SE2150435A1 - Method and apparatus for additive manufacturing - Google Patents

Abstract

The present invention relates to a method and apparatus for forming a three-dimensional metal component comprising the steps of: depositing onto a substrate provided on a stage at least one green layer, which layer corresponding to a slice of a model of said three-dimensional component, wherein said green layer comprising metal particles in a binder composition, debinding said at least one green layer for forming a brown layer by impinging a laser beam from a laser source having a first setting onto a top surface of said green layer provided on said substrate on said stage, wherein said debinding is removing most of said binder composition, sintering the brown layer by impinging a laser beam from a laser source having second setting onto a top surface of said brown layer, repeating step a-c until the three-dimensional metal component is finished.

Description

METHOD AND APPARATUS FOR ADDITIVE MANUFACTURING Technical field of the lnvention The present invention relates in general to the field of additive manufacturing. ln particular, the present invention relates to a method and apparatus for forming three-dimensional components from a feedstock comprising metal powder and binder composition.

Background of the lnvention Powder bed fusion (PBF) and Bound Metal Deposition (BMD) are two of the most important processes in additive manufacturing of metallic components. The PBF is categorized as a direct manufacturing process due to its process design where a metallic component can be printed in single stage. The BMD on the other hand is classified as an indirect process due to three stages- green body printing, de-binding and sintering- involved in reaching to final printed component. While a PBF process uses metallic powders as raw materials to the process, the raw material in case of an BMD process comprises rods, wires or filaments where metal powder particles are held together by a binding polymer and vax also known as metal-polymer composite. With all the respective advantages in metal component manufacturing, the two processes have critical limitations and disadvantages. ln PBF processes metal powders are complicated in handling due to risk of mixing with other powders. ln PBF it is very difficult to perform multi-material printing. PBF require very large quantities of powder, this is most often the case even for small component or batch sizes. PBF are prone to quality degradation in recycling of a large proportion of the unused powder. ln the BMD process the final shape of the printed component/s requires multiple steps making the process chain complex and demanding. ln BMD de-binding process is intensive in using time (as long as 1-2 days) and various non environmental friendly chemicals may be needed. ln BMD the sintering process is both energy and time intensive with sintering furnace usually held on near-melting temperature of the subject metal/alloy for as long as 1 day. The sintering in this case is a volumetric heating process where whole volume of a printed component is subject to same temperature at any point in time. ln BMD the volumetric fusion in sintering produces volumetric shrinkage in the printed components which can be as high as 30% and therefore makes the design of components challenging.

Today the highest demand is to produce three-dimensional component of the high shape complexity, reduced weight, and localized material features.

P30903 2 There is a need in the art for additive manufacturing method of improved dimension predictability compared to known production methods.

Object of the lnvention The present invention aims at obviating the aforementioned problem. A primary object of the present invention is to provide an improved method for forming a three-dimensional components.

Another object of the invention is to provide a pattern generator configured for patterning a three-dimensional component.

Summary of the lnvention According to the invention at least the primary object is attained by means of the system having the features defined in the independent c|aims.

Preferred embodiments of the present invention are further defined in the dependent c|aims.

According to a first aspect of the present invention it is provided a method for forming a three-dimensional metal component comprising the steps of: a. depositing onto a substrate provided on a stage at least one green layer, which layer corresponding to a slice of a model of said three-dimensional component, wherein said green layer comprising metal particles in a binder composition, b. debinding said at least one green layer for forming a brown layer by impinging a laser beam from a laser source having a first setting onto a top surface of said green layer provided on said substrate on said stage, wherein said debinding is removing most of said binder composition in said green layer, c. sintering the brown layer by impinging a laser beam from a laser source having second setting onto a top surface of said brown layer, d. repeating step a-c until the three-dimensional metal component is finished.

