285 HV10 Oberflächenhärte 460 - 590 HV 10; Mittelwert 520 HV 10
• H2.2: Kernhärte 250 - 300 HV10; Mittelwert 285 HV10 Oberflächenhärte 440 - 470 HV 10, Mittelwert 450 HV 10

On further disks of the same batch of parts, from which the blanks were taken to R3 and R4, the following hardness values were determined:

• H2.1: core hardness 250 - 300 HV10; Average value 285 HV10 Surface hardness 460 - 590 HV 10; Average value 520 HV 10
• H2.2: core hardness 250 - 300 HV10; Average value 285 HV10 Surface hardness 440 - 470 HV 10, average 450 HV 10

The milling trials were stopped after wear of the 3 mm torus cutter. The number of generated units was noted. The results are summarized in Table 1 below. Table 1: Number of units produced from the blanks: test series R1 R2 R3 R4 Number of generated units 240 270 211 210

The test results summarized in Table 1 clearly demonstrate the surprising effect that blanks according to the invention produced by the process according to the invention exhibit a significantly improved processability. From corresponding blanks according to the invention or blanks which were produced by the method according to the invention, significantly more units can be produced by means of CAD / CAM processes before wear of the tool used (torus milling cutters), than with the comparative blanks of the series R3 not according to the invention and R4.

The blanks of the series R1 and R2 according to the invention can thus be processed more easily and with less use of tools by machining methods, in particular with subtractive CAD / CAM methods.

The use of the blanks of the series R1 and R2 according to the invention in a subtractive CAD / CAM method thus results, as can be seen from Table 1, in a method for producing a dental component by means of subtractive CAD / CAM methods, which is characterized by a reduced mechanical load and correspondingly increased service life of the tools used (Torusfräser) characterized, whereby the production of corresponding components in high quantities is possible, at the same time particularly high work and process safety and reduced accumulated waste.

It has been found in further investigations that a cleaning or smoothing of the blanks of the series R1 and R2 produced according to the invention by means of electrochemical processes (electropolishing or plasma polishing) -as opposed to conventional cleaning / smoothing with machining processes such as, for example, turning surprisingly, those described above technical effect is not adversely affected, so that particularly smooth and clean blanks can be obtained with the preferred method according to the invention, the light, eg can be checked for their quality by means of visual control and still show the surprising technical effect.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005045698 A1 [0005]
• EP 1972322 B1 [0007]
• DE 102013003434 A1 [0008]
• DE 10342231 A1 [0009]
• DE 19714178 A1 [0010]
• DE 10309795 A1 [0011]
• EP 1764062 B1 [0012]
• WO 0207911 A1 [0012]
• WO 2013167905 [0013]
• DE 202008011646 U1 [0013]
• DE 102005043842 A1 [0092]

Cited non-patent literature

• "Material Science of Dental Materials 1" by R. Strietzel, (2016, Verlag Neuer Merkur GmbH, ISBN: 978-3-95409-037-2) [0005]
• "Goodbye? Precious metal-free dental materials in the CAD / CAM era "in quintessence Zahntech 2006; 32 (9): 1012-1019 and B. Karpuschewski et al. [0006]
• "CoCr Is Not the Same: CoCr Blanks for Dental Machining" in G-shoe el al. (eds.), "Future Trends in Production Engineering" (DOI 10.1007 / 978-3-642-24491-9_26, Springer-Verlag Berlin Heidelberg 2013) [0006]
• K. Nestler et al, Procedia CIRP 42 (2016) 503-507 [0013]
• Zeidler et al, Procedia CIRP 49 (2016) 83-87 [0013]
• "Handbook" by U. Heisel et al. (Karl Hanser Verlag Munich, 2014, pages 1228 ff. [0013]
• H. Zeidler et al. "Use of additive manufacturing processes and plasma electrolytic surface treatment in medical technology", held at the Biosaxony "Medizintechnik in Sachsen", Chemnitz 2016 [0013]
• R. Riquier and M. Krause in Quintessenz Zahntech 2011; 37 (5): 628-639 [0014]
• DIN EN ISO 6501-1 [0034]
• DIN EN ISO 6507-1: 2006 [0034]
• DIN EN ISO 6507-4: 2006 [0034]
• DIN EN ISO 7668: 2011-03 [0073, 0099, 0117, 0119]

Claims (13)

