DESC:TECHNICAL FIELD
[1] The present disclosure relates generally to the field of additive manufacturing. In particular, the present disclosure relates to preparation of stock powders for use in an additive manufacturing process.

BACKGROUND
[2] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[3] Metal powders are widely used, among other applications, as material for additive manufacturing processes, and other manufacturing techniques to produce metal components and systems either of pure metals or of metal alloys. The particle size of most metal powders in such applications vary from greater than about 10 micrometers to about 250 micrometers.
[4] Different manufacturing methods such as atomization and electrolytic precipitation are widely used for production of a variety of metal powders. The manufacturing processes are adapted to obtain metal powders of desired physical and chemical characteristics. The main characteristics that describe metal powders include the morphology, size distribution, surface area, and the surface topography. Most commercially available metal powders today are generated by an atomization process – either water, plasma, or a gas atomization. These processes have inherent limitations such as being highly inflexible with respect to material systems, melt temperature limitations, low productivity, large particle size distribution per manufacturing cycle, restricted form of the feedstock. They are also inherently energy and capital intensive leading to high cost of resulting powders. Furthermore, it is also challenging to consistently obtain monodispersed spherically shaped powder particles with high turnover efficiency with respect to the manufacturing cycle time. This results in poor powder yield per manufacturing cycle time and high costs owing to multiple processing cycles.
[5] There is, therefore, a requirement in the art for a means to effectively and efficiently produce stock powders for additive manufacturing and closely allied processes.

OBJECTS OF INVENTION
[6] An object of the present invention is to provide an apparatus for producing stock powders for use in an additive manufacturing or a closely allied process.
[7] Another object of the present invention is to provide an apparatus for producing highly monodispersed stock powder for use in an additive manufacturing process.
[8] Another object of the present invention is to provide an apparatus that can produce stock powders from several different types of bulk materials.
[9] Another object of the present invention is to provide an apparatus with high throughput that is capable of being scaled up for large scale stock powder production.
[10] Another object of the present invention is to provide a method for producing stock powders, post standard oxide reduction treatments, for use in an additive manufacturing or a closely allied process.

SUMMARY
[11] The present disclosure relates generally to the field of additive manufacturing. In particular, the present disclosure relates to preparation of stock powders for use in an additive manufacturing process.
[12] In a first aspect, the present disclosure provides an apparatus for producing a stock powder for an additive manufacturing process. The apparatus includes a bed configured to receive and removably secure a workpiece. The workpiece includes a bulk material to be converted to the stock powder for the additive manufacturing process. The apparatus further includes a grinding wheel configured proximate the bed. The grinding wheel includes an abrasive surface adapted to abrade the workpiece. The grinding wheel is configured to be selectively in contact with the workpiece enabling a relative motion between the abrasive surface of the grinding wheel and a surface of the workpiece. Responsive to bringing the grinding wheel in contact with the surface of the workpiece, the grinding wheel abrades the workpiece to generate particles of a material of the workpiece. The generated particles of the material of the workpiece includes the stock powder for the additive manufacturing process.
[13] In some embodiments, the bed is disposed along a first axis, and the grinding wheel is disposed along a second axis orthogonal to the first axis, such that, when the grinding wheel is in contact with the surface of the workpiece, at a point of contact of the grinding wheel and the surface of the workpiece, the grinding wheel is moving along the first axis.
[14] In some embodiments, the bed is configured to move linearly along the first axis, with respect to a position of the grinding wheel.
[15] In some embodiments, the bed is disposed along a first axis, and the grinding wheel is disposed along a second axis parallel to the first axis, such that, when the grinding wheel is in contact with the surface of the workpiece, at a point of contact of the grinding wheel and the surface of the workpiece, the grinding wheel is moving orthogonal to the first axis.
[16] In some embodiments, the bed is configured to rotate about the first axis.
[17] In some embodiments, the workpiece is secured to the bed by means of a plurality of clamps.
[18] In some embodiments, the apparatus further includes one or more beds, each of the one or more beds configured to receive and removably secure a workpiece. The apparatus further includes one or more grinding wheels configured proximate the one or more beds, such that at least one grinding wheel of the one or more grinding wheels is configured to be selectively in contact with each workpiece in such a way that the abrasive surface of the at least one grinding wheel and a surface of each of the workpieces are in relative motion.
