WO2021001730A1

WO2021001730A1 - Methods of making metal bond abrasive articles and metal bond abrasive articles

Info

Publication number: WO2021001730A1
Application number: PCT/IB2020/055979
Authority: WO
Inventors: Robert L. W. Smithson; Brian D. Goers; Brian K. Nelson; Jean-Luc RIFAUT
Original assignee: 3M Innovative Properties Company
Priority date: 2019-07-02
Filing date: 2020-06-24
Publication date: 2021-01-07

Abstract

A metal bond abrasive article comprises an abrasive member comprising a metal matrix containing abrasive particles; and a mounting member, wherein the mounting member extends into, and is directly fused to, the abrasive member. A method of making the metal bond abrasive particle involving powder bed binder jetting rapid prototyping is also disclosed.

Description

METHODS OF MAKING METAL BOND ABRASIVE ARTICLES

AND METAL BOND ABRASIVE ARTICLES

TECHNICAL FIELD

The present disclosure broadly relates to methods of making abrasive articles having abrasive particles in a metal matrix, and the abrasive articles made by the methods.

BACKGROUND

Traditionally, metal bond abrasive articles are manufactured by a compression method. Abrasive grits, such as diamond, aluminum oxide, cubic boron nitride (cBN), or other abrasive grains, are mixed with metal powders as a bond material, such as non-melting metal powders (e.g., tungsten, stainless steel, or others), melting metal powders (e.g., bronze or copper), or a combination thereof. Pore inducers (such as glass bubbles, naphthalene, crushed coconut or walnut shells), temporary binders (such as phenolic resin, urea formaldehyde resin, and dextrin) and other additives may be added. The mixture is then introduced into a mold that has been coated with a mold release agent. The fdled mold is then compressed in a press to form a molded green body. The green body then is ejected from the mold and subsequently heated in a furnace at high temperature to melt a portion of the metal composition, or it is infused with a molten metal. The heating is typically done in a suitable controlled atmosphere of inert or reducing gas (e.g., nitrogen, argon, hydrogen) or vacuum.

When metal bond abrasives need to be mounted to a mounting member (such as a shaft, a screw or other threaded stock), typically extra steps and/or materials (e.g., adhesive, adapters) are needed, and the process is usually labor intensive.

SUMMARY

Powder bed binder jetting is an additive manufacturing, or "3D printing" technology, in which a thin layer of a powder is temporarily bonded at desired locations by a jetted liquid binder mixture.

Typically, that binder mixture is dispensed by an inkjet printing head, and consists of a polymer dissolved in a suitable solvent or carrier solution. The printed powder layer is then at least partially dried and lowered so that a next powder layer can be spread. The powder spreading, bonding and drying processes can be repeated until the full object is created. The object and surrounding powder is removed from the printer and often dried or cured to impart additional strength so that the now hardened object can be extracted from the surrounding powder.

In a first aspect, the present disclosure provides a method of making a metal bond abrasive article, the method comprising the sequential steps:

a) a subprocess comprising sequentially:

i) depositing a layer of loose powder particles in a confined region, wherein the layer of loose powder particles comprises metal particles and abrasive particles, and wherein the layer of loose powder particles has substantially uniform thickness; ii) jetting a liquid binder precursor material onto at least one predetermined region of the layer of loose powder particles;

iii) converting the liquid binder precursor material into a binder material that bonds together the layer of loose powder particles in the at least one predetermined region to form a layer of bonded powder particles;

b) independently carrying out step a) a plurality of times to generate an abrasive preform

comprising the layer of bonded powder particles, wherein the abrasive preform comprises at least one opening extending into the abrasive preform;

c) separating substantially all of any loose powder particles from the abrasive preform;

d) inserting a mounting member at least partially into the opening;

e) sintering at least a portion of the metal particles in the abrasive preform while the mounting member is at least partially inserted in the opening to form the metal bond abrasive article.

In another aspect, the present disclosure provides a metal bond abrasive article comprising: an abrasive member comprising a metal matrix containing abrasive particles; and

a mounting member, wherein the mounting member extends into, and is directly fused to, the abrasive member.

Advantageously, bonded abrasive articles can be made simpler and more cost efficiently than conventional methods.

As used herein,

the term "directly fused" means fused in intimate contact; and

the term "substantially all" means at least 90 percent (e.g. at least 95 percent, at least 99 percent). Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic process flow diagram of a method of making an abrasive preform 190 according to the present disclosure.

