Patent Publication Number: US-11396135-B2

Title: Powder reclamation and cleaning system for an additive manufacturing machine

Description:
PRIORITY INFORMATION 
     The present applicant claims priority to U.S. Provisional Patent Application Ser. No. 62/584,145 titled “Powder Reclamation and Cleaning System for an Additive Manufacturing Machine” filed on Nov. 10, 2017, the disclosure of which is incorporated by reference herein. 
    
    
     FIELD 
     The present disclosure generally relates to methods and systems adapted to perform additive manufacturing (AM) processes, for example by direct melt laser manufacturing (DMLM), on a larger scale format. 
     BACKGROUND 
     Additive manufacturing (AM) processes generally involve the buildup of one or more materials to make a net or near net shape (NNS) object, in contrast to subtractive manufacturing methods. Though “additive manufacturing” is an industry standard term (ISO/ASTM52900), AM encompasses various manufacturing and prototyping techniques known under a variety of names, including freeform fabrication, 3D printing, rapid prototyping/tooling, etc. AM techniques are capable of fabricating complex components from a wide variety of materials. Generally, a freestanding object can be fabricated from a computer aided design (CAD) model. 
     A particular type of AM process uses an energy source such as an irradiation emission directing device that directs an energy beam, for example, an electron beam or a laser beam, to sinter or melt a powder material, creating a solid three-dimensional object in which particles of the powder material are bonded together. AM processes may use different material systems or additive powders, such as engineering plastics, thermoplastic elastomers, metals, and ceramics. Laser sintering or melting is a notable AM process for rapid fabrication of functional prototypes and tools. Applications include direct manufacturing of complex workpieces, patterns for investment casting, metal molds for injection molding and die casting, and molds and cores for sand casting. Fabrication of prototype objects to enhance communication and testing of concepts during the design cycle are other common usages of AM processes. 
     Selective laser sintering, direct laser sintering, selective laser melting, and direct laser melting are common industry terms used to refer to producing three-dimensional (3D) objects by using a laser beam to sinter or melt a fine powder. More accurately, sintering entails fusing (agglomerating) particles of a powder at a temperature below the melting point of the powder material, whereas melting entails fully melting particles of a powder to form a solid homogeneous mass. The physical processes associated with laser sintering or laser melting include heat transfer to a powder material and then either sintering or melting the powder material. Although the laser sintering and melting processes can be applied to a broad range of powder materials, the scientific and technical aspects of the production route, for example, sintering or melting rate and the effects of processing parameters on the microstructural evolution during the layer manufacturing process have not been well understood. This method of fabrication is accompanied by multiple modes of heat, mass and momentum transfer, and chemical reactions that make the process very complex. 
     During direct metal laser sintering (DMLS) or direct metal laser melting (DMLM), an apparatus builds objects in a layer-by-layer manner by sintering or melting a powder material using an energy beam. The powder to be melted by the energy beam is spread evenly over a powder bed on a build platform, and the energy beam sinters or melts a cross sectional layer of the object being built under control of an irradiation emission directing device. The build platform is lowered and another layer of powder is spread over the powder bed and object being built, followed by successive melting/sintering of the powder. The process is repeated until the part is completely built up from the melted/sintered powder material. 
     After fabrication of the part is complete, various post-processing procedures may be applied to the part. Post processing procedures include removal of excess powder by, for example, blowing or vacuuming. Other post processing procedures include a stress release process. Additionally, thermal and chemical post processing procedures can be used to finish the part. 
     Certain conventional AM machines include a build unit that is supported by an overhead gantry. The gantry defines a build area and facilitates movement of the build unit within the build area to repeatedly deposit layers of powder and fuse portions of each layer to build one or more components. The build unit may further include a powder dispenser which includes a powder reservoir or hopper. The hopper is filled with additive powder which is dispensed layer-by-layer during the AM process. Throughout a typical AM process, the hopper of the powder dispenser must be refilled many times. 
     Notably, the refill process may frequently generate misdirected powder or spillage which can result in operational issues with the machine, imperfections in the finished components, and increased material costs. For example, a refill process typically includes a conveyor that transports additive powder from a reservoir to the hopper where the powder falls off of the conveyor and into the hopper. However, additive powder frequently misses the powder hopper or the hopper may be accidentally overfilled such that additive powder spills over the sides of the hopper. In addition, the collection of falling powder from the conveyor into the hopper may generate a cloud or plume of additive powder which settles throughout the additive manufacturing machine. 
     Accordingly, an AM machine with an improved powder refilling system would be useful. More particularly, a powder refill, reclamation, and cleaning system that reduces the loss of powder during a refill operation and maintains a clean operating environment would be particularly beneficial. 
     BRIEF DESCRIPTION 
     Aspects and advantages will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     According to an exemplary embodiment of the present subject matter, an additive manufacturing machine defining a vertical direction is provided. The additive manufacturing machine includes a build unit including a powder dispenser including a hopper for receiving a volume of additive powder. A powder supply system includes a powder supply source for providing additive powder into the hopper during a refill process. A powder reclamation system includes a vacuum pump for generating a vacuum and a vacuum duct extending from the vacuum pump to a suction inlet, the suction inlet being positioned for collecting misdirected additive powder dispensed during the refill process. 
     These and other features, aspects and advantages will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain certain principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended Figs., in which: 
         FIG. 1  shows a large scale additive manufacturing apparatus according to an embodiment of the invention; 
         FIG. 2  shows a side view of a build unit according to an embodiment of the invention; 
         FIG. 3  shows a side view of a build unit dispensing powder according to an embodiment of the invention; 
         FIG. 4  shows a top view of a build unit according to an embodiment of the invention; 
         FIG. 5  shows a top view of a recoater according to an embodiment of the present invention; 
         FIG. 6  illustrates a large scale additive manufacturing apparatus with two build units according to an embodiment of the present invention; 
         FIG. 7  illustrates a perspective view of a powder supply system according to an embodiment of the present invention; 
         FIG. 8  illustrates a schematic view of a powder supply system and a powder reclamation system according to an embodiment of the present invention; 
         FIG. 9  illustrates a schematic view of a gate cleaning system according to an embodiment of the present invention; and 
         FIG. 10  shows an exemplary control system for use with an additive manufacturing machine and powder refill system according to an embodiment of the invention. 
     
    
    
     Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention. 