Method for producing a blank for the production of dental components by means of subtractive CAD / CAM methods or for producing a dental component from such a blank, comprising the steps: a) producing a blank from a metallic workpiece by machining at least areas of the workpiece surface or providing such a blank, wherein the surface hardness of the prepared or provided blank is higher than its core hardness and the machining is selected from the group consisting of turning, grinding and milling, b) heat treating the blank produced or provided in step a) so as to reduce at least the surface hardness of the blank produced or provided. Method according to Claim 1 , wherein in step b) the ratio of surface hardness to core hardness is reduced, wherein the blank after step b) preferably has a quotient surface hardness to core hardness which is less than 1.2; preferably less than 1.1; more preferably less than 1.05. Method according to one of the preceding claims, wherein in step b) the heat treatment is carried out by stress relief annealing or solution annealing, preferably by solution annealing, wherein the stress relief annealing is preferably carried out at a temperature in the range of 50 to 70% of the solidus temperature indicated in ° C, wherein the temperature is preferably selected so that there is no phase separation in the blank and wherein solution heat treatment is preferably at a temperature above, preferably greater than 50 ° C above, more preferably greater than 100 ° C above, the phase transition temperature of the hexagonal packing to cubic packing conversion and at a temperature below, preferably greater than 100 ° C. below, more preferably by more than 150 ° C. below, very particularly preferably by more than 200 ° C. below the solidus temperature, wherein the phase transition temperature is the temperature at which phase transition of the primary phase of the blank occurs, and the solidus temperature is the temperature at which melting of the lowest melting point phase in the blank occurs and / or wherein in step b) the heat treatment at a temperature in the range of 950 ° C to 1300 ° C, preferably in the range of 1000 ° C to 1250 ° C, takes place and or wherein in step b) the heat treatment is carried out at a pressure of less than 5 MPa, preferably less than 0.5 MPa and or wherein in step b) the heat treatment, preferably the heat treatment at the maximum treatment temperature, for a duration in the range of 15 to 240 minutes, preferably in the range of 30 to 180 minutes, particularly preferably in the range of 45 to 120 minutes and or wherein after step b) cooling of the blank within less than 20 minutes, preferably within less than 10 minutes, more preferably within less than 5 minutes, to a temperature which, measured in the center of mass of the blank, below 50% of in ° C indicated solidus, is in a blank with the main components cobalt and chromium preferably below 700 ° C, and / or wherein in step b) the heat treatment of the blank and / or after step b) a cooling of the blank takes place in an inert gas stream or in a vacuum, wherein preferably the inert gas is selected from the group consisting of nitrogen, helium argon and mixtures thereof. Method according to one of the preceding claims, wherein the metallic workpiece used in step a) is a disc, the method for their preparation comprises one or more steps or step combinations, which are selected from the group consisting of: - pouring a molten metal to the Disc or preform, - separating the disc from a preform, preferably by a separating manufacturing process selected from the Group consisting of sawing, wire EDM, laser cutting and water jet cutting, pressure forming of the disc or a preform, preferably forging or rolling, forming the disc by casting a molten metal and pressure forming, preferably forging or rolling, the resulting casting, forming the disc by casting a molten metal to a preform and separating the disc from the preform, preferably by a separating manufacturing process selected from the group consisting of sawing, wire EDM, laser cutting and water jet cutting, - forming the disc by casting a molten metal into a preform, pressure forming of the preform, separating the A disk of the pressure-formed preform, wherein the pressure forming is preferably a forging or rolling, wherein the severing is preferably a separating manufacturing process selected from the group consisting of sawing, wire eroding, laser cutting and water jet cutting, - forming the disk by casting a molten metal into a preform, separating the disk from the preform and pressure forming the disk, wherein the pressure forming is preferably a forging or rolling, the severing is preferably a separating manufacturing process selected from the group consisting of Sawing, wire EDM, laser cutting and water jet cutting, and - forming the disc by powder metallurgy producing a preform, preferably by hot isostatic pressing of powder, and separating the disc from the preform, wherein the severing is preferably a separating manufacturing process selected from the group consisting of sawing, wire eroding , Laser cutting and water jet cutting. A method according to any one of the preceding claims additionally comprising after step b) the step of ensuring the quality and / or facilitating the visual inspection of the quality of the surface of the blank c) treating the surface of the blank with one or more methods selected from the group consisting of electrochemical processes, chemical processes, mechanical processes and combinations thereof, preferably electrochemical processes, wherein the electrochemical processes are preferably selected from the group consisting of coating, electropolishing and plasma polishing, more preferably electropolishing and plasma polishing, very particularly preferably plasma polishing, wherein the chemical processes are preferably selected from the group consisting of coating and pickling and wherein the mechanical methods are preferably selected from the group consisting of coating, brushing, polishing and grinding. Method according to one of the preceding claims, wherein the metallic workpiece is made of a dental alloy, wherein the dental alloy preferably comprises one or more elements selected from the group consisting of iron, gold, cobalt, chromium, copper, molybdenum, nickel, palladium, platinum, silver, titanium, tungsten , Tin, zinc, rhenium, indium, gallium, tantalum and rhodium, the dental alloy particularly preferably being a cobalt-chromium alloy, wherein the dental alloy preferably cobalt in an amount of 35 wt.