FIG. 2 is a schematic process flow diagram of a method of making a metal bond abrasive article from abrasive preform 290 according to the present disclosure.

FIG. 3 is a schematic perspective view of an exemplary dental bur 300 preparable according a method of the present disclosure.

FIG. 4 is a schematic cross-sectional top view of an exemplary metal bond abrasive wheel 400 preparable according to the present disclosure.

FIG. 5 is a schematic cross-sectional top view of an exemplary metal bond abrasive wheel 500 preparable according to the present disclosure. Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.

DETAILED DESCRIPTION

Methods of making a metal bond abrasive articles according to the present disclosure include a common additive subprocess. The subprocess comprises sequentially, preferably consecutively (although not required) carrying out at least three steps.

FIG. 1 schematically depicts an exemplary powder bed jetting process 100 used in making a metal bond abrasive article.

In the first step, a layer 138 of loose powder particles 110 from powder chamber 120a with movable piston 122a is deposited in a confined region 140 in powder chamber 120b with movable piston 122b. The layer 138 should preferably be of substantially uniform thickness. For example, the thickness of the layer may vary less than 50 microns, preferably less than 30 microns, and more preferably less than 10 microns. The layers may have any thickness up to about 1 millimeter, as long as the jetted liquid binder precursor material can bind all the loose powder where it is applied. Preferably, the thickness of the layer is from about 10 microns to about 500 microns, more preferably about 10 microns to about 250 microns, more preferably about 50 microns to about 250 microns, and more preferably from about 100 microns to about 200 microns.

The loose powder particles comprise higher melting metal particles and abrasive particles.

The higher melting metal particles may comprise any metal from group 2 through to group 15 of the Periodic Table of the elements, for example. Alloys of these metals, and optionally with one or more elements (e.g., metals and/or non-metals such as carbon, silicon, boron) in groups 1 and 15 of the Periodic Table, may also be used. Examples of suitable metal particles include powders comprising magnesium, aluminum, iron, titanium, niobium, tungsten, chromium, tantalum, cobalt, nickel, vanadium, zirconium, molybdenum, palladium, platinum, copper, silver, gold, cadmium, tin, indium, tantalum, zinc, alloys of any of the foregoing, and combinations thereof.

The higher melting metal particles preferably having a melting point of at least about 1100° C, and more preferably at least 1200° C, although lower melting metals may also be used. Examples include stainless steel (about 1360-1450°C), nickel (1452°C), steel (1371°C), tungsten (3400°C), chromium (1615°C), Inconel (Ni+Cr+Fe, 1390-1425°C), iron (1530°C), manganese (1245-1260°C), cobalt (1132°C), molybdenum(2625°C), Monel (Ni+Cu, 1300-1350°C), niobium (2470°C), titanium (1670°C), vanadium (1900°C), antimony (1167°C), Nichrome (Ni+Cr, 1400°C), alloys of the foregoing (optionally also including one or more of carbon, silicon, and boron), and combinations thereof. Combinations of two or more different higher melting metal particles may also be used. The abrasive particles may comprise any abrasive material used in the abrasives industry, for example. Preferably, the abrasive particles have a Mohs hardness of at least 4, preferably at least 5, more preferably at least 6, more preferably at least 7, more preferably at least 8, more preferably at least 8.5, and more preferably at least 9. In certain embodiments, the abrasive particles comprise superabrasive particles. As used herein, the term "superabrasive" refers to any abrasive particle having a hardness greater than or equal to that of silicon carbide (e.g., silicon carbide, boron carbide, cubic boron nitride, and diamond).

Specific examples of suitable abrasive materials include aluminum oxide (e.g., alpha alumina) materials (e.g., fused, heat-treated, ceramic, and/or sintered aluminum oxide materials), silicon carbide, titanium diboride, titanium nitride, boron carbide, tungsten carbide, titanium carbide, aluminum nitride, diamond, cubic boron nitride, garnet, fused alumina-zirconia, sol-gel derived abrasive particles, cerium oxide, zirconium oxide, titanium oxide, and combinations thereof. Examples of sol-gel derived abrasive particles can be found in U.S. Pat. No. 4,314,827 (Leitheiser et al.); U.S. Pat. No. 4,623,364 (Cottringer et al.); U.S. Pat. No. 4,744,802 (Schwabel); U.S. Pat. No. 4,770,671 (Monroe et al.); and U.S. Pat. No. 4,881,951 (Monroe et al.). Agglomerate abrasive particles that comprise finer abrasive particles in a vitreous bond matrix (e.g., as described in U.S. Pat. No. 6,551,366 (D'Souza et al.)) may also be used.