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. In addition, the terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. Furthermore, as used herein, terms of approximation, such as “approximately,” “substantially,” or “about,” refer to being within a ten percent margin of error. 
     An additive manufacturing machine is generally provided which includes a build unit comprising a powder dispenser including a hopper for receiving a volume of additive powder. A powder supply system includes a powder supply source for providing additive powder into the hopper during a refill process. A powder reclamation system includes a vacuum pump coupled to a vacuum duct defining a suction inlet positioned for collecting misdirected additive powder dispensed during the refill process. A return duct including a filter mechanism may filter and return the collected additive powder back to the powder supply source for reuse. 
       FIG. 1  shows an example of one embodiment of a large-scale additive manufacturing apparatus  300  according to the present invention. The apparatus  300  comprises a positioning system  301 , a build unit  302  comprising an irradiation emission directing device  303 , a laminar gas flow zone  307 , and a build plate (not shown in this view) beneath an object being built  309 . The maximum build area is defined by the positioning system  301 , instead of by a powder bed as with conventional systems, and the build area for a particular build can be confined to a build envelope  308  that may be dynamically built up along with the object. The gantry  301  has an x crossbeam  304  that moves the build unit  302  in the x direction. There are two z crossbeams  305 A and  305 B that move the build unit  302  and the x crossbeam  304  in the z direction. The x cross beam  304  and the build unit  302  are attached by a mechanism  306  that moves the build unit  302  in the y direction. In this illustration of one embodiment of the invention, the positioning system  301  is a gantry, but the present invention is not limited to using a gantry. In general, the positioning system used in the present invention may be any multidimensional positioning system such as a delta robot, cable robot, robot arm, etc. The irradiation emission directing device  303  may be independently moved inside of the build unit  302  by a second positioning system (not shown). The atmospheric environment outside the build unit, i.e. the “build environment,” or “containment zone,” is typically controlled such that the oxygen content is reduced relative to typical ambient air, and so that the environment is at reduced pressure. 
     There may also be an irradiation source that, in the case of a laser source, originates the photons comprising the laser beam irradiation is directed by the irradiation emission directing device. When the irradiation source is a laser source, then the irradiation emission directing device may be, for example, a galvo scanner, and the laser source may be located outside the build environment. Under these circumstances, the laser irradiation may be transported to the irradiation emission directing device by any suitable means, for example, a fiber-optic cable. According to an exemplary embodiment, irradiation emission directing device uses an optical control unit for directing the laser beam. An optical control unit may comprise, for example, optical lenses, deflectors, mirrors, and/or beam splitters. Advantageously, a telecentric lens may be used. When a large-scale additive manufacturing apparatus according to an embodiment of the present invention is in operation, if the irradiation emission directing devices directs a laser beam, then generally it is advantageous to include a gasflow device providing substantially laminar gas flow to a gasflow zone as illustrated in  FIG. 1, 307  and  FIG. 2, 404 . 
     When the irradiation source is an electron source, then the electron source originates the electrons that comprise the e-beam that is directed by the irradiation emission directing device. An e-beam is a well-known source of irradiation. When the source is an electron source, then it is important to maintain sufficient vacuum in the space through which the e-beam passes. Therefore, for an e-beam, there is no gas flow across the gasflow zone (shown, for example at  FIG. 1, 307 ). When the irradiation source is an electron source, then the irradiation emission directing device may be, for example, an electronic control unit which may comprise, for example, deflector coils, focusing coils, or similar elements. 
     The apparatus  300  allows for a maximum angle of the beam to be a relatively small angle θ 2  to build a large part, because (as illustrated in  FIG. 1 ) the build unit  302  can be moved to a new location to build a new part of the object being formed  309 . When the build unit is stationary, the point on the powder that the energy beam touches when θ 2  is 0 defines the center of a circle in the xy plane (the direction of the beam when θ 2  is approximately 0 defines the z direction), and the most distant point from the center of the circle where the energy beam touches the powder defines a point on the outer perimeter of the circle. This circle defines the beam&#39;s scan area, which may be smaller than the smallest cross sectional area of the object being formed (in the same plane as the beam&#39;s scan area). There is no particular upper limit on the size of the object relative to the beam&#39;s scan area. 
     In some embodiments, the recoater used is a selective recoater. One embodiment is illustrated in  FIGS. 2 through 5 . 
       FIG. 2  shows a build unit  400  comprising an irradiation emission directing device  401 , a gasflow device  403  with a pressurized outlet portion  403 A and a vacuum inlet portion  403 B providing gas flow to a gasflow zone  404 , and a recoater  405 . Above the gasflow zone  404  there is an enclosure  418  containing an inert environment  419 . The recoater  405  has a hopper  406  comprising a back plate  407  and a front plate  408 . The recoater  405  also has at least one actuating element  409 , at least one gate plate  410 , a recoater blade  411 , an actuator  412 , and a recoater arm  413 . The recoater is mounted to a mounting plate  420 .  FIG. 2  also shows a build envelope  414  that may be built by, for example, additive manufacturing or Mig/Tig welding, an object being formed  415 , and powder  416  contained in the hopper  405  used to form the object  415 . In this particular embodiment, the actuator  412  activates the actuating element  409  to pull the gate plate  410  away from the front plate  408 . In an embodiment, the actuator  412  may be, for example, a pneumatic actuator, and the actuating element  409  may be a bidirectional valve. In an embodiment, the actuator  412  may be, for example, a voice coil, and the actuating element  409  may be a spring. There is also a hopper gap  417  between the front plate  408  and the back plate  407  that allows powder to flow when a corresponding gate plate is pulled away from the powder gate by an actuating element. The powder  416 , the back plate  407 , the front plate  408 , and the gate plate  410  may all be the same material. Alternatively, the back plate  407 , the front plate  408 , and the gate plate  410  may all be the same material, and that material may be one that is compatible with the powder material, such as cobalt-chrome. In this particular embodiment, the gas flow in the gasflow zone  404  flows in the y direction, but it does not have to. The recoater blade  411  has a width in the x direction. The direction of the irradiation emission beam when θ 2  is approximately 0 defines the z direction in this view. The gas flow in the gasflow zone  404  may be substantially laminar. The irradiation emission directing device  401  may be independently movable by a second positioning system (not shown).  FIG. 2  shows the gate plate  410  in the closed position. 