[19] In some embodiments, the apparatus further includes a collection bin configured to receive and store the generated particles of the material of the workpiece.
[20] In some embodiments, the collection bin includes one or more sieves, each of the one or more sieves having one or more sieve sizes. The one or more sieves are adapted to separate the received particles of the material of the workpiece and sort them according to their respective sieve sizes. The sieved particles of the material of the workpiece include the stock powder.
[21] In some embodiments, the stock powder is heated at a predetermined temperature and for a predetermined duration of time in order to reduce a content of moisture in the stock powder.
[22] In some embodiments, the stock powder is heated at a predetermined temperature, for a predetermined duration of time, and under a reducing atmosphere in order to reduce oxide layer in the particles of the stock powder.
[23] In some embodiments, the material of the workpiece includes any one or a combination of metals, and alloys further selected from a group consisting of iron, steel, nickel, titanium, copper, zinc, magnesium, and chromium.
[24] In some embodiments, a material of the abrasive surface of the grinding wheel includes any one or a combination of alumina and cubic boron nitride.
[25] In some embodiments, an atmosphere in which the apparatus is disposed includes any one or a combination of oxygen and inert gases.
[26] In a second aspect, the present disclosure provides a method for producing a stock powder for an additive manufacturing process. The method includes providing a workpiece on a bed configured to receive and removably secure the workpiece. The workpiece includes a bulk material to be converted to the stock powder for the additive manufacturing. The method further includes providing a grinding wheel configured proximate the bed. The grinding wheel includes an abrasive surface adapted to abrade the workpiece. The grinding wheel is configured to be selectively in contact with the workpiece enabling a relative motion between the abrasive surface of the grinding wheel and a surface of the workpiece. The method further includes abrading, by the grinding wheel, responsive to bringing the grinding wheel in contact with the surface of the workpiece, the workpiece to generate particles of a material of the workpiece. The generated particles of the material of the workpiece includes the stock powder for the additive manufacturing process.
[27] In some embodiments, the method further includes providing a collection bin configured to receive and store the generated particles of the material of the workpiece.
[28] In some embodiments, the method further includes providing one or more sieves in the collection bin, each of the one or more sieves having one or more sieve sizes. The method further includes separating, by the one or more sieves, the received particles of the material of the workpiece and sort them according to their respective sieve sizes. The sieved particles of the material of the workpiece include the stock powder.
[29] In some embodiments, the method further includes heating the stock powder at a predetermined temperature and for a predetermined duration of time in order to reduce a content of moisture in the stock powder.
[30] In some embodiments, the method further includes heating the stock powder at a predetermined temperature, for a predetermined duration of time, and under a reducing atmosphere in order to reduce oxide layer in the particles of the stock powder.
[31] In a third aspect, the present disclosure provides a system for performing an additive manufacturing process including the apparatus of the first aspect.
[32] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[33] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[34] FIG. 1 illustrates a schematic view of an apparatus for producing a powder for additive manufacturing, according to an embodiment of the present disclosure;
[35] FIG. 2A illustrates an exemplary scanning electron microscope (SEM) image of a sample of powder produced by the apparatus of FIG. 1;
[36] FIG. 2B illustrates an exemplary SEM image of the sample of powder shown in FIG. 2A, after the powder has been sieved and dried;
[37] FIG. 2C illustrates an exemplary SEM image of a particle of the sample of powder shown in FIG. 2B;
[38] FIG. 2D illustrates an exemplary plot of particle size distribution of the sample of powder shown in FIG. 2B;
[39] FIG. 2E illustrates an exemplary plot depicting a reduction of particles of a sample of powder;
[40] FIG. 3A illustrates a schematic view of an apparatus for producing a stock powder for additive manufacturing, according to another embodiment of the present disclosure;
[41] FIG. 3B illustrates a schematic view of an apparatus for producing a stock powder for additive manufacturing, according to another embodiment of the present disclosure;
[42] FIG. 3C illustrates a schematic view of an apparatus for producing a stock powder for additive manufacturing, according to another embodiment of the present disclosure;
[43] FIG. 4 illustrates a schematic flow diagram for a method for producing stock powder for additive manufacturing process, according to an embodiment of the present disclosure;
[44] FIG. 5A illustrates an exemplary schematic view of an additive manufacturing apparatus;
[45] FIG. 5B illustrates an exemplary SEM image of a deposited track using the apparatus of FIG. 5A;
[46] FIG. 5C illustrates an exemplary optical microscope image of a deposited particle present in the track shown in FIG. 5B;
[47] FIG. 5D illustrates an exemplary energy dispersive X-ray spectroscopy (EDS) of the printed track shown in FIG. 5B;
[48] FIG. 6A illustrates an exemplary optical microscope image depicting a sectional view of the printed track shown in FIG. 5B;
[49] FIG. 6B illustrates an exemplary plot depicting hardness measurements performed on the track shown in FIG. 6A;
[50] FIG. 7A illustrates an exemplary optical microscope image depicting a sectional view of another printed track; and
[51] FIGs. 7B to 7E illustrate exemplary optical microscope images of different sections of the printed track shown in FIG. 7A.