The abrasive particles may be coated with a metal to facilitate bonding with other metallic components (higher and/or lower melting metal particles and/or infused metal) of the abrasive article; for example, as described in U.S. Pat. Appl. Publ. No. 2008/0187769 Al (Huzinec) or U.S. Pat. No.

2,367,404 (Kott).

In order to achieve fine resolution, the loose powder particles are preferably sized (e.g., by screening) to have a maximum size of less than or equal to 400 microns, preferably less than or equal to 250 microns, more preferably less than or equal to 200 microns, more preferably less than or equal to 150 microns, less than or equal to 100 microns, or even less than or equal to 80 microns, although larger sizes may also be used. The higher melting metal particles, abrasive particles, optional lower melting metal particles, and any optional additional particulate components may have the same or different maximum particle sizes, D90, D50, and/or D _| Q particle size distribution parameters.

The loose powder particles may optionally further comprise lower melting metal particles (e.g., braze particles). The lower melting metal particles preferably have a maximum melting point that is at least 50°C lower (preferably at least 75°C lower, at least 100°C, or even at least 150°C lower) than the lowest melting point of the higher melting metal particles. As used herein, the term "melting point" includes all temperatures in a melting temperature range of a material. Examples of suitable lower melting metal particles include particles of metals such as aluminum (660°C), indium (157°C), brass (905-1083°C), bronze (798-1083°C), silver (961°C), copper (1083°C), gold (1064°C), lead (327°C), magnesium (671°C), nickel (1452°C, if used in conjunction with higher melting point metals), zinc (419°C), tin (232°C), active metal brazes (e.g., InCuAg, TiCuAg, CuAg), alloys of the foregoing, and combinations thereof. Typically, the weight ratio of high melting metal particles and/or optional lower melting metal particles to the abrasive particles ranges from about 10:90 to about 90: 10, although this is not a requirement.

The loose powder particles may optionally further comprise other components such as, for example, pore inducers, fdlers, and/or fluxing agent particles. Examples of pore inducers include glass bubbles and organic particles. In some embodiments, the lower melting metal particles may also serve as a fluxing agent; for example as described in U.S. Pat. No. 6,858,050 (Palmgren).

The loose powder particles may optionally be modified to improve their flowability and the uniformity of the layer spread. Methods of improving the powders include agglomeration, spray drying, gas or water atomization, flame forming, granulation, milling, and sieving. Additionally, flow agents such as, for example, fumed silica, nanosilica, stearates, and starch may optionally be added.

Next, a liquid binder precursor material 170 is jetted by printer 150 onto predetermined region(s) 180 of layer 138. The liquid binder precursor material thus coats the loose powder particles in region 180, and is subsequently converted to a binder material that binds the loose powder particles in region 180 to each other. The liquid binder precursor material may be any composition that can be converted (e.g., by evaporation, or thermal, chemical, and/or radiation curing (e.g., using UV or visible light)) into a binder material that bonds the loose powder particles together according to the jetted pattern (and ultimate 3-D shape upon multiple repetitions).

In some embodiments, the liquid binder precursor material comprises a liquid vehicle having a polymer dissolved therein. The liquid may include one or more of organic solvent and water. Exemplary organic solvents include alcohols (e.g., butanol, ethylene glycol monomethyl ether), ketones, and ethers, preferably having a flash point above 100°C.

Selection of a suitable solvent or solvents will typically depend upon requirements of the specific application, such as desired surface tension and viscosity, the selected particulate solid, for example.

The liquid vehicle can be entirely water, or can contain water in combination with one or more organic solvents. Preferably, the aqueous vehicle contains, on a total weight basis, at least 20 percent water, at least 30 percent water, at least 40 percent water, at least 50 percent water, or even at least 75 percent water.