The advantage of this embodiment is that the dimensional deviation from nominal design is minimal. Another advantage is that the method can be applied for different scales (from small to big objects), preserving high accuracy and repeatability of the manufactured three-dimensional metal components. Still another advantage is that it provides for the ability to execute both steps- debinding and sintering/melting- simultaneously and /or in single setup, not only solves several technical challenges but also enhances processing capability and flexibility. Still more advantages P30903 3 are a single stage, high speed additive manufacturing process of metallic components with flexibility of using multiple metallic materials, allow for printing from very small to very large size components without needing large volumes of excess metal powders, building new geometric features on preformed or manufactured components of small or large sizes, avoid volumetric shrinkage due to in-situ sintering/melting layer by layer or batches of layers, thus producing components with better geometric accuracy and near zero porosity, make the sintering process control localized, with sintering spot to be as small as the spot-size of the energy beam, to allow for fine control of temperature, microstructure, and therefore of mechanical properties, allow control of temperature at microscale and flexibility of using dissimilar metals, offering the potential of manufacturing smart components such as components with built-in sensing and actuafingcapabüüy ln various example embodiments according to the present invention said first setting of a laser source is different to said second setting of a laser source by at least one of power, flequencW\Navdengthand/orspotáze The advantage of these embodiments is that the efficiency and controllability of the debinding and/or sintering/melting may be improved. ln various example embodiments according to the present invention said binder composition is wax and/or polymer based.

The advantage of these embodiments is that the binder composition may be chosen for reducing or eliminating its toxic rest products which may be a health risk during debinding. ln various example embodiments according to the present invention said binder composition is less than 25 vol% of the total content of said green layer.

The advantage of these embodiments is that a minimal amount of binder composition may be needed which in turn may result in a more efficient debinding and minimal shrinkage of the additively manufactured component. ln various example embodiments according to the present invention it further comprising the step of in-situ machining of the generated metal layers for improving the surface finish and/or geonnetncalaccuracy.

The advantage of these embodiments is that a true final three-dimensional component may be a result from an efficient process flow. Another advantage is that a manufacturing foot- print may be greatly reduced. ln various example embodiments according to the present invention the sintering is performed with a laser setting to allow for fine control of temperature, microstructure, and volumetric shrinkage.

P30903 4 The advantage of this embodiment is that the material characteristics of the final three- dimensional component may be tailorized by one and the same laser source. ln various example embodiments according to the present invention a localized selective laser re-melting is performed allowing for improving surface finish, geometric accuracy and/or near-zero porosüy.

The advantage of these embodiments is that not only the settings of the laser source itself may affect the material characteristics of the final product but also the number of process steps chosen with the same and/or different laser settings. ln various example embodiments according to the present invention further comprising the step of controlling laser settings for sintering powders particles and/or brown layers of at æa¶twodWeæntmemlmaæHæs The advantage of these embodiments is that a sandwich structure of a three-dimensional component may be manufactured with tailorized material characteristics. ln various example embodiments of the present invention further comprising the step of manipulating the manufacturing process by using a combination of a multi-axis platforms and robots The advantage of these embodiments is that complicated structures may be nnanufactured. ln various example embodiment of the present invention over 80% of the binder composition is removed in sad debinding step.

The advantage of these embodiments is that the purity of the final three-dimensional component may be enhanced. ln various example embodiment of the present invention said metal particles comprising between 2-10 vol% particles of a size less than 500 nm and the remaining vol% of particles of a skelargerthan500r¶n.

Theadvantageoftheseenfibodünentsßthatthefleflbüüyofthefeedänckand/orthe flommbüüyofdeposüedrnatenalontothesubsuaternaybetaüonzed ln another aspect of the present invention it is provided an apparatus for additive manufacturing for forming a three-dimensional metal component, said apparatus comprising: a. astage, b. an extruder for providing onto a substrate on said stage at least one green layer, which layer corresponding to a slice of a model of said three-dimensional component, wherein said green layer comprising metal particles in a binder composition, P30903 5 c. at least one laser source for debinding said at least one green layer by impinging a laser beam from a laser source having a first setting onto a top surface of said green layer provided on said substrate on said stage, d. at least one laser source for sintering the metal particles by impinging a laser beam from a laser source having second setting onto a top surface of said metal particles on said substrate on said stage, e. a control unit for controlling said at least one laser source for debinding, said at least one laser source for sintering, said stage and said extruder, wherein said control unit is further configured to debind the metal particles and sinter the metal particles in situ as the build-up of the three-dimensional metal component proceeds.