DETAILED DESCRIPTION
[52] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such details as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[53] FIG. 1 illustrates a schematic view of an apparatus 100 for producing a powder for additive manufacturing, according to an embodiment of the present disclosure. The apparatus 100 includes a bed 102. The bed 102 is configured to receive and removably secure a workpiece 104. The workpiece 104 may be mounted on the bed 102. The workpiece 104 is secured in position on the bed 102 using a plurality of clamps 106. The clamps 106 may be physical clamps. Specifically, the clamps 106 may be non-magnetic in nature, in order to avoid magnetizing the workpiece 104. The workpiece 104 includes a bulk material to be converted to the stock powder for the additive manufacturing process. The workpiece 104 may be any metallic or non-metallic material that is required to be powdered in order to be used for the additive manufacturing processes. Some examples of metallic materials which may be used as the workpiece 104 includes, without limitations, high-carbon steels (such as AISI 52100), stainless-steels (such as SS 304), mild steels, nickel-based alloys (such as IN 718, IN 625), titanium-based alloys (such as Ti6Al4V), copper, etc. The workpiece 104 may have any physical attributes, based on requirement of application. Some examples of physical attributes of the workpiece 104 may include, without limitations, size, shape, state of motion, etc.
[54] The apparatus 100 further includes a grinding wheel 108 configured proximate the bed 102. The grinding wheel 108 may be configured so as to be useable for various combinations of grinding parameters, including speed of rotation, and a depth of cut in workpiece during a process of grinding. The grinding wheel 108 may be adapted for surface grinding of the workpiece 104. Specifically, the grinding wheel 108 includes an abrasive surface 110 configured to abrade the surface of the workpiece 104. The abrasive surface 110 forms an outer surface of the grinding wheel 108. Some examples of a material of the abrasive surface 110 of the grinding wheel 108 include, without limitations, alumina, and cubic boron nitride. The grinding wheel 108 may have any material and/or physical attributes, as required for application. Some examples of material and/or physical attributes include, without limitations, diameter, thickness, roughness, abrasive property, material, etc. In some examples, the grinding wheel 108 may have a diameter in a range of between about 150 millimeters (mm) and about 200 mm. Further, in some examples, the grinding parameters may include a speed or rotation in a range of between about 2000 revolutions per minute (RPM) and about 4000 RPM, and a depth of cut in a range of between about 10 micrometers (?m) and about 100 ?m.
[55] The grinding wheel 108 is configured to be selectively in contact with the workpiece 104 enabling a relative motion between the abrasive surface 110 of the grinding wheel 108 and a surface of the workpiece 104. Responsive to bringing the grinding wheel 108 in contact with the surface of the workpiece 104, the grinding wheel 108 abrades the workpiece 104 to generate particles of a material of the workpiece 104. The generated particles of the material of the workpiece 104 include the stock powder for the additive manufacturing process.
[56] In some embodiments, the bed 102 is disposed along a first axis 190, and the grinding wheel 108 is disposed along a second axis 192 orthogonal to the first axis 190, such that, when the grinding wheel 108 is in contact with the surface of the workpiece 104, at a point of contact of the grinding wheel 108 and the surface of the workpiece 104, the grinding wheel 108 is moving along the first axis 190.
[57] In some examples, the workpiece 104 may have a cuboidal shape (such as the workpiece 104 of FIG. 1). Further, in some examples, the workpiece 104 may be stationary. In some other examples, the workpiece 104 may be movable relative to the grinding wheel 108. To effect movement of the workpiece 104, the workpiece 104 may be mounted on a movable bed. In some embodiments, the bed 102 is configured to move linearly along the first axis 190, with respect to a position of the grinding wheel 108. In some embodiments, the bed 102 is an auto-feed bed. In some embodiments the bed 102 may be operated by a computer numerical control (CNC) machine-controlled servo motor (not shown). In some other embodiments, the bed 102 may be operated by a hydraulic mechanism.