       FIG. 3  shows the build unit of  FIG. 2 , with the gate plate  410  in the open position (as shown by element  510 ) and actuating element  509 . Powder in the hopper is deposited to make fresh powder layer  521 , which is smoothed over by the recoater blade  511  to make a substantially even powder layer  522 . In some embodiments, the substantially even powder layer may be irradiated at the same time that the build unit is moving, which would allow for continuous operation of the build unit and thus faster production of the object. 
       FIG. 4  shows a top down view of the build unit of  FIG. 2 . For simplicity, the object and the walls are not shown here. The build unit  600  has an irradiation emission directing device  601 , an attachment plate  602  attached to the gasflow device  603 , hopper  606 , and recoater arm  611 . The gasflow device has a gas outlet portion  603 A and a gas inlet portion  603 B. Within the gasflow device  603  there is a gasflow zone  604 . The gasflow device  603  provides laminar gas flow within the gasflow zone  604 . There is also a recoater  605  with a recoater arm  611 , actuating elements  612 A,  612 B, and  612 C, and gate plates  610 A,  610 B, and  610 C. The recoater  605  also has a hopper  606  with a back plate  607  and front plate  608 . In this particular illustration of one embodiment of the present invention, the hopper is divided into three separate compartments containing three different materials  609 A,  609 B, and  609 C. There are also gas pipes  613 A and  613 B that feed gas out of and into the gasflow device  603 . 
       FIG. 5  shows a top down view of a recoater according to one embodiment, where the recoater has a hopper  700  with only a single compartment containing a powder material  701 . There are three gate plates  702 A,  702 B, and  702 C that are controlled by three actuating elements  703 A,  703 B, and  703 C. There is also a recoater arm  704  and a wall  705 . When the recoater passes over a region that is within the wall, such as indicated by  707 , the corresponding gate plate  702 C may be held open to deposit powder in that region  707 . When the recoater passes over a region that is outside of the wall, such as the region indicated as  708 , the corresponding gate plate  702 C is closed by its corresponding actuating element  703 C, to avoid depositing powder outside the wall, which could potentially waste the powder. Within the wall  705 , the recoater is able to deposit discrete lines of powder, such as indicated by  706 . The recoater blade (not shown in this view) smooths out the powder deposited. 
     Advantageously, a selective recoater according to embodiments of the apparatus and methods described herein allows precise control of powder deposition using powder deposition device (e.g. a hopper) with independently controllable powder gates as illustrated, for example, in  FIG. 4, 606, 610A, 610B, and 610C  and  FIG. 5, 702A, 702B, and 702C . The powder gates are controlled by at least one actuating element which may be, for instance, a bidirectional valve or a spring (as illustrated, for example, in  FIG. 2, 409 . Each powder gate can be opened and closed for particular periods of time, in particular patterns, to finely control the location and quantity of powder deposition (see, for example,  FIG. 4 ). The hopper may contain dividing walls so that it comprises multiple chambers, each chamber corresponding to a powder gate, and each chamber containing a particular powder material (see, for example,  FIG. 4, and 609A, 609B, and 609C ). The powder materials in the separate chambers may be the same, or they may be different. Advantageously, each powder gate can be made relatively small so that control over the powder deposition is as fine as possible. Each powder gate has a width that may be, for example, no greater than about 2 inches, or more preferably no greater than about ¼ inch. In general, the smaller the powder gate, the greater the powder deposition resolution, and there is no particular lower limit on the width of the powder gate. The sum of the widths of all powder gates may be smaller than the largest width of the object, and there is no particular upper limit on the width of the object relative to the sum of the widths of the power gates. Advantageously, a simple on/off powder gate mechanism according to one embodiment is simpler and thus less prone to malfunctioning. It also advantageously permits the powder to come into contact with fewer parts, which reduces the possibility of contamination. Advantageously, a recoater according to an embodiment of the present invention can be used to build a much larger object. For example, the largest xy cross sectional area of the recoater may be smaller than the smallest cross sectional area of the object, and there is no particular upper limit on the size of the object relative to the recoater. Likewise, the width of the recoater blade may smaller than the smallest width of the object, and there is no particular upper limit on the width of the object relative to the recoater blade. After the powder is deposited, a recoater blade can be passed over the powder to create a substantially even layer of powder with a particular thickness, for example about 50 microns, or preferably about 30 microns, or still more preferably about 20 microns. Another feature of some embodiments of the present invention is a force feedback loop. There can be a sensor on the selective recoater that detects the force on the recoater blade. During the manufacturing process, if there is a time when the expected force on the blade does not substantially match the detected force, then control over the powder gates may be modified to compensate for the difference. For instance, if a thick layer of powder is to be provided, but the blade experiences a relatively low force, this scenario may indicate that the powder gates are clogged and thus dispensing powder at a lower rate than normal. Under these circumstances, the powder gates can be opened for a longer period of time to deposit sufficient powder. On the other hand, if the blade experiences a relatively high force, but the layer of powder provided is relatively thin, this may indicate that the powder gates are not being closed properly, even when the actuators are supposed to close them. Under these circumstances, it may be advantageous to pause the build cycle so that the system can be diagnosed and repaired, so that the build may be continued without comprising part quality. Another feature of some embodiments of the present invention is a camera for monitoring the powder layer thickness. Based on the powder layer thickness, the powder gates can be controlled to add more or less powder. 
     In addition, an apparatus according to an embodiment of the present invention may have a controlled low oxygen build environment with two or more gas zones to facilitate a low oxygen environment. The first gas zone is positioned immediately over the work surface. The second gas zone may be positioned above the first gas zone, and may be isolated from the larger build environment by an enclosure. For example, in  FIG. 2  element  404  constitutes the first gas zone, element  419  constitutes the second gas zone contained by the enclosure  418 , and the environment around the entire apparatus is the controlled low oxygen build environment. In the embodiment illustrated in  FIG. 2 , the first gasflow zone  404  is essentially the inner volume of the gasflow device  403 , i.e. the volume defined by the vertical (xz plane) surfaces of the inlet and outlet portions ( 403 A and  403 B), and by extending imaginary surfaces from the respective upper and lower edges of the inlet portion to the upper and lower edges of the outlet portion in the xy plane. When the irradiation emission directing device directs a laser beam, then the gasflow device preferably provides substantially laminar gas flow across the first gas zone. This facilitates removal of the effluent plume caused by laser melting. Accordingly, when a layer of powder is irradiated, smoke, condensates, and other impurities flow into the first gasflow zone, and are transferred away from the powder and the object being formed by the laminar gas flow. The smoke, condensates, and other impurities flow into the low-pressure gas outlet portion and are eventually collected in a filter, such as a HEPA filter. By maintaining laminar flow, the aforementioned smoke, condensates and other impurities can be efficiently removed while also rapidly cooling melt pool(s) created by the laser, without disturbing the powder layer, resulting in higher quality parts with improved metallurgical characteristics. In an aspect, the gas flow in the gasflow volume is at about 3 meters per second. The gas may flow in either the x or y direction. 