The advantage of this embodiment is that one and the same apparatus may manufacture a final three-dimensional component with a feed stock comprising metal power particles and binder composition. ln various example embodiment of the present invention said at least one laser source for debinding and said at least one laser source for sintering is one and the same laser source.

The advantage of these embodiments is a less expensive apparatus. ln various example embodiments of the present invention wherein said a green layer comprises particles of different metal materials and/or wherein different green layers comprises different powder metal materials.

The advantage of these embodiments is that a sandwich structure of a three-dimensional component may be manufactured with tailorized material characteristics in one and the same apparatus.

Further advantages with and features of the invention will be apparent from the following detailed description of preferred embodiments.

Brief description of the drawings A more complete understanding of the abovementioned and other features and advantages of the present invention will be apparent from the following detailed description of preferred embodiments in conjunction with the appended drawings, wherein: Fig. la-d depict a schematic side view of a first example embodiment of the manufacturing of a three-dimensional component according to a method of the present invention.

P30903 6 Fig. 2a-d depict a schematic side view of a second example embodiment of the manufacturing of a three-dimensional component according to a method of the present invention.

Fig. 3a-d depict a schematic side view of a third example embodiment of the manufacturing of a three-dimensional component according to a method of the present invention.

Fig. 4 depicts a schematic perspective view of an example embodiment of an apparatus according to the present invention.

Fig. 5 depicts a schematic perspective view of providing a green layer onto a substrate.

Fig. 6 depicts a schematic perspective view of debinding a green layer for forming a brown layer.

Fig. 7 depicts a schematic perspective view of sintering/fusing a brown layer for forming a fused layer of the three-dimensional component.

Detailed description of preferred embodiments of the invention The process invention here refers to a new Additive Manufacturing (AM) process where using a digital model, a component geometry is built by fusing metal-polymer composite rods/wires/filaments and sintered/melted layer by layer or in batches of layers using an energy source such as a laser beam through either selective sintering/melting or simple scanning of the printed profile, following the fusion process.

This invention is about a direct manufacturing process by integrating the debinding and sintering/melting steps with the printing process. This means, that the new process will be able to manufacture fully or near-fully dense metal components using metal-polymer composite rods/wires/filaments and will overcome all the shortcomings of the two majors, Powder Bed Fusion (PBF) and BMD, process categories.

The new process will enable direct manufacturing characteristic of PBF but without requiring loose powder materials and thus avoiding all handling complexities, safety and health risks associated with the use of powder materials. The new process may also give flexibility to manipulate printing process in more than three axes through by use of a five-axis kinematic and/or combination of a multi-axis platform and robot and also allow improving surface finish (surface roughness) by using localized re-melting capabilities of the selective laser sintering/melting approach.

Figure 4 depicts a schematic perspective view of an example embodiment of an additive manufacturing apparatus 400 according to the present invention which is configured to manufacture three-dimensional components 480. Said apparatus 400 comprises a stage 410 and a P30903 7 printing head 440 provided on a support structure 425 above said stage 410. Said printing head 440 comprises at least one extruder 450 and laser beam optics 455. The printing head 440 may be configured to move in an x-y p|ane relative to said stage 410 so that said printing head 440 is covering a predetermined area of said stage 410. Here the stage 410 is moving on rails 460 in y- direction whereas the printing head 440 is moving on rails 420 in x-direction, i.e., the support structure 425 is fixed. Alternatively, the support structure 425 may be movable in y-direction whereas said printing head 440 may be movable in an x-direction on said rails 420, i.e., the stage 410 is fixed. The printing head 440 may be arranged on at least one motorized support 430 movable along said rail 420 in an x-direction. The rails 420 may be provided on said support structure 425 for guiding of said printing head in said x-direction by means of said motorized support 430. The stage 410 may be fixed or movable in x and/or y direction. A control unit may control the relative movement of said printing head 440 with respect to said stage 410. Said control unit may also control the laser beam optics 455 and the extruder 450. The stage and/or the printing head may also be movable in Z-direction in order to allow for additively manufacture the three-dimensional component and keeping a distance between the extruder 450 and a top surface of the component to which a new layer is to be attached at a constant distance, i.e., for every new applied layer the stage 410 may be moved downwards in Z-direction with a distance corresponding to the thickness of new applied layer or the printing head 440 may be moved upwards in Z-direction with a distance corresponding to the thickness of new applied layer or a combination of movement of said stage downwards in Z-direction and said printing head upwards in Z-direction in order to keep a distance between the extruder 450 and a top surface of the component to which a new layer is to be attached at a constant distance.