% To 70 wt.%, Preferably in an amount of 50 wt.% To 70 wt.%, Chromium in an amount of 17 wt.% To 35 wt.%, Preferably in an amount of 20% by weight to 32% by weight, tungsten in an amount of 0 to 20% by weight, preferably in an amount of 0 to 12% by weight and molybdenum in an amount of 0% by weight to 15 % By weight, preferably in an amount of from 0% by weight to 10% by weight, very particularly preferably in an amount of from 3% by weight to 8% by weight, based in each case on the total mass of the dental alloy, and or where the effective sum is [Cr] + 3.3 (0.5 * [W] + [Mo])> 40, preferably> 45. and or wherein the metallic workpiece consists of a dental alloy whose hardness increases with plastic deformation, wherein preferably in the tensile test, the fracture of the dental alloy takes place when the maximum load is measured in the load / elongation diagram, measured according to ISO 22674-2016. Method according to one of the preceding claims, wherein step b) is carried out such that the blank produced in step b) and / or the blank produced in step c) has at least partially an austenitic structure, wherein the austenitic phase is preferably present in an amount of at least 50% by volume, more preferably at least 66% by volume, most preferably 90% by volume, based on the total volume of the blank and / or In step b) an austenitic phase is generated or the proportion of an austenitic phase is increased. Method according to one of the preceding claims, for producing a dental component, preferably a dental prosthesis part or dental auxiliary part, with the following additional step: d) forming the component by means of a subtractive CAD / CAM method from the blank produced in step b) or step c) or a subsequent step, preferably using a roughing cutter, preferably a torus milling cutter, particularly preferably a 3 mm torus milling cutter. A metallic blank for the production of dental components by means of a subtractive CAD / CAM method, wherein the blank has a quotient surface hardness to core hardness which is smaller than 1.2 and at the surface has an arithmetic mean roughness R _a which is smaller than 0.8 μm and / or wherein the blank can be produced by a method according to one of Claims 1 to 8th , Blank after Claim 9 wherein the blank has a quotient surface hardness to core hardness which is less than 1.1, preferably less than 1.05 and / or wherein the blank on the surface has an arithmetic mean roughness R _a , which is smaller than 0.4 microns, preferably less than 0.1 microns and / or wherein the surface of the blank is free of tarnish layers and / or scale layers and / or wherein the Surface of the blank after step c) has a gloss value of at least 75 GE, preferably of at least 125 GE, more preferably of at least 250 GE, most preferably of at least 350 GE and especially preferably of at least 450 GE measured by measuring the directional reflectance at 20 ° according to DIN EN ISO 7668: 2011-03 and / or wherein the blank at least partially has an austenitic structure, the austenitic phase preferably in an amount of at least 50 vol.%, Particularly preferably at least 66 vol.%, Especially preferably 90 vol.%, Is present, based on the total volume of the blank, and / or wherein the average grain size of the blank in the range of 10 microns to 50 0 μm, preferably in the range from 20 μm to 200 μm, particularly preferably in the range from 50 μm to 100 μm, and / or wherein the blank has a maximum pore size which is smaller than 100 μm, preferably smaller than 10 μm, more preferably less than 1 micron and / or wherein the blank has a porosity which is less than 5%, preferably less than 1%, more preferably less than 0.1%, based on the total volume of the blank and / or wherein in the blank the total volume fraction of precipitations consisting of intermetallic compounds, carbides or nitrides is less than 10% by volume, preferably 2.5% by volume, more preferably 1% by volume, based on the total volume of the blank, and / or wherein the blank is made of a dental alloy, wherein the dental alloy preferably comprises one or more elements selected from the group consisting of iron, gold, cobalt, chromium, copper, molybdenum, nickel, palladium, platinum, S ilber, titanium, tungsten, tin, zinc, rhenium, indium, gallium, tantalum and rhodium, wherein the dental alloy is particularly preferably a cobalt-chromium alloy, wherein the dental alloy is preferably cobalt in an amount of 35 wt.% To 70 wt. %, preferably in an amount of 50% by weight to 70% by weight, chromium in an amount of 17% by weight to 35% by weight, preferably in an amount of 20% by weight to 32% by weight, tungsten in one From 0 to 20% by weight, preferably from 0 to 12% by weight, and molybdenum from 0% to 15% by weight, preferably from 0% to 10% by weight. %, very particularly preferably in an amount of from 3% by weight to 8% by weight, based in each case on the total mass of the dental alloy, and / or wherein the effective sum is [Cr] + 3.3 (0.5 * [W] + [Mo])> 30, preferably> 40, particularly preferably> 45, and / or wherein the blank consists of a dental alloy whose hardness increases with plastic deformation, the break of the den tal alloy is then carried out when the maximum load is measured in the load / elongation diagram, measured according to ISO 22674-2016 and / or wherein the blank has the following dimensions: circle diameter of a round blank or edge length of a rectangular blank: 15 to 250 mm, preferably 75 to 150 mm and height: 5 to 30 mm; preferably 7.5 to 25 mm. Kit for the production of dental components by CAD / CAM milling method comprising one or more blanks according to one of Claims 9 or 10 and one or more roughing cutters. Using a blank after one of Claims 9 or 10 in the manufacture of dental components by means of subtractive CAD / CAM methods, to increase the service life of the tool used in the subtractive CAD / CAM method, preferably a roughing cutter, particularly preferably a torus cutter. Use of an electrochemical process in cleaning, preferably cleaning that eliminates oxidic materials, and / or smoothing of a blank for the production of dental components by means of subtractive CAD / CAM processes, wherein the blank before the electrochemical process has a quotient surface hardness to core hardness, which is less than 1.2 and wherein the surface hardness of the blank is increased by not more than 10% by the electrochemical method.