     The oxygen content of the second controlled atmospheric environment is generally approximately equal to the oxygen content of the first controlled atmospheric environment, although it doesn&#39;t have to be. The oxygen content of both controlled atmospheric environments is preferably relatively low. For example, it may be 1% or less, or more preferably 0.5% or less, or still more preferably 0.1% or less. The non-oxygen gases may be any suitable gas for the process. For instance, nitrogen obtained by separating ambient air may be a convenient option for some applications. Some applications may use other gases such as helium, neon, or argon. An advantage of the invention is that it is much easier to maintain a low-oxygen environment in the relatively small volume of the first and second controlled atmospheric environments. In prior art systems and methods, the larger environment around the entire apparatus and object must be tightly controlled to have a relatively low oxygen content, for instance 1% or less. This can be time-consuming, expensive, and technically difficult. Thus it is preferable that only relatively smaller volumes require such relatively tight atmospheric control. Therefore, in the present invention, the first and second controlled atmospheric environments may be, for example, 100 times smaller in terms of volume than the build environment. The first gas zone, and likewise the gasflow device, may have a largest xy cross sectional area that is smaller than the smallest cross sectional area of the object. There is no particular upper limit on the size of the object relative to the first gas zone and/or the gasflow device. Advantageously, the irradiation emission beam (illustrated, for example, as  402  and  502 ) fires through the first and second gas zones, which are relatively low oxygen zones. And when the first gas zone is a laminar gasflow zone with substantially laminar gas flow, the irradiation emission beam is a laser beam with a more clear line of sight to the object, due to the aforementioned efficient removal of smoke, condensates, and other contaminants or impurities. 
     One advantage of the present invention is that, in some embodiments, the build plate may be vertically stationary (i.e. in the z direction). This permits the build plate to support as much material as necessary, unlike the prior art methods and systems, which require some mechanism to raise and lower the build plate, thus limiting the amount of material that can be used. Accordingly, the apparatus of the present invention is particularly suited for manufacturing an object within a large (e.g., greater than 1 m 3 ) build envelope. For instance, the build envelope may have a smallest xy cross sectional area greater than 500 mm 2 , or preferably greater than 750 mm 2 , or more preferably greater than 1 m 2 . The size of the build envelope is not particularly limited. For instance, it could have a smallest cross sectional area as large as 100 m 2 . Likewise, the formed object may have a largest xy cross sectional area that is no less than about 500 mm 2 , or preferably no less than about 750 mm 2 , or still more preferably no less than about 1 m 2 . There is no particular upper limit on the size of the object. For example, the object&#39;s smallest xy cross sectional area may be as large as 100 m 2 . Because the build envelope retains unfused powder about the object, it can be made in a way that minimizes unfused powder (which can potentially be wasted powder) within a particular build, which is particularly advantageous for large builds. When building large objects within a dynamically grown build envelope, it may be advantageous to build the envelope using a different build unit, or even a different build method altogether, than is used for the object. For example, it may be advantageous to have one build unit that directs an e-beam, and another build unit that directs a laser beam. With respect to the build envelope, precision and quality of the envelope may be relatively unimportant, such that rapid build techniques are advantageously used. In general, the build envelope may be built by any suitable means, for instance by Mig or Tig welding, or by laser powder deposition. If the wall is built by additive manufacturing, then a different irradiation emission directing device can be used to build than wall than is used to build the object. This is advantageous because building the wall may be done more quickly with a particular irradiation emission directing device and method, whereas a slower and more accurate directing device and method may be desired to build the object. For example, the wall may be built from a rapidly built using a different material from the object, which may require a different build method. Ways to tune accuracy vs. speed of a build are well known in the art, and are not recited here. 
     For example, as shown in  FIG. 6 , the systems and methods of the present invention may use two or more build units to build one or more object(s). The number of build units, objects, and their respective sizes are only limited by the physical spatial configuration of the apparatus.  FIG. 6  shows a top down view of a large-scale additive manufacturing machine  800  according to an embodiment of the invention. There are two build units  802 A and  802 B mounted to a positioning system  801 . There are z crossbeams  803 A and  803 B for moving the build units in the z direction. There are x crossbeams  804 A and  804 B for moving the build units in the x direction. The build units  802 A and  802 B are attached to the x crossbeams  804 A and  804 B by mechanisms  805 A and  805 B that move the units in the y direction. The object(s) being formed are not shown in this view. A build envelope (also not shown in this view) can be built using one or both of the build units, including by laser powder deposition. The build envelope could also be built by, e.g., welding. In general, any number of objects and build envelopes can be built simultaneously using the methods and systems of the present invention. 
     Referring now to  FIG. 7 , a powder supply system  900  for providing additive powder  902  to hopper  904  of a powder dispenser  906  will be described according to an exemplary embodiment. As used herein, “additive powder” may be used to refer to any material deposited onto a build plate or build platform  908  of the additive manufacturing machine  910  or on top of a base layer or prior additively formed layer of powder that may be fused or bonded by an energy beam of an energy source such an irradiation emission directing device. The additive powder  902  may be any material suitable for fusing to form a part during the additive manufacturing process. Examples of such material include engineering plastics, thermoplastic elastomers, metals, and ceramics. However, it should be appreciated that other materials could be used according to alternative embodiments. 
     As illustrated in  FIG. 7 , additive manufacturing machine  910  defines a vertical direction (i.e., the Z-direction) and a horizontal plane H (e.g., defined by the X-direction and the Y-direction). Build platform  908  extends within the horizontal plane H to provide a surface for depositing layers of additive powder  902 , as described herein. In general, additive manufacturing machine  910  includes a build unit  920  that is generally used for depositing a layer of additive powder  902  and fusing portions of the layer of additive powder  902  to form a single layer of a component (not illustrated in  FIG. 7 ). As described above, build unit  920  forms the component layer-by-layer by printing or fusing layers of additive powder  902  as build unit  920  moves up along the vertical direction. 