Figure 1a-d depict a schematic side view of a first example embodiment of the manufacturing of a three-dimensional component according to a method of the present invention. ln figure 1a the extruder 450 is providing feedstock material 110 onto a substrate 130 for forming a first green layer 120. The substrate 130 may be fixed onto said stage 410 in the additive manufacturing apparatus 400. The substrate may be made of any material, e.g., the same material as the final three-dimensional component, ceramic material or any other metallic material which is different to the material in the three-dimensional component. The first step is the fusion and deposition of metal-polymer composite rods/wires/filaments. The extruder 450 locally deposits the feedstock material along a predefined path. The extruder heats the binder composition, which may be a polymer in the feedstock material and feeds the paste-like raw material through a high precision, wear-resistant nozzle. The nozzle diameter may be from 0.1mm-10mm in diameter. A three-axes kinematic positions the extruder 450 in the machine's work envelope and generates the three- dimensional component 480 layer by layer. The feedstock material 110 may be metal powder P30903 8 particles in a binder composition. Raw feedstock material 110 provided on said substrate 130 is forming a green layer 120 of said three-dimensional component 480. A brown layer 120' may be formed after debinding said binder composition by means of scanning the green layer with a laser beam. A brown layer 120' has no or a very small amont of binder composition left. Laser beam optics 455 may debind and sinter the feedstock material 110 in-situ. The metal particles in the brown layer 120' may be sintered/fused together for forming a metal layer 120"of the three- dimensional component 480. ln figure 1b the extrusion of feedstock material 110 is completed but a first metal layer 120" is to be finalized. Figure 1c-d depict the same procedure as in figure 1a-b but for a second green layer 120 and a second metal layer 120". ln figure 1a-1d only one extruder 450 with a single nozzle is used. ln various example embodiments multiple extruders maybe used in series or in parallel. ln various example embodiments multiple strings of feed stock material 110 may be provided on the substrate 130 simultaneously in order to speed up the green layer 120 formation. During a green layer formation one nozzle for providing feed stock material 110 may be used for a first predetermined layer area of the three-dimensional component and 2 or more nozzles may be used for a second predetermined layer area of the three-dimensional component, i.e., the layer formation may alter between one, two, three or more nozzles depending on the shape of the layer to be formed and/or type of material to be added as green layer. ln various example embodiments a plurality of nozzels for providing feed stock onto the substrate may have the same diameter or different diameter. ln various example embodiments a first extruder 450 may be used for at least a first portion of a first layer for providing a first feed stock material 110 onto the substrate 130. A second extruder may be used for at least a second portion of a second layer for providing a second feed stock material 110' onto said substrate. Said second layer is provided on top of said first layer. Said second feed stock material 110' may have metal particles of another material compared to the metal particles in said first feed stock material 110. ln such way a sandwich formed three- dimensional component may be manufactured having layers of different metal material. ln various example embodiments two or more extruders may be used for a single layer where a first extruder is extruding a first type of feed stock material in a first area of said single layer and a second extruder is extruding a second type of feed stock material in a second area of said single layer. Said first and second feedstock material may have different metal particle material so that a single layer may have at least two areas with different green layer composition. ln order to de-bind and sinter/melt the fused and deposited metal-polymer composite, an energy input in the form of a controllable heat source is required. A laser source with a collimator optic and scanner (light processing unit- LPU) is suitable for this purpose. Two operational modes P30903 9 are possible. A first mode is an in-situ debinding and sintering/melting uses a collimated laser beam in close proximity to the extruder unit which directly debinds and sinters/melts the metal- polymer composite during or shortly after the extrusion which has been descilosed hereinabove in relation to figure la-ld.

A second mode is a layer-by-layer/batch debinding which uses an internal or external laser beam and a light Processing Unit (LPU) to project the collimated laser beam onto the metal- polymer composite surface after the deposition. lt is possible to debind and sinter/melt layer-by- layer or batches of layers.