In some embodiments, one or more organic solvents may be included in the liquid vehicle, for instance, to control drying speed of the liquid vehicle, to control surface tension of the liquid vehicle, to allow dissolution of an ingredient (e.g., of a surfactant), or, as a minor component of any of the ingredients; e.g., an organic co-solvent may be present in a surfactant added as an ingredient to the liquid vehicle. Exemplary organic solvents include: alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol, and isobutyl alcohol;

ketones or ketoalcohols such as acetone, methyl ethyl ketone, and diacetone alcohol; esters such as ethyl acetate and ethyl lactate; polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, 1,2,4-butanetriol, 1,5-pentanediol, 1,2,6- hexanetriol, hexylene glycol, glycerol, glycerol ethoxylate, trimethylolpropane ethoxylate; lower alkyl ethers such as ethylene glycol methyl or ethyl ether, diethylene glycol ethyl ether, triethylene glycol methyl or ethyl ether, ethylene glycol n-butyl ether, diethylene glycol n-butyl ether, diethylene glycol methyl ether, ethylene glycol phenyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, tripropylene glycol n- propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, and dipropylene glycol dimethyl ether; nitrogen-containing compounds such as 2-pyrrolidinone and N-methyl-2-pyrrolidinone; sulfur-containing compounds such as dimethyl sulfoxide, tetramethylene sulfone, and thioglycol; and combinations of any of the foregoing.

The amounts of organic solvent and/or water within the liquid vehicle can depend on a number of factors, such as the particularly desired properties of the liquid binder precursor material such as the viscosity, surface tension, and/or drying rate, which can in turn depend on factors such as the type of ink jet printing technology intended to be used with the liquid vehicle ink, such as piezo-type or thermal -type printheads, for example.

The liquid binder precursor material may include a polymer that is soluble or dispersible in the liquid vehicle. Examples of suitable polymers may include polyvinyl pyrrolidones, polyvinyl caprolactams, polyvinyl alcohols, polyacrylamides, poly(2-ethyl-2-oxazoline) (PEOX), polyvinyl butyrate, copolymers of methyl vinyl ether and maleic anhydride, certain copolymers of acrylic acid and/or hydroxyethyl acrylate, methyl cellulose, natural polymers (e.g., dextrin, guar gum, xanthan gum). Of these, polyvinyl pyrrolidones are preferred for use with liquid vehicles that are predominantly water. Other organic polymers than those listed above may be used instead or in addition if desired.

The liquid binder precursor material may include one or more free-radically polymerizable or otherwise radiation-curable materials; for example, acrylic monomers and/or oligomers and/or epoxy resins. An effective amount of photoinitiator and/or photocatalysts for curing the free-radically polymerizable or otherwise radiation-curable materials may also be included. Examples of suitable (meth)acrylate monomers and oligomers and otherwise radiation-curable materials (e.g., epoxy resins) can be found in, for example, U.S. Pat. No. 5,766,277 (DeVoe et ah).

In some preferred embodiments, the liquid binder precursor material is essentially free of (e.g., contains less than 1 percent, less than 0.1 percent, less than 0.01 percent, or is even free of) inorganic components (other than water) that would not be volatilized during sintering of the higher and/or lower melting metal particles. The liquid binder precursor material may be free of metal nanoparticles and/or metal oxide nanoparticles, if desired. As used herein, the term "nanoparticles" refers to particles having an average particle diameter of less than or equal to one micron; for example less than or equal to 500 nanometers (nm), or even less than or equal to 150 nm.

Referring again to FIG. 1, the jetted liquid binder precursor material 170 is converted (step 190) into a binder material that bonds together the loose powder particles in at least one predetermined region of the loose powder particles to form a layer of bonded powder particles; for example, by evaporation of a liquid vehicle in the liquid binder precursor material. In these embodiments, heating the binder material to sufficiently high temperature causes it to volatilize and/or decompose (e.g., "bum out") during subsequent sintering or infusion steps.

The foregoing steps are then repeated (step 185) with changes to the region where jetting is carried out according to a predetermined design resulting through repetition, layer on layer, in a three- dimensional (3-D) abrasive article preform. In each repetition, the loose powder particles and the liquid binder precursor material may be independently selected; that is, either or both or the loose powder particles and the liquid binder precursor material may be the same as, or different from those in adjacent deposited layers. While individual layers of the loose powder particles may be jetted in any location, taken collectively, the jetting should be performed according to a predetermined pattern that provides an opening adapted to receive the mounting member. The opening should be large enough to accept the mounting member, but preferably only slightly larger (e.g., <1 mm larger in diameter) in order to achieve a secure bond after heating with shrinking of the abrasive article preform.