[58] As the grinding wheel 108 abrades an outer surface of the workpiece 104, the stock powder of the workpiece material may be obtained. The powder may be collected in a collection bin (not shown in figure) downstream of the grinding process.
[59] The powder may be segregated based on a size of particles of the powder. The powder may be segregated by passing the powders through one or more sieves. Passing the powder through sieves may also allow the oversized, stringy chips of the material of the workpiece 104 to be removed, which may be formed due to the grinding process. In some examples, a sieve with a pore size of less than about 200 ?m may be chosen.
[60] The grinding process atmosphere may be controlled to allow for different configuration of powder particles to be formed. For example, in some cases, the atmosphere may predominantly include inert gases, such as any or a combination of nitrogen, argon, etc., which allows preferential formation of non-spherical particles of the powder. An inert atmosphere forms a reducing atmosphere, and thereby limits oxidation of powders during the grinding process. In some other cases, the atmosphere may include oxygen, which allows formation of spherical particles of the powder. In some other cases, the atmosphere may include a combination of oxygen and one or more inert gases to allow formation of a combination of spherical and non-spherical particles of the powder. In some examples, for spherical powders with a particle size distribution of about 20 ?m, a yield from the apparatus 100 may be about 30%.
[61] The sieved powder may be heated in an oven in order to remove moisture. Removal of moisture from the powders may enable the powder to have a required flowability and may limit agglomeration of particles of the powder. In some examples, the powder may be heated at a temperature range of between about 50 degrees Celsius (?C) and about 75 ?C, for a period of between about 30 minutes and one hour.
[62] FIG. 2A illustrates an exemplary scanning electron microscope (SEM) image 200 of a sample of powder produced by the apparatus 100.
[63] FIG. 2B illustrates an exemplary SEM image 210 of the sample of powder shown in the image 200, after the powder has been sieved and dried.
[64] FIG. 2C illustrates an exemplary SEM image 220 of a particle of the sample of powder shown in the image 210. The particle has a spherical shape, with a diameter of about 30 ?m.
[65] FIG. 2D illustrates an exemplary plot 230 of particle size distribution of the sample of powder shown in the image 210. As can be seen, the particle size varies between about 10 ?m and about 100 ?m. Further, as can be seen, a majority of particles have a size of between about 30 ?m and about 40 ?m.
[66] In some embodiments, oxide content in the powder may be reduced using a suitable reduction treatment. The reduction treatment may include reaction of particles of the powder with a suitable reducing agent, such as hydrogen, ammonia, carbon monoxide, etc. at elevated temperatures.
[67] FIG. 2E illustrates an exemplary plot 240 depicting oxide reduction of particles of a sample of powder. The plot 240 specifically depicts a variation in normalized current ( ) with time ( ) when the particles of the powder are being reduced under a hydrogen atmosphere. The plot 240 further depicts curves 241, 242 corresponding with reduction temperatures of 250 ?C and 350 ?C, respectively. The curves 241 and 242 show an increase in normalized current with increasing time, which may be indicative of a reduction in oxide content in the powder sample, further indicating that any oxide material in the powder sample may be converted to metal. Furthermore, it may be seen that a rate of reduction increases with increase in temperature, as evidenced from the curve 242 which shows increased slope when compared to the curve 241. Thus, it may be surmised that increasing a temperature of reduction process may accelerate the reduction of the particles of the powder.
[68] FIG. 3A illustrates a schematic view of an apparatus 300 for producing a stock powder for additive manufacturing, according to another embodiment of the present disclosure. The apparatus 300 is substantially similar to the apparatus 100 of FIG. 1. Similar components between the apparatus 100 and the apparatus 300 are referenced using the same numeral references. The apparatus 300 includes a grinding wheel 308 having coated abrasives 310.