During the debinding and sintering/melting, the achieved product quality (densification and geometric accuracy) is ensured and corrective measures are initiated in-situ. This includes the possibility to compensate for composite or material imperfections by adjusting the process parameters and/or defect removal by machining. The debinding and sintering/melting requires a specific process environment at the interaction zone of the laser beam and the composite. This is ensured either with the use of a local gas atmosphere (inert gas) or by housing the work envelope in a pressure and temperature-controlled chamber.

The extrusion of the metal-polymer composite is done by the extrusion unit 450. Its functions include the heating of the raw metal-polymer rods/wires/filaments with the purpose to achieve required flowability in material. A feeding mechanism generates a material flow toward a high precision, wear-resistant nozzle. The unit is connected to a storage which supplies the raw metal- polymer rods/wires/filaments/slurry or paste to the extrusion unit. Extruding the metal-polymer composite at temperatures greater than 50 deg. centigrade through a high-precision nozzle depositing thin layer/s as per CAD model of the desired product. The binder composition may be wax or polymer based. The binder composition may be less than 25 vol% of the total content of said green layer. ln various example embodiments said binder composition may be less than 5 vol% of the total content of said green layer. ln various example embodiments said binder composition may be between 1-3 vol% of the total content of said green layer. ln various example embodiments said metal particles in said feed-stock material may comprise between 2-10 vol% particles of a size less than 500 nm and the remaining vol% of particles of a size larger than 500 flm. ln synchronization to extrusion, the functional point is positioned according to a predefined path. This path is derived by slicing the geometry of the workpiece into layers and calculating a time-efficient trajectory for the extrusion of the metal-polymer composite. The positioning is done by a three-axes positioning unit. lt is intended to extend the manufacturing flexibility with a five-axes kinematic in order to further realign the workpiece with reference to the gravity field of earth.

The debinding and sintering/melting process happens sequentially or simultaneously. By applying heat locally, the polymer vaporizes. After reaching a specified temperature, the material starts to sinter/melt. Two options are possible. ln a first option simultaneous processing with a travelling LASER beam, sintering/melting the deposited metal-polymer composite, following in close proximity to the metal-polymer deposition. ln a second option sequential processing with a stationary laser source and an LPU which scans the fused metal-polymer composite surface and selectively sinters/melts either layer-by-layer or batches of layers. Sintering/melting thin layer/s of the metal-polymer composite with high power LASER beam, following the extrusion nozzle to evaporate the polymer content in the layer/s and fuse the metallic particles together to create fully dense metallic artefacts. Alternatively, sintering/melting a thin layer/s of the metal-polymer composite with high power LASER beam through selective laser scanning of the latest printed layer/s, to first evaporate the polymer content in the layer and then to fuse the metallic particles together to create fully dense metallic artefact. Yet another alternative is sintering/melting a batch of thin layers of the deposited metal-polymer composite with high power LASER beam through selective laser scanning of the latest printed layer, where layer by layer scanning is used to first evaporate the polymer content in every single layer and then high intensity laser scanning is used for the batch of layers to fuse the metallic particles together to create fully dense metallic artefact.

The process may require a controlled heat input and timing. To ensure geometric accuracy, in-situ measurements may be made which enable the direct compensation of the process variance. lmperfections in the material may require a quality inspection of the sintered/melted metal layers. ln situ quality control ensuring geometric accuracy, appropriate temperature, and gas content and pressure in the printing environment.

To verify and validate the process capability, the following aspects may require further testing such as evaluation of the achievable metal densification, the debinding and sintering efficiency, the material solidification state after using a laser, fulfilment of minimum geometric accuracy requirements, quantification of material shrinkage from the nominal design, quantification of the achievable layer adhesion and/or ensuring defect-free 3D printing.

Chemical reactions of the metal-polymer composite with the environment may reduce the quality of the sintered/melted layers depending on the metallic powder raw material and bonding polymer. Several measures to control the process environment (temperature, atmosphere, and pressure) are possible to compensate for the process environment variance.