     Build unit  920  generally includes a powder dispenser  906  for discharging a layer of additive powder  902  and an energy source  922  for selectively directing energy toward the layer of additive powder  902  to fuse portions of the layer of additive powder  902 . For example, powder dispenser  906  may include a powder hopper  904 , a system of gates (see, e.g.,  FIG. 4, 610A -C and  FIG. 5, 702A -C), a recoater arm  924 , and any other components which facilitate the deposition of smooth layers of additive powder  902  on build platform  908  or a sub layer. In addition, “energy source” may be used to refer to any device or system of devices configured for directing an energy beam towards a layer of additive powder  902  to fuse a portion of that layer of additive powder  902 . For example, according to an exemplary embodiment, energy source  922  may be an irradiation emission directing device as described above. 
     As described above, build unit  920  is described as utilizing a direct metal laser sintering (DMLS) or direct metal laser melting (DMLM) process using an energy source to selectively sinter or melt portions of a layer of powder. However, it should be appreciated that according to alternative embodiments, additive manufacturing machine  910  and build unit  920  may be configured for using a “binder jetting” process of additive manufacturing. In this regard, binder jetting involves successively depositing layers of additive powder in a similar manner as described above. However, instead of using an energy source to generate an energy beam to selectively melt or fuse the additive powders, binder jetting involves selectively depositing a liquid binding agent onto each layer of powder. For example, the liquid binding agent may be a photo-curable polymer or another liquid bonding agent. Other suitable additive manufacturing methods and variants are intended to be within the scope of the present subject matter. 
     Notably, according aspects of the present subject matter, build unit  920  is supported by a gantry  930  that is positioned above build platform  908  and at least partially defines a build area  932 . Notably, as used herein, “gantry”  930  is intended to refer to the horizontally extending support beams and not the vertical support legs  934  that support the gantry  930  over the build platform  908 . Although a gantry  930  is used to describe the support for build unit  920  herein, it should be appreciated that any suitable vertical support means can be used according to alternative embodiments. For example, build unit  920  may be attached to a positioning system such as a delta robot, a cable robot, a robot arm, a belt drive, etc. In addition, although build platform  908  is illustrated herein as being stationary, it should be appreciated that build platform  908  may move according to alternative embodiments. In this regard, for example, build platform  908  may be configured for translating along the X-Y-Z directions or may rotate about one of these axes. 
     According to the illustrated embodiment, gantry  930  defines a build area  932  having a maximum build width (e.g., measured along the X-direction), build depth (e.g., measured along the Y-direction), and build height (measured along the vertical direction or Z-direction). Gantry  930  is generally configured for movably supporting build unit  920  within build area  932 , e.g., such that build unit  920  may be positioned at any location (e.g., along X-Y-Z axes) within build area  932 . Moreover, according to exemplary embodiments, gantry  930  may further be configured for rotating build unit about the X, Y, and Z axes. Thus, build unit  920  may be positioned and oriented in any suitable manner within build area  932  to perform additive manufacturing process. 
     Notably, as described briefly above, powder dispenser  906  is capable of holding a limited volume of additive powder  902 . Thus, powder hopper  904  must be frequently refilled during the additive manufacturing process so that the powder dispenser  906  may continue to deposit layers of additive powder  902 . Powder supply system  900 , as described herein, is generally configured for refilling hopper  904  of powder dispenser  906 . 
     In general, as best illustrated in  FIG. 7 , additive manufacturing machine  910  includes a powder supply source  940  which is positioned external to gantry  930  or outside of build area  932  and is generally configured for continuously supplying additive powder  902  to powder dispenser  906 . More specifically, powder supply source  940  is generally sufficient for supplying all additive powder  902  necessary to complete a build process, which may fill the entire build area  932 . In this manner, operators of the additive manufacturing machine  910  may make sure that powder supply source  940  always has additive powder  902  ready and available for powder dispenser  906  in the event it needs a refill. 
     Powder supply system  900  generally includes any suitable number and type of apparatus, devices, or systems of components configured for transporting or conveying additive powder  902  from powder supply source  940  to powder dispenser  906 , e.g., directly into powder hopper  904 . According to the exemplary embodiment, powder supply system  900  is positioned below gantry  930  along the vertical or Z-direction and extends substantially within the horizontal plane H between powder supply source  940  and powder dispenser  906 . 
     More specifically, according to the illustrated embodiment, powder supply system  900  includes a conveyor  950  that transports additive powder  902  from powder supply source  940  to powder dispenser  906 . For example, conveyor  950  may be a simple belt conveyor, bucket conveyor, or any other suitable transport for additive powder  902  to powder dispenser  906 . According to still another embodiment, conveyor  950  is a vibrating belt conveyor which may vibrate to facilitate the movement of the additive powder  902 . Powder supply system  900  and conveyor  950  may include any suitable features for retaining and transporting additive powder between powder supply source  940  and build unit  920 . For example, conveyor  950  may include raised sides which prevent additive powder  902  from falling under the force of gravity. Alternatively, supply system may be a series of buckets or containers that move between powder supply source  940  and hopper  904 . According still another embodiment, powder supply system  900  may include a closed tube or conduit that urges additive powder  902  from powder supply source  940  to hopper  904 , e.g., under the force of gravity, via a screw drive mechanism, a pump mechanism, or any other suitable means. 
     Powder supply system  900  can extend from an intake  952  proximate powder supply source  940  to a discharge  954  proximate powder hopper  904 . Intake  952  may be any device or apparatus for depositing additive powder  902  onto conveyor  950 . Similarly, discharge  954  may be any suitable device or apparatus used to deposit, drop, or otherwise move additive powder  902  from conveyor  950  to powder hopper  904 . Thus, for example, powder supply source  940  may be periodically supplied additive powder  902  and may include a vertical drive screw or other mechanism for depositing the additive powder onto intake  952  of conveyor  950 . Conveyor  950  may then transport the additive powder  902  from outside of build area  932  into build area  932  in toward build unit  920 . Similarly, discharge  954  may include a telescoping chute  956  or some other dispensing mechanism for directing the additive powder  902  from conveyor  950  and into powder hopper  904 . According to another embodiment, powder supply source  950  may be manually supplied with additive powder  902 , e.g., by an operator of additive manufacturing machine  910 . Alternatively, the operator may deposit additive powder  902  directly onto conveyor  950  or into a device which continuously feeds conveyor  950  when hopper  904  needs to be refilled. Conveyor  950  may operate continuously, or when additive powders  902  are detected on conveyor  950 , to transport additive powder  902  from powder supply source  940  to build unit  920 . 