[69] FIG. 3B illustrates a schematic view of an apparatus 330 for producing a stock powder for additive manufacturing, according to another embodiment of the present disclosure. The apparatus 330 includes one or more apparatuses (such as apparatus 100, apparatus 300, or a combination thereof) arranged to abrade a plurality of workpieces. FIG. 3B illustrates two apparatuses 330-1, 330-2 arranged to abrade two workpieces. Such a setup allows for increasing a throughput of the workpieces that may be simultaneously abraded and therefore increases a quantity of production of the stock powder.
[70] FIG. 3C illustrates a schematic view of an apparatus 360 for producing a stock powder for additive manufacturing, according to another embodiment of the present disclosure. The apparatus 360 includes a workpiece 364 disposed along a first axis 390 and a grinding wheel 368 disposed along a second axis 392 parallel to the first axis 390, such that, when the grinding wheel 368 is in contact with the surface of the workpiece 364, at a point of contact of the grinding wheel 368 and the surface of the workpiece 364, the grinding wheel 368 is moving orthogonal to the first axis 390. Further, in the illustrated embodiment of FIG. 3C, the workpiece 364 has a cylindrical shape.
[71] FIG. 4 illustrates a schematic flow diagram for a method 400 for producing stock powder for additive manufacturing process, according to an embodiment of the present disclosure. At step 402, the method 400 includes providing the workpiece 104 on the bed 102 configured to receive and removably secure the workpiece 104. At step 404, the method 400 further includes providing the grinding wheel 108 configured proximate the bed 102. At step 406, the method 400 further includes abrading, by the grinding wheel 108, responsive to bringing the grinding wheel 108 in contact with the surface of the workpiece 104, the workpiece 104 to generate particles of a material of the workpiece 104. The generated particles of the material of the workpiece 104 include the stock powder for the additive manufacturing process.
[72] In some embodiments, the method 400 further includes providing a collection bin configured to receive and store the generated particles of the material of the workpiece 104.
[73] In some embodiments, the method 400 further includes providing one or more sieves in the collection bin, each of the one or more sieves having one or more sieve sizes. The method 400 further includes separating, by the one or more sieves, the received particles of the material of the workpiece 104 and sort them according to their respective sieve sizes. The sieved particles of the material of the workpiece 104 include the stock powder.
[74] In some embodiments, the method 400 further includes heating the stock powder at the predetermined temperature and for the predetermined duration of time in order to reduce a content of moisture in the stock powder.
[75] In some embodiments, the method 400 further includes heating the stock powder at a predetermined temperature, for a predetermined duration of time, and under a reducing atmosphere in order to reduce oxide layer in the particles of the stock powder.
[76] FIG. 5A illustrates an exemplary schematic view of a powder delivery nozzle in an additive manufacturing apparatus 500. The apparatus 500 may include the apparatus 100, the apparatus 300, the apparatus 330, or the apparatus 360 (not shown in figure). The powder obtained may be loaded into a hopper 502 of the apparatus 500. In the illustrated embodiment of FIG. 5A, the hopper 502 may be a twin hopper. In some other embodiments, the hopper 502 may be a single hopper, or may include more than two hoppers. The hopper 502 may be coupled to a powder nozzle head 504, such that the powder loaded into the hopper 502 may be transferred from the hopper 502 to the powder nozzle head 504. The powder nozzle head 504 may be coupled to the hopper 502 through a four-way distribution manifold. The powder may be delivered to the powder nozzle head 504 via a pressurized carrier gas. The carrier gas may be an inert gas, such as nitrogen, argon, etc. and the carrier gas may be at a pressure, such as at about 3 bar. The powder nozzle head 504 may include four nozzles 506 (two nozzles are shown in figure). The nozzles 506 may be directed towards a substrate 520. The apparatus 500 further includes a laser source 508, such as a fiber laser source. In an example, the laser source 508 may be a 1-kilowatt (kW), 1080 nanometers (nm) laser source. The laser source 508 may be configured to melt the powder being ejected from the nozzles 506 towards the substrate 520. Such a process may be referred to as a directed energy deposition (DED) process, a laser engineered net shaping (LENS) process, or a direct metal deposition (DMD) process.
[77] In some examples, power of the laser source 508 may be about 300 W, with a laser spot size of about 50 ?m, and a flow rate of the powders from the nozzle 506 may be about 18 grams per minute (g/min). The apparatus 500 may be operated to print single layer tracks with a track length of about 30 mm on the substrate 520. The substrate 520 may be steel.