Three-axes positioning unit, metal-polymer composite extruder, collimated laser beam + light processing unit = laser scanner (source: ipgphotonics.com), process environment control chamber.

Figure 2a-2d depict a schematic side view of a second example embodiment of the manufacturing of a three-dimensional component according to a method of the present invention. ln figure 2a the extruder 450 is providing feedstock material 110 onto a substrate 130 for forming a first green layer 120. A partial or full layer may be completed before laser debinding and laser sintering is taking place in figure 2b for forming a metal layer 120". ln figure 2c the extruder 450 is providing feedstock material 110 onto the previous metal layer 120" for forming another green layer 120. ln figure Zd laser debinding and laser sintering is taking place for forming another metal layer 120" of the three-dimensional component. The debinding and sintering may be a single step or a two-step procedure. ln a two-step procedure the debinding may be made of the full green layer area of the three-dimensional component with a first laser setting for forming a brown layer. Thereafter a sintering is made of the full brown layer area with a second laser setting for forming a metal layer of the three-dimensional component. The first laser setting may have less power per unit area and unit time than the second laser setting. The power per unit area and unit time may be varied by changing spot size, dithering frequency, scanning speed, output power of the laser beam and/or changing the number of laser beams.

Figure 3a-3d depict a schematic side view of a third example embodiment of the manufacturing of a three-dimensional component according to a method of the present invention. ln figure 3a the extruder 450 is providing feedstock material 110 onto a substrate 130 for forming a green layer and the laser optics 450 is simultaneous debinding the green layer for forming a first brown layer 120'. ln figure 3b the extruder 450 is providing feedstock material 110 onto said first brown layer for forming a second green layer and the laser optics 450 is simultaneous debinding the second green layer for forming a second brown layer 120'. ln figure 3b we have two brown layers on top of each other. ln figure 3c the two brown layers 120' are sintered for forming a metal layer 120". ln figure 3d a new brown layer 120' is provided on top of the previously formed metal layer which was formed in figure 3c. ln figure 3a-3b it is disclosed forming two brown layers on top of each other before the sintering process is starting. ln various example embodiment more than two brown layer may be formed on top of each other before the sintering step is started, for instance 3,4 or as much as 10 brown layers. The total thickness of brown layers and the metal material in said brown layers is the limiting factor since one or a plurality of laser sources is to be used for the next sintering step which may have a limitation on how thick of a brown layer may be sintered together with a predetermined material characteristics of the produced metal layer.

Figure 5 depicts a schematic perspective view of providing a green layer onto a substrate. Here only a single extruder 450 with a single nozzle is used for applying the green layer for forming the three-dimensional component 480.

Figure 6 depicts a schematic perspective view of debinding a green layer for forming a brown layer. Here a single laser source is used for scanning the top surface of the green layer for forming said brown layer. The heat generated by the laser beam when impinging on said green layer vaporize the binder composition leaving only a small amount of binder composition or no binder composition in the formed brown layer. One or a plurality of laser beams may be used simultaneously for generating the brown layer.

Figure 7 depicts a schematic perspective view of sintering/melting a brown layer for forming a metal layer of the three-dimensional component 480. The heat generated by the laser beam when impinging on said brown layer will melt the metal particles together and forming said metal layer of the three-dimensional component. One or a plurality of laser beam sources may be used simultaneously for transforming said brown layer into said metal layer. The laser setting in the sintering step for forming the metal layer may have more power per unit area and unit time compared to the laser setting for transforming the green layer into a brown layer. ln various example embodiments an in-situ machining of the generated metal layers may be performed for improving the surface finish and/or geometrical accuracy, especially for internal and inaccessible features in a complete additively manufactured component.

Uniqueness of this solution is the innovative combination of metal-polymer fusion with laser sintering / melting. With the ability to execute both steps- fusion and sintering/melting- simultaneously and /or in single setup, not only solves several technical challenges (mentioned above) but also enhances processing capability and flexibility.