The abrasive article preform comprises the bonded powder particles and remaining loose powder particles. Once sufficient repetitions have been carried out to form the abrasive article preform, it is preferably separated from substantially all (e.g., at least 85 percent, at least 90 percent, preferably at least 95 percent, and more preferably at least 99 percent) of the remaining loose powder particles, although this is not a requirement.

If desired, multiple particle reservoirs each containing a different powder may be used. Likewise, multiple different liquid binder precursor materials may be used, either through a common printhead or, preferably, through separate printheads. This results in different powders/binders distributed in different and discrete regions of the metal bond abrasive article. For example, relatively inexpensive, but lower performing abrasive particles, metal powders, and or binder materials may be relegated to regions of the metal bond abrasive article where it is not particularly important to have high performance properties (e.g., in the interior away from the abrading surface). Referring now to FIG. 6, metal bond abrasive wheel 600 has two regions 610, 620. Each region has abrasive particles 630, 640 retained in a metal bond matrix material 650, 660, respectively.

The abrasive article preform is then heated (step 195 in FIG. 1) to remove any organic binder material and/or solvent that may be present, and sinter the metal particles, thereby providing the metal bond abrasive article. Heating may be accomplished by many techniques know to those of skill in the art including, for example, in a kiln or oven, or using a heat lamp.

Referring now to FIG. 2, abrasive preform 290 has opening 295 into which mounting member 220 (shown as a shaft) is inserted. Sintering then results in metal bond abrasive article 200 with mounting member 220 secured to the sintered abrasive preform 240. Further details concerning powder bed jetting techniques suitable for practicing the present disclosure can be found, for example, in U.S. Pat. Nos. 5,340,656 (Sachs et al.) and 6,403,002 B1 (van der Geest).

In embodiments in which the loose powder particles include higher melting metal particles and lower melting metal particles, the abrasive article preform may be heated sufficiently to cause the lower melting metal particles to soften/melt and bond to at least a portion of the loose powder particles, and then cooled to provide the metal bond abrasive article.

In embodiments in which the loose powder particles include higher melting metal particles and no lower melting metal particles, the abrasive article preform may be heated sufficiently to cause the higher melting metal particles to at least sinter and bond to at least a portion of the loose powder particles, and then cooled to provide the metal bond abrasive article.

Cooling may be accomplished by any means known to the art; for example cold quenching or air cooling to room temperature.

Metal bond abrasive articles and/or abrasive article preforms made according to the present disclosure may comprise a porous metal-containing matrix (e.g., which may comprise metal particles and abrasive particles, and which may be sintered) with considerable porosity throughout its volume, although this is not a requirement. For example, the porous metal-containing matrix may have a void fraction of 1 to 60 volume percent, preferably 5 to 50 volume percent, and more preferably 15 to 50 volume percent, more preferably 40 to 50 volume percent, although this is not a requirement. Accordingly, the abrasive article preform may then be infused with a molten metal that has a temperature below the melting point(s) of any other metallic components, then cooled. Examples of suitable metals that can be made molten and infused into the abrasive article preform include aluminum, indium, brass, bronze, silver, copper, gold, lead, cobalt, magnesium, nickel, zinc, tin, iron, chromium, silicon alloys, alloys of the foregoing, and combinations thereof.

Powder bed jetting equipment suitable for practicing the present disclosure is commercially available, for example, from ExOne, North Huntington, Pennsylvania.

Further details concerning sintering and then infusing with molten metal can be found in, for example, U.S. Pat. No. 2,367,404 (Kott) and U.S. Pat. Appln. Publ. No. 2002/095875 (D'Evelyn et al.).

Metal bond abrasive articles preparable according to methods of the present disclosure include, for example, grinding bits and abrasive wheels. In some preferred embodiments, the metal bond abrasive article comprises at least a portion of a rotary dental tool (e.g., a dental drill bit, a dental bur, or a dental polishing tool). An exemplary dental bur 300 is shown in FIG. 3. Referring now to FIG. 3, dental bur 300 includes head 330 secured to mounting member 320 (e.g., a shaft). Dental bur 300 comprises abrasive particles 305 secured in porous metal bond 310.