[78] FIG. 5B illustrates an exemplary scanning electron microscopic (SEM) image 540 of a deposited track using the apparatus 500. Specifically, the image 540 depicts a top view of the track. A thickness of the track is uniform and is about 300 ?m. Longitudinal striations seen are a common occurrence using DED processes.
[79] FIG. 5C illustrates an exemplary optical microscope image 550 of a deposited particle present in the track shown in the image 340. It may be seen that the deposited material is metallurgically bonded with the substrate 520 with no internal voids.
[80] FIG. 5D illustrates an exemplary energy dispersive X-ray spectroscopy (EDS) 560 of the printed track shown in image 550. Peak locations in the EDS 560 represent the corresponding atoms, as labelled. The EDS 560 clearly shows that the composition of the material deposited is the same as that used in the powders with little to no trace of atmospheric oxygen. Furthermore, any potential effect of a thin oxide layer on the powder is also not evident in the final track. This spectrum was taken completely inside the track (highlighted dotted box) and shows no trace of oxygen.
[81] FIG. 6A illustrates an exemplary optical microscope image 610 depicting a sectional view of the printed track shown in FIG. 5B. the image 610 further depicts microstructural information of the printed track, and the microstructural image is obtained by metallographic etching. The image 610 shows typical lath martensite structure that is commonly observed in Fe-C alloys. This is the result of a diffusion-less phase transformation that occurs due to high cooling rates in the DED process. Microstructure of the individual sections near the head and base of the track show uniform martensite structure, and uniform bonding between track and substrate, respectively. The micrograph also shows a near triangular heat affected zone of about 1 mm, which is typical of DED processes.
[82] FIG. 6B illustrates an exemplary plot 620 depicting hardness measurements performed on the track. Specifically, the plot 620 depicts micro-Vickers hardness measurements along the track cross-section and into the substrate 520. The hardness is nearly constant within the track itself and decreases sharply outside the heat affected zone. High hardness values within the martensite phase (380-420 HV) again reiterate the fact that the deposited track is practically identical with that produced when using conventional gas atomized powders.
[83] FIG. 7A illustrates an exemplary optical microscope image 710 depicting a sectional view of another printed track. The track depicting in the image 710 is a multi-layered (4-layered) deposition track and is deposited using an infrared (IR) laser.
[84] FIGs. 7B to 7E illustrate exemplary optical microscope images 720, 730, 740, 750, respectively of different sections of the printed track shown in FIG. 7A. Micrography analyses shows martensitic microstructures and columnar and dendritic grains. Further, the images 720 to 750 suggest that that the microstructures seen in the images are similar to those seen on printed tracks by additive manufacturing methods using conventional powders. Thus, the powders manufactured using the proposed apparatus and method may be comparable to conventional powders. Further, a quality of the printed track may be improved by using reduced powders.
[85] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprise” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.
[86] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions, or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF INVENTION
[87] The present invention provides an apparatus for producing stock powders for use in an additive manufacturing process.
[88] The present invention provides an apparatus for producing highly monodispersed stock powder for use in an additive manufacturing process.
[89] The present invention provides an apparatus that can produce stock powders from several different types of bulk materials.
[90] The present invention provides an apparatus with high throughput that is capable of being scaled up for large scale stock powder production.
[91] The present invention provides a method for producing stock powders for use in an additive manufacturing or a closely allied process.
[92] The present invention provides a method for inexpensive and energy efficient production of stock powders for use in an additive manufacturing or a closely allied process post a standard oxide reduction treatment.
[93] The present invention provides a method for production of stock powders that are of ready-to-print quality for use in an additive manufacturing or a closely allied process.

,CLAIMS:1. An apparatus for producing a stock powder for an additive manufacturing process, the apparatus comprising:
a bed configured to receive and removably secure a workpiece, wherein the workpiece comprises a bulk material to be converted to the stock powder for the additive manufacturing process; and
a grinding wheel configured proximate the bed, the grinding wheel comprising an abrasive surface adapted to abrade the workpiece, wherein the grinding wheel is configured to be selectively in contact with the workpiece enabling a relative motion between the abrasive surface of the grinding wheel and a surface of the workpiece,
wherein, responsive to bringing the grinding wheel in contact with the surface of the workpiece, the grinding wheel abrades the workpiece to generate particles of a material of the workpiece, and
wherein the generated particles of the material of the workpiece comprise the stock powder for the additive manufacturing process.