The manufacturing method may be used for aviation and space industry (propulsion components, fuel injectors, thrusters, rocket motors, brackets, housing and enclosers, turbines, lightweight components), automotive industry (brackets, steering knuckle, engine parts, cooling system, exhaust system, turbines, housing), bio-medical application (customized medical implants and prosthetics, enhanced medical devices (e.g. surgical tools)), manufacturing (tooling, jigs and fixes, supports), prototyping (functional prototyping), spare parts (on-demand repair can prolongate the use-phase of complex parts with high value). ln principle this new process will be useful in all applications where other metal AM processes are fulfilling the requirements but has the capability and flexibility to perform beyond the limitations of the current processes. All applications mentioned above are of high interest in industry.

Feasible modifications of the lnvention The invention is not limited only to the embodiments described above and shown in the drawings, which primarily have an illustrative and exemplifying purpose. This patent application is intended to cover all adjustments and variants of the preferred embodiments described herein, thus the present invention is defined by the wording of the appended claims and the equivalents thereof. Thus, the equipment may be modified in all kinds of ways within the scope of the appended claims.

Throughout this specification and the claims which follows, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or steps or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (15)

1. An additive manufacturing method for forming a three-dimensional metal component comprising the steps of: a. depositing onto a substrate provided on a stage at least one green layer, which layer corresponding to a slice of a model of said three-dimensional component, wherein said green layer comprising metal particles in a binder composition, b. debinding said at least one green layer for forming a brown layer by impinging a laser beam from a laser source having a first setting onto a top surface of said green layer provided on said substrate on said stage, wherein said debinding is removing most of said binder composition, c. sintering the brown layer by impinging a laser beam from a laser source having second setting onto a top surface of said brown layer, d. repeating step a-c until the three-dimensional metal component is finished.

2. The method according to claim 1, wherein said first setting of a laser source is different to said second setting of a laser source by at least one of power, frequency, wavelength and/or spot size.

3. The method according to any one of claim 1-2, wherein said binder composition is wax or polymer based.

4. The method according to any one of claim 1-3, wherein said binder composition is less than 25 vol% of the total content of said green layer.

5. The method according to any one of claim 1-4, further comprising the step of in-situ machining of the generated metal layers for improving the surface finish and/or geometrical accuracy.

6. The method according to any one of claim 1-5, wherein the sintering is performed with a laser setting to allow for fine control of temperature, microstructure, and volumetric shrinkage. P30903

7. The method according to any one of claim 1-6, wherein a localized selective laser re-melting is performed allowing for improving surface finish, geometric accuracy and/or near-zero porosity.

8. The method according to any one of claim 1-7, further comprising the step of controlling laser settings for sintering powders particles and/or brown layers of at least two different metal materials.

9. The method according to any one of the preceding claims, further comprising the step of manipulating the manufacturing process by using a combination of a multi- axis platforms and robots.

10. The method according to any one ofthe preceding claims, where over 80 % of the binder composition is removed in said debinding step.

11. The method according to any one of the preceding claims, wherein said metal particles comprising between 2-10 vol% particles of a size less than 500 nm and the remaining vol% of particles of a size larger than 500 nm.

12. An additive manufacturing apparatus for forming a three-dimensional metal component, said apparatus comprising: a. a stage, b. an extruder for providing onto a substrate on said stage at least one green layer, which layer corresponding to a slice of a model of said three-dimensional component, wherein said green layer comprising metal particles in a binder composition, c. at least one laser source for debinding said at least one green layer by impinging a laser beam from a laser source having a first setting onto a top surface of said green layer provided on said substrate on said stage, d. at least one laser source for sintering the metal particles by impinging a laser beam from a laser source having second setting onto a top surface of said metal particles on said substrate on said stage, P30903e. a control unit for controlling said at least one laser source for debinding, said at least one laser source for sintering, said stage and said extruder, wherein said control unit is further configured to debind the metal particles and sinter the metal particles in situ as the build-up of the three-dimensional metal component 5 proceeds.

13. The apparatus according to claim 12, wherein said at least one laser source for debinding and said at least one laser source for sintering is one and the same laser source. 10

14. The apparatus according to any one of claim 12-13, further comprising an in-situ multi- axis machining device for machining of the generated metal layers for improving the surface finish or geometrical accuracy.

15. The apparatus according to any one of claim 12-14, wherein said a green layer comprises 15 particles of different metal materials and/or wherein different green layers comprises different powder metal materials.