     Referring now to  FIG. 8 , a powder supply system  1000  and a powder reclamation system  1002  will be described according to an exemplary embodiment of the present subject matter. Powder supply system  1000  and powder reclamation system  1002  may be generally used to the refill a powder dispenser in an additive manufacturing machine. For example, according to the illustrated embodiment, powder supply system  1000  is configured for refilling a hopper  1004 , which may be attached to a build unit such as hopper  904  of additive manufacturing machine  910 . However, powder supply system  1000  and powder reclamation system  1002  can also be used for supplying additive powder  1006  to any other suitable additive manufacturing machine. 
     Powder supply system  1000  generally includes a powder supply source  1010 , such as a reservoir of additive powder  1006 . Powder supply source  1010  is generally configured for providing additive powder  1006  to the hopper of an additive manufacturing machine. For example, as illustrated in  FIG. 8 , powder supply source  1010  is operably coupled to a dosing valve  1012  for selectively providing a precise amount of additive powder  1006  onto a conveyor  1014 . Similar to the embodiment described above with regard to powder supply system  900 , conveyor  1014  may be configured for transporting the additive powder  1006  dispensed from the powder supply source  1010  to hopper  1004 . 
     Conveyor  1014  may comprise a discharge  1016  proximate hopper  1004 . For example, according to the illustrated embodiment, discharge  1016  is positioned above hopper  1004  along the vertical direction V. In this manner, additive powder  1006  may fall off of the end of conveyor  1014  under the force of gravity into hopper  1004 . In addition, discharge  1016  may be any suitable device or apparatus used to deposit, drop, or otherwise move additive powder  1006  from conveyor  1014  to hopper  1004 . Thus, for example, discharge  1016  may include a chute  1018  or some other dispensing mechanism for directing the additive powder  1006  from conveyor  1014  and into hopper  1004 . 
     Notably, the refill process of an additive manufacturing machine typically wastes a large amount of additive powder. For example, additive powder  1006  may frequently miss hopper  1004  when exiting discharge  1016  of conveyor  1014 , thus falling over the edge of hopper  1004  and down onto a work surface or elsewhere within the additive manufacturing machine. Similarly, inadvertent overfilling of the hopper  1004  can result in spillage of additive powder  1006 . Moreover, as additive powder  1006  is deposited into hopper  1004 , a plume of additive powder  1006  may be formed which may be deposited throughout the additive manufacturing machine and onto sensitive components. The build-up of additive powder  1006  within components of an additive manufacturing machine may result in serious operational issues. In addition, the misdirected additive powder  1006  is typically not reused, thus resulting in increased material waste and costs. Powder reclamation system  1002 , which will be described below according to an exemplary embodiment, is generally configured for collecting additive powder  1006  that is misdirected or inadvertently dispersed during the refill process. In this regard, additive powder  1006  that is dispensed from powder supply source  1010  during the refill process but does not reach hopper  1004  may be referred to herein generally as “misdirected powder.” 
     Although reference numeral  1006  is used herein to identify additive powder in  FIG. 8 , it should be appreciated that the additive powder  1006  may have different qualities or characteristics at different points within powder supply system  1000 . In this regard, for example, additive powder  1006  on conveyer  1014  is typically clean, new, sieved, filtered, etc. Once the additive powder  1006  becomes airborne above hopper  1004  or fails past hopper  1004 , i.e., misdirected powder, it is possible that this additive powder  1006  contains debris and/or contamination from elsewhere within powder distribution system  1000  or the surrounding environment. Thus, this misdirected additive powder  1006  may be cleaned or filtered, as described below. 
     Referring still to  FIG. 8 , powder reclamation system  1002  generally includes a vacuum pump  1030  that is operably coupled to a duct system  1032  for collecting misdirected additive powder  1006 . Vacuum pump  1030  may be any suitable type of pump configured for urging a flow of air, gas, and/or additive powder  1006  through duct system  1032  during a reclamation process where misdirected powders are collected. For example, vacuum pump  1030  may be a fan, a blower, or any other suitable type of compressive pump which generates a negative pressure within duct system  1032  for drawing in additive powder  1006 . 
     As illustrated, duct system  1032  includes an upper intake duct  1034 , a lower intake duct  1036 , and a return duct  1038 . In general upper intake duct  1034  and lower intake duct  1036  may each define a suction inlet  1040  positioned for drawing in a flow of additive powder  1006  and passing it toward vacuum pump  1030 . Vacuum pump  1030  merges the flow from intake ducts  1034 ,  1036  and returns it to powder supply source  1010  through return duct  1038 . It should be appreciated that although return duct  1038  is illustrated as returning collected additive powder  1006  back into powder supply source  1010 , some or all of additive powder  1006  could alternatively be routed for disposal, reconditioning, or for some other use. 
     Powder reclamation system  1002  may further include a filter mechanism  1050  that is operably coupled to return duct  1038  for removing any contaminants entrained within flow of additive powder  1006 . In this regard, for example, filter mechanism  1050  may be a simple filter screen, a sieve, a cyclonic separator, or any other suitable mechanism for filtering additive powder  1006 . In addition, filter mechanism  1050  may include a drying mechanism for regulating the humidity of collected additive powder  1006 , may be configured for breaking up clumps formed within additive powder  1006 , or may be configured for conditioning the return flow of additive powder  1006  and any other suitable manner. 
     Suction inlet  1040  may be positioned at any location suitable for capturing and collecting misdirected additive powder during a refill process. In this regard, upper intake duct  1034  and lower intake duct  1036  may be fixed relative to conveyor  1014 , may be fixed relative to hopper  1004 , or may move as necessary to collect misdirected powders. According to the illustrated embodiment, suction inlet  1040  of upper intake duct  1034  is positioned above discharge  1016  of conveyor  1014 . In this manner, upper intake duct  1034  is generally configured for drawing in the dust plume generated when additive powder is dropped off of conveyor  1014  and into hopper  1004 . In addition, suction inlet  1040  of lower intake duct  1036  may be positioned below hopper  1004 , e.g., to collect additive powder  1006  that misses or overflows out of hopper  1004  during the refill process. 