2. The apparatus as claimed in claim 1, wherein the bed is disposed along a first axis, and the grinding wheel is disposed along a second axis orthogonal to the first axis, such that, when the grinding wheel is in contact with the surface of the workpiece, at a point of contact of the grinding wheel and the surface of the workpiece, the grinding wheel is moving along the first axis.
3. The apparatus as claimed in claim 2, wherein the bed is configured to move linearly along the first axis with respect to a position of the grinding wheel.
4. The apparatus as claimed in claim 1, wherein the bed is disposed along a first axis, and the grinding wheel is disposed along a second axis parallel to the first axis, such that, when the grinding wheel is in contact with the surface of the workpiece, at a point of contact of the grinding wheel and the surface of the workpiece, the grinding wheel is moving orthogonal to the first axis.
5. The apparatus as claimed in claim 4, wherein the bed is configured to rotate about the first axis.
6. The apparatus as claimed in claim 1, wherein the workpiece is secured to the bed by means of a plurality of clamps.
7. The apparatus as claimed in claim 1, further comprising:
one or more beds, each of the one or more beds configured to receive and removably secure a workpiece; and
one or more grinding wheels configured proximate the one or more beds, such that at least one grinding wheel of the one or more grinding wheels is configured to be selectively in contact with each workpiece in such a way that the abrasive surface of the at least one grinding wheel and a surface of each of the workpieces are in relative motion.
8. The apparatus as claimed in claim 1, further comprising a collection bin configured to receive and store the generated particles of the material of the workpiece.
9. The apparatus as claimed in claim 7, wherein the collection bin comprises one or more sieves, each of the one or more sieves having one or more sieve sizes, wherein the one or more sieves are adapted to separate the received particles of the material of the workpiece and sort them according to their respective sieve sizes, and wherein the sieved particles of the material of the workpiece comprise the stock powder.
10. The apparatus as claimed in claim 1, wherein the stock powder is heated at a predetermined temperature and for a predetermined duration of time in order to reduce a content of moisture in the stock powder.
11. The apparatus as claimed in claim 1, wherein the stock powder is heated at a predetermined temperature, for a predetermined duration of time, and under a reducing atmosphere in order to reduce oxide layer in the particles of the stock powder.
12. The apparatus as claimed in claim 1, wherein the material of the workpiece comprises any one or a combination of metals and alloys further selected from a group consisting of iron, steel, nickel, titanium, copper, zinc, magnesium, and chromium.
13. The apparatus as claimed in claim 1, wherein a material of the abrasive surface of the grinding wheel comprises any one or a combination of alumina and cubic boron nitride.
14. The apparatus as claimed in claim 1, wherein an atmosphere in which the apparatus is disposed comprises any one or a combination of oxygen and inert gases.
15. A method for producing a stock powder for an additive manufacturing process, the method comprising:
providing a workpiece on a bed configured to receive and removably secure the workpiece, wherein the workpiece comprises a bulk material to be converted to the stock powder for the additive manufacturing process;
providing a grinding wheel configured proximate the bed, the grinding wheel comprising an abrasive surface adapted to abrade the workpiece, wherein the grinding wheel is configured to be selectively in contact with the workpiece enabling a relative motion between the abrasive surface of the grinding wheel and a surface of the workpiece; and
abrading, by the grinding wheel, responsive to bringing the grinding wheel in contact with the surface of the workpiece, the workpiece to generate particles of a material of the workpiece,
wherein the generated particles of the material of the workpiece comprise the stock powder for the additive manufacturing process.
16. The method as claimed in claim 15, further comprising providing a collection bin configured to receive and store the generated particles of the material of the workpiece.
17. The method as claimed in claim 16, further comprising:
providing one or more sieves in the collection bin, each of the one or more sieves having one or more sieve sizes; and
separating, by the one or more sieves, the received particles of the material of the workpiece and sort them according to their respective sieve sizes, wherein the sieved particles of the material of the workpiece comprise the stock powder.
18. The method as claimed in claim 15, further comprising heating the stock powder at a predetermined temperature and for a predetermined duration of time in order to reduce a content of moisture in the stock powder.
19. The method as claimed in claim 15, further comprising heating the stock powder at a predetermined temperature, for a predetermined duration of time, and under a reducing atmosphere in order to reduce oxide layer in the particles of the stock powder.
20. A system for performing an additive manufacturing process comprising the apparatus of claim 1.