Exemplary mounting members include shafts and hubs, which may be smooth, threaded, or otherwise textured. Useful shafts may be cylindrical (smooth or notched), square, hexagonal, pentagonal, or star-shaped, for example. Useful hubs may have a shaft or threaded opening integrally formed therewith, for example.

The present disclosure to manufacture metal bonded abrasive articles, such as rotary grinding and polishing tools and wheels.

Advantageously, methods according to the present disclosure are suitable for manufacturing various metal bond abrasive articles that cannot be readily or easily fabricated by other methods. For example, inclusion of internal voids is possible as long as an opening to the exterior of the abrasive preform exists for removal of unbonded loose powder. Accordingly, cooling channels having tortuous and or arcuate paths can be readily manufactured using methods of the present disclosure. Cooling channels are open to the exterior of the metal bond abrasive article. In some embodiments, they have a single opening, but more typically they have two or more openings. A cooling medium (e.g., air, water or oil) circulates through the cooling channel(s) to remove heat generated during abrading.

Referring now to FIG. 4, exemplary metal bond abrasive wheel 400 has arcuate and cooling channels 420. Similarly, exemplary metal bond abrasive wheel 500 (shown in FIG. 5) has tortuous cooling channels 520.

SELECT EMBODIMENTS OF THE PRESENT DISCLOSURE

In a first embodiment, the present disclosure provides a method of making a metal bond abrasive article, the method comprising the sequential steps:

a) a subprocess comprising sequentially:

i) depositing a layer of loose powder particles in a confined region, wherein the layer of loose powder particles comprises metal particles and abrasive particles, and wherein the layer of loose powder particles has substantially uniform thickness;

ii) jetting a liquid binder precursor material onto at least one predetermined region of the layer of loose powder particles;

b) independently carrying out step a) a plurality of times to generate an abrasive preform comprising the layer of bonded powder particles, wherein the abrasive preform comprises at least one opening extending into the abrasive preform;

d) inserting a mounting member at least partially into the opening;

e) sintering at least a portion of the metal particles in the abrasive preform while the mounting

member is at least partially inserted in the opening to form the metal bond abrasive article. In a second embodiment, the present disclosure provides a method according to the first embodiment, wherein the mounting member is securely affixed in the metal bond abrasive article after step e) is finished.

In a third embodiment, the present disclosure provides a method according to the first or second embodiment, wherein the volume of the abrasive preform shrinks by at least 25 percent in step e).

In a fourth embodiment, the present disclosure provides a method according to any one of first to third embodiments, wherein in each step a), the loose powder particles are independently selected, and the liquid binder precursor material is independently selected.

In a fifth embodiment, the present disclosure provides a method according to any one of first to fourth embodiments, wherein the abrasive particles comprise at least one of diamond particles or cubic boron nitride particles.

In a sixth embodiment, the present disclosure provides a method according to any one of first to fifth embodiments, wherein the abrasive particles comprise metal oxide ceramic particles.

In a seventh embodiment, the present disclosure provides a method according to any one of first to sixth embodiments, wherein the metal bond abrasive article includes at least one cooling channel.

In an eighth embodiment, the present disclosure provides a method according to any one of first to seventh embodiments, wherein the metal bond abrasive article comprises an abrasive grinding bit or an abrasive wheel.

In a ninth embodiment, the present disclosure provides a method according to any one of first to seventh embodiments, wherein the metal bond abrasive article comprises at least a portion of a rotary dental tool.

In a tenth embodiment, the present disclosure provides a method according to any one of first to ninth embodiments, wherein the liquid binder precursor material comprises a liquid vehicle having a polymer dissolved therein.

In an eleventh embodiment, the present disclosure provides a method according to the tenth embodiment, wherein the liquid vehicle predominantly comprises water.

In a twelfth embodiment, the present disclosure provides a method according to any one of first to eleventh embodiments, further comprising, between steps c) and d), burning off at least a portion of the binder material.

In a thirteenth embodiment, the present disclosure provides a method according to any one of first to twelfth embodiments, wherein the loose powder particles further comprise fluxing agent particles.

In a fourteenth embodiment, the present disclosure provides a metal bond abrasive article made according to a method of any one of the first embodiment to the thirteenth embodiment.