     According to an exemplary embodiment, suction inlet  1040  may generally include a vacuum shroud  1052  to facilitate improved capturing of misdirected additive powder  1006 . For example as illustrated in  FIG. 8 , suction inlet  1040  may include vacuum shroud  1052  which is sized and oriented for capturing all powder falling under the force of gravity. More specifically, referring to vacuum shroud  1052  on lower intake duct  1036 , vacuum shroud  1052  may define a shroud width  1054  that is larger than a hopper width  1056  of hopper  1004 . According still other embodiments, vacuum shroud  1052  may have any suitable size, shape, and position drawing in additive powder  1006 . 
     As illustrated in  FIG. 8 , duct system  1032  is operably coupled with a single vacuum pump  1030  which generates a vacuum for drawing in additive powder  1006 . However, it should be appreciated that according to alternative embodiments, any suitable number of vacuum pumps may be used, each of which may be coupled to any suitable number of return ducts or filtering systems for optimally gathering, filtering, separating, or otherwise processing reclaimed additive powder  1006 . 
     According to an exemplary embodiment the present subject matter, the hopper  1004  is coupled to a build unit which moves throughout a build area of the additive manufacturing machine. Thus, build unit may be configured for moving hopper  1004  to a refill station where powder supply system  1000  and powder reclamation system  1002  are located. According to such an embodiment, powder supply system  1000 , powder reclamation system  1002 , and powder supply source  1010  are all fixed within the additive manufacturing machine, e.g., relative to a gantry. However, it should be appreciated that according to alternative embodiments, these systems may be mobile such that some or all of them may move toward the build unit, e.g., into the build area, when hopper  1004  needs to be refilled. More specifically, according such embodiment, conveyor  1014 , upper intake duct  1034 , and lower intake duct  1036  may extend out to or otherwise move with hopper  1004  during a refill process. Other configurations are possible and within scope of the present subject matter. 
     Referring now to  FIG. 9 , a gate cleaning system  1100  for an additive manufacturing machine will be described according to an example embodiment. As illustrated, the additive manufacturing machine includes a powder dispenser  1102  that defines a plurality of gates  1104  for dispensing additive powder  1106 . According to an exemplary embodiment, powder dispenser  1102  may further include gate plates (not shown in  FIG. 9 ; similar to gate plate  410  from  FIG. 2 ) that are associated with each of the plurality of gates  1104 . As described above, powder dispenser  1102  may further include one or more actuators (not shown in  FIG. 9 ; similar to actuator  412  from  FIG. 2 ) configured for selectively opening and closing the gate plates to regulate the flow of additive powder  1106  through gates  1104 . 
     As will be described in detail below, gate cleaning system  1100  is generally configured for ensuring the proper flow of additive powder  1106  through gates  1104  and onto a build platform or sub layer of additive powder  1106 . In this regard, for example, gate cleaning system  1100  may be configured for cleaning gates  1104 , dislodging clogged additive powder  1106 , detecting one or more powder properties, or otherwise facilitating an improved powder dispensing process as will be describe below. 
     Referring to  FIG. 9 , gate cleaning system  1100  includes a cleaning head  1110  having a plurality probes  1112  that extend from cleaning head  1110  to selectively engage the plurality of gates  1104  to unclog additive powder  1106 . In this regard, according to the exemplary illustrated embodiment, probes  1112  are prongs, bristles, or other protrusions extending along a vertical direction (e.g., the Z-direction) from a top of cleaning head  1110 . Although the illustrated embodiment shows five gates  1104  and a single probe  1112  associated with each gate  1104 , it should be appreciated that cleaning head  1110  may define, and each gate  1104  may associated with, any suitable number, size, and configuration of cleaning probes or instruments for cleaning that respective gate  1104 . 
     During the gate cleaning operation, gate cleaning system  1100  is configured for moving cleaning head  1110  along the vertical direction V (or the Z-direction) toward powder dispenser  1102  for engaging the plurality of gates  1104 . In this regard, for example, gate cleaning head  1110  may position probes  1112  physically within gates  1104  for contacting clogged powders (e.g., as identified by reference numeral  1114 ), thereby removing such clogs and permitting smooth in uniform flow of additive powder  1106  from gates  1104 . The depth of penetration, the movement of probes  1112  within gates  1104 , and other features associated with probes  1112  (some of which are described below according to exemplary embodiments) may be adjusted to ensure effective cleaning of gates  1104 . 
     According to an illustrated embodiment, gate cleaning system  1100  may be located at a refill station and may perform a cleaning operation before, during, or after powder dispenser  1102  is refilled with additive powder  1106 . For example, gate cleaning head  1110  can be positioned proximate powder supply system  1000  and powder reclamation system  1002  as described above. These systems may work together to clean powder dispenser  1102  and gates  1104 , to refill powder dispenser  1102  with additive powder  1106  for subsequent powder application, and to reclaim powder lost during the refill process. Other configurations and embodiments are possible and within scope of the present subject matter. 
     According to the exemplary embodiment, gate cleaning head  1110  is configured for moving along the vertical direction upward to engage gates  1104  of a stationary powder dispenser  1102 . However, it should be appreciated that according to alternative embodiments a cleaning head  1110  may move in any other suitable manner and in any other suitable angle or direction for engaging gates  1104  of powder dispenser  1102 . Moreover, according to alternative embodiments, gate cleaning head  1110  may remain stationary while powder dispenser  1102  moves into engagement with probes  1112 . Thus, any suitable movement of gate cleaning head  1110  and/or powder dispenser  1102  may be used to effectively clean gates  1104 . 