In a fifteenth embodiment, the present disclosure provides a metal bond abrasive article comprising:

an abrasive member comprising a metal matrix containing abrasive particles; and a mounting member, wherein the mounting member extends into, and is directly fused to, the abrasive member.

In a sixteenth embodiment, the present disclosure provides a metal bond abrasive article according to the fifteenth embodiment, wherein the abrasive particles comprise at least one of diamond particles or cubic boron nitride particles.

In a seventeenth embodiment, the present disclosure provides a metal bond abrasive article according to the fifteenth or sixteenth embodiment, wherein the abrasive particles comprise metal oxide ceramic particles.

In an eighteenth embodiment, the present disclosure provides a metal bond abrasive article according to any one of the fifteenth to seventeenth embodiments, wherein the metal bond abrasive article includes at least one cooling channel.

In a nineteenth embodiment, the present disclosure provides a metal bond abrasive article according to any one of the fifteenth to eighteenth embodiments, wherein the metal bond abrasive article comprises an abrasive grinding bit or an abrasive wheel.

In a twentieth embodiment, the present disclosure provides a metal bond abrasive article according to any one of the fifteenth to eighteenth embodiments, wherein the metal bond abrasive article comprises at least a portion of a rotary dental tool.

Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. In the Examples: °C = degrees Celsius, g = grams, min = minute, mm = millimeter, sec = second, and rpm = revolutions per minute.

General 3-D Part Manufacturing Procedure :

A mixture of metal powder(s) and diamonds was prepared and placed into the feed chamber of an ExOne M-lab printer (ExOne Company, North Huntingdon, Pennsylvania). A 3D model was prepared as a computer file to make a part for a metal bond abrasive tool. The ExOne M-lab printer repeatedly spread the powder mixture as a layer, jetted binder in a 2D pattern made from successive cross-sections of the 3D object. The binder was at least partially dried between jetting and powder spreading steps. After completion, the result was a powder bed holding loose powder and 3D shapes of binder and powder. That powder bed was removed from the printer and baked in an oven. After cooling, those 3D shapes or “green” parts were extracted and depowdered. A metal shaft was inserted into the“green” parts before placing the assembly into the furnace. The green parts were placed into a furnace to bum out the binder and then melt and sinter at least some of the metal. The resulting at least partially sintered parts had increased strength and had density changes relative to the green part used, where the profile consists of temperatures and times while the parts were in the furnace. The fired parts were evaluated against a variety of materials to assess abrasive performance.

EXAMPLE 1

A powder mixture of 25% cobalt, 75% bronze (composed of copper and tin in amounts of 87% and 13%, respectively) was prepared. Diamonds of sizes 12-22 microns were added in amount 6.6% by weight to the metal powder mixture. The binder material was ExOne PM-B-SR1-04. Key settings for the ExOne M-Lab printer were binder saturation of 70%, spread speed of 1 mm/s, and 30 second drying time with heater setting at 90% between each layer of 100 micron thickness. The General 3-D Part

Manufacturing Procedure was carried out using a part shape of a 6.0 mm long tube having an 8.00 mm outer diameter and a 3.00 mm diameter central bore hole that extended the length of the tube. The powder bed containing loose powder and the green body of bound powder was placed in an oven for four hours at 195 °C. After cooling back to room temperature, the parts were extracted from the powder bed and the loose powder was removed. A steel set screw with diameter 2.8 mm was inserted part way into the central bore hole. These parts were placed into a furnace for the time and temperature profile of: ramp from room temperature to 450 °C at rate about 3 degrees per minute, hold at 450 °C for 60 minutes, ramp to 850 °C at rates about 3 degrees per minute, hold at 850 °C for 60 minutes and ramp back down to room temperature about 3 degrees per minute.

The tool shown above was used to edge grind a piece of Gorilla Glass 5 (Coming Glass, Coming, New York). The testing of the glass was done on a Haas CM-1 high speed CNC milling machine (Haas Automation Inc., Oxnard, California). The piece of glass is 0.7 mm thick x 75mm x 155 mm. The tool path was designed to create round the comers of the glass on the first pass with a depth of cut of 300 microns ( 0.3 mm). The rotation rate of the tool was 50,000 RPM. The feed rate on the straight sides is 559 mm/min and 279 mm/min on the comer grind. A second grind or fine grind then done at a slightly lower depth of cut of 200 microns ( 0.2 mm). The straight side feed rate was 657 mm/min and 411 mm/min on the comer grind. The resulting glass part had the correct edge profile with no edge chips. The grinding tool was used to create multiple glass parts in order to evaluate the wear of the tool and consistency of the edge profile on the glass. After grinding 20 glass parts there was no loosening of the sintered metal bond part from the shaft.