     Referring still to  FIG. 9 , gate cleaning system  1100  may include additional features for cleaning gates  1104  or otherwise ensuring the quality of dispensed additive powder  1106 . For example, each of the plurality of probes  1112  may be in fluid communication with a gas regulation device  1130 . According to one embodiment, gas regulation device  1130  is a source of compressed gas. In this manner, gate cleaning head  1110  and probes  1112  may define internal passageways  1132  that are configured for routing and directing a flow of cleaning gas out of a discharge port  1134  positioned on a tip of each probe  1112 . Thus, gas regulation device  1130  may urge the flow of gas through internal passageways  1132  and out of probes  1112  through discharge ports  1134 . The flow of gas can be directed into or around gates  1104  to dislodge clogged powder, remove contaminants, or otherwise facilitate a cleaning process to gates  1104 . According to such an embodiment, probes  1112  may fully enter through gates  1104  or may be positioned remote from gates  1104  and may simply direct a flow of gas into gates  1104 . 
     According still another embodiment, gas regulation device  1130  may instead be a vacuum source for drawing in air, gases, and additive powder  1106  through probes  1112  and internal passageways  1132 . According to such an embodiment, probes  1112  be positioned proximate to gates  1104  and may be configured for drawing out powder clogs and contaminants. The collected additive powder  1106  may be disposed of or may be reused. For example, according to one embodiment, the vacuum source is operably coupled with a powder reclamation system of an additive manufacturing machine, such as powder reclamation system  1002 . 
     It should be appreciated that gas regulation device  1130  may be configured for providing a flow of compressed gas or providing suction to all probes  1112  simultaneously or to one or more probes  1112  independently as needed. For example, it may be desirable only to provide a flow of compressed gas to a gate  1104  that is clogged with additive powder  1106 . Therefore internal passageways  1132  and/or each probe  1112  can include a valve or shut off (not shown) that is configured for stopping the flow of gas or air through that particular probe  1112 . Other configurations of gate cleaning system  1100  and gas regulation device  1130  are possible and within the scope of the present subject matter. 
     Gate cleaning system  1100  may further include any suitable number and type of sensor  1140  for detecting a powder property of additive powder  1106 . For example, sensors  1140  may be positioned on probes  1112  for direct contact with additive powder  1106  during a cleaning operation. In this manner, sensors  1140  may be configured for detecting powder properties or quality characteristics and using information regarding those characteristics to improve the performance of gate cleaning system  1100  and the operation of the additive manufacturing machine. 
     As used herein, “powder properties” may be used to refer to any characteristic of additive powder  1106  which may affect the flow of additive powder  1106  through gates  1104 , the quality of additive powder  1106  deposited for subsequent fusion, or otherwise affect the additive manufacturing process. For example, powder properties may include a flow rate of additive powder  1106  from one or more gates  1104 , the humidity of additive powder  1106 , the presence or absence of additive powder  1106 , the presence of clogs, or any other suitable characteristic of additive powder  1106 . 
     According to an exemplary embodiment, gate cleaning system  1100  may further include a vision system  1150  that is configured for detecting and correcting the alignment of probes  1112  and gates  1104  during the gate cleaning process. In this regard, when gate cleaning head  1110  moves upward into engagement with powder dispenser  1102 , it may be desirable to ensure probes  1112  are centered within each of their respective gates  1104 . Thus, vision system  1150  may monitor the position of some or all of probes  1112  and gates  1104  to provide feedback to a controller (not shown) that regulates the movement of gate cleaning had  1110 . Vision system  1150  may be, for example, a camera, a proximity sensing system, the laser distance measuring system, or any other suitable system for detecting the position of one or more objects within a three-dimensional space. 
     Although gate cleaning system  1100  as described above as an independent system for cleaning gates  1104  of powder dispenser  1102  of an additive manufacturing machine, it should be appreciated that gate cleaning system  1100  may be incorporated into a powder reclamation system, such as powder reclamation system  1002  described above. In this regard, for example, gas regulation device  1130  may be operably coupled with vacuum pump  1030  or duct system  1032  for collecting, filtering, and reusing collected additive powder  1106 . For example, vacuum shroud  1052  of lower intake duct  1036  may be positioned below cleaning head  1110  for collecting additive powder  1106  that is dislodged from gates  1104  during a cleaning operation. 
       FIG. 10  depicts a block diagram of an example control system  150  that can be used to implement methods and systems according to example embodiments of the present disclosure, particularly the operation of powder supply system  1000 , powder reclamation system  1002 , gate cleaning system  1100 , or any other systems of additive manufacturing machine. As shown, the control system  150  can include one or more computing device(s)  152 . The one or more computing device(s)  152  can include one or more processor(s)  154  and one or more memory device(s)  156 . The one or more processor(s)  154  can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, or other suitable processing device. The one or more memory device(s)  156  can include one or more computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, or other memory devices. 
     The one or more memory device(s)  156  can store information accessible by the one or more processor(s)  154 , including computer-readable instructions  158  that can be executed by the one or more processor(s)  154 . The instructions  158  can be any set of instructions that when executed by the one or more processor(s)  154 , cause the one or more processor(s)  154  to perform operations. The instructions  158  can be software written in any suitable programming language or can be implemented in hardware. In some embodiments, the instructions  158  can be executed by the one or more processor(s)  154  to cause the one or more processor(s)  154  to perform operations, such as the operations for controlling the operation of an additive manufacturing machine. 
     The memory device(s)  156  can further store data  160  that can be accessed by the one or more processor(s)  154 . For example, the data  160  can include any data used for operating an additive manufacturing machine, as described herein. The data  160  can include one or more table(s), function(s), algorithm(s), model(s), equation(s), etc. for operating an additive manufacturing machine according to example embodiments of the present disclosure. 
     The one or more computing device(s)  152  can also include a communication interface  162  used to communicate, for example, with the other components of the system. The communication interface  162  can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, or other suitable components. 
     The powder supply, reclamation, and gate cleaning systems described above provide several advantages compared to conventional powder supply systems. For example, by using powder supply and reclamation systems, a hopper may be refilled precisely and without wasting large amounts of additive powder. In this regard, misdirected additive powder may be collected and returned to the powder reservoir for reuse, thereby eliminating waste and reducing operational costs. In addition, powder reclamation system reduces or eliminates the build-up of additive powder throughout additive manufacturing machine, which may result in operational issues and degradation of finished component quality. The gate cleaning system ensures that additive powder is smoothly and uniformly deposited layer-by-layer onto a build platform or sublayer of additive powder to facilitate an improved additive manufacturing process. Other advantages to powder supply, reclamation, and gate cleaning systems will be apparent to those skilled in the art. 
     This written description uses exemplary embodiments to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.