EXAMPLE 2

A powder mixture of 25% cobalt, 75% bronze (composed of copper and tin in amounts of 87% and 13%, respectively) was prepared. Diamonds of sizes 12-22 microns were added in amount 6.6% by weight to the metal powder mixture. The binder material was ExOne PM-B-SR1-04. Key settings for the ExOne M-Lab printer were binder saturation of 70%, spread speed of 1 mm/s, and 30 second drying time with heater setting at 90% between each layer of 100 micron thickness. The General 3-D Part Manufacturing Procedure was carried out to provide a 5.50 mm high, 4 mm diameter cylinder having a 2.00 mm diameter central bore hole that extended 3.5 mm into the end of the cylinder. The powder bed containing loose powder and 3D shapes of bound powder was placed in an oven for four hours at 195 °C. After cooling back to room temperature, the parts were extracted from the powder bed and the loose powder was removed. The parts shown had 2.0 mm holes within the body, and a smooth steel shaft having an end diameter of 1.5 mm was inserted into the hole. These parts were placed into a furnace for the time and temperature profile of: ramp from room temperature to 450 °C at rate about 3 degrees per minute, hold at 450 °C for 60 minutes, ramp to 850 °C at rates about 3 degrees per minute, hold at 850 °C for 60 minutes and ramp back down to room temperature about 3 degrees per minute. After the processing in the furnace, the parts were tightly attached to the smooth shafts.

All cited references, patents, and patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.

Claims

What is claimed is:

1. A method of making a metal bond abrasive article, the method comprising the sequential steps:

a) a subprocess comprising sequentially:

c) separating substantially all of any loose powder particles from the abrasive preform; d) inserting a mounting member at least partially into the opening;

e) sintering at least a portion of the metal particles in the abrasive preform while the

mounting member is at least partially inserted in the opening to form the metal bond abrasive article.

2. The method of claim 1, wherein the mounting member is securely affixed in the metal bond abrasive article after step e) is finished.

3. The method of claim 1 or claim 2, wherein the volume of the abrasive preform shrinks by at least 25 percent in step e).

4. The method of any one of claims 1 to 3, wherein in each step a), the loose powder particles are independently selected, and the liquid binder precursor material is independently selected.

5. The method of any one of claims 1 to 4, wherein the abrasive particles comprise at least one of diamond particles or cubic boron nitride particles.

6. The method of any one of claims 1 to 5, wherein the abrasive particles comprise metal oxide ceramic particles.

7. The method of any one of claims 1 to 6, wherein the metal bond abrasive article includes at least one cooling channel.

8. The method of any one of claims 1 to 7, wherein the metal bond abrasive article comprises an abrasive grinding bit or an abrasive wheel.

9. The method of any one of claims 1 to 7, wherein the metal bond abrasive article comprises at least a portion of a rotary dental tool.

10. The method of any one of claims 1 to 9, wherein the liquid binder precursor material comprises a liquid vehicle having a polymer dissolved therein.

11. The method of claim 10, wherein the liquid vehicle predominantly comprises water.

12. The method of any one of claims 1 to 11, further comprising, between steps c) and d), burning off at least a portion of the binder material.

13. The method of any one of claims 1 to 12, wherein the loose powder particles further comprise fluxing agent particles.

14. A metal bond abrasive article made according to the method of any one of claims 1 to 13.

15. A metal bond abrasive article comprising:

16. The metal bond abrasive article of claim 15, wherein the abrasive particles comprise at least one of diamond particles or cubic boron nitride particles.

17. The metal bond abrasive article of claim 15 or claim 16, wherein the abrasive particles comprise metal oxide ceramic particles.

18. The metal bond abrasive article of any one of claims 15 to 17, wherein the metal bond abrasive article includes at least one cooling channel.

19. The metal bond abrasive article of any one of claims 15 to 18, wherein the metal bond abrasive article comprises an abrasive grinding bit or an abrasive wheel.

20. The metal bond abrasive article of any one of claims 15 to 18, wherein the metal bond abrasive article comprises at least a portion of a rotary dental tool.