SYSTEM AND METHOD FOR POSITIONING A 3D PART ON A BUILD PLATE

A method for printing a 3D part includes receiving a print plan for the 3D part. The method also includes scanning a build plate, onto which the 3D part will be printed, to produce a scan that comprises a topography of an upper surface of the build plate. The method also includes comparing the print plan and the scan. The method also includes determining a recommended position to print the 3D part on the build plate based at least partially upon the comparison.

TECHNICAL FIELD

The present teachings relate generally to three-dimensional (3D) printing and, more particularly, to systems and methods for selecting where on a build plate to build (i.e., print) a 3D part based at least partially upon a topography of the build plate.

BACKGROUND

Three-dimensional (3D) printing jets a liquid build material through an ejector. A plurality of drops of the liquid build material are ejected from a nozzle of the ejector. The drops fall onto a build plate where they cool and solidify to form a 3D part. For the best outcomes, the build plate should be flat. More particularly, the upper surface of the build plate, where the drops will land, should be free of defects such as warpage that may not be visible to the eye.

Laser scanners may provide a topographical image of the build plate; however, the operator then has to manually evaluate the topographical image to determine if the 3D part should be printed on the build plate, and/or where the 3D part should be printed on the build plate for the best results. Manual evaluation of the scan requires the operator to understand how to interpret the scan and what tolerances are acceptable for the 3D part being printed. Based on learned knowledge and experience, the operator then offsets the 3D part by manually entering coordinates.

SUMMARY

A method for printing a 3D part is disclosed. The method includes receiving a print plan for the 3D part. The method also includes scanning a build plate, onto which the 3D part will be printed, to produce a scan that comprises a topography of an upper surface of the build plate. The method also includes comparing the print plan and the scan. The method also includes determining a recommended position to print the 3D part on the build plate based at least partially upon the comparison.

In another embodiment, the method includes receiving a print plan. The print plan includes a size and a shape of the 3D part, a size and a shape of supports, a planned position of the 3D part and the supports on a build plate, and a planned orientation of the 3D part and the supports on the build plate. The method also includes scanning the build plate. The build plate is scanned before a first layer of the 3D part and the supports is printed. Scanning the build plate produces a scan that includes a topography of an upper surface of the build plate including: a flat surface, an area that is vertically offset from the flat surface by greater than a predetermined threshold, and an interface between the flat surface and the area. The predetermined threshold is from about 0.05 mm and about 0.30 mm. The method also includes comparing the print plan and the scan. Comparing the print plan and the scan includes overlaying the print plan onto the scan with the 3D part and supports in the planned position on the build plate. The method also includes determining a recommended position of the 3D part and the supports on the build plate based at least partially upon the comparison. The recommended position is laterally-offset from the planned position. The recommended position of the 3D part is on the flat surface, the area, or both, but not on the interface. The method also includes determining a recommended orientation of the 3D part and the supports on the build plate based at least partially upon the comparison. The method also includes printing the 3D part and the supports in the recommended position and the recommended orientation on the build plate.

A 3D printer is also disclosed. The 3D printer includes an ejector configured to receive a build material. The ejector includes a nozzle. A plurality of drops of the build material are ejected through the nozzle in a liquid state. The 3D printer also includes a build plate positioned below the nozzle. The drops land on the build plate and cool and solidify thereon to form a 3D part. The 3D printer also includes a scanner configured to scan the build plate to produce a scan that includes a topography of an upper surface of the build plate. The 3D printer also includes a computing system configured to: receive a print plan for the 3D part; receive the scan; compare the print plan and the scan; and determine a recommended position to print the 3D part on the build plate based at least partially upon the comparison.

DETAILED DESCRIPTION

FIG.1depicts a schematic cross-sectional side view of a 3D printer100, according to an embodiment. The printer100may include an ejector (also referred to as a pump)110. As used herein, the ejector110refers to a structure that can be selectively activated to cause a build material120to be ejected from a nozzle114of the ejector110. As used herein, the nozzle114refers to a physical structure from which the build material120begins flight.

The ejector110may define a reservoir (also referred to as an ejector reservoir)112that is configured to receive and/or store the build material120that is to be ejected from the nozzle114. The build material120may be or include a metal, a polymer, or the like. In one embodiment, the build material120may be greater than about 50% metal, greater than 60% metal, greater than 70% metal, greater than 80% metal, greater than 90% metal, or about 100% metal (e.g., by volume and/or mass). For example, the build material120may be or include a spool of aluminum wire (e.g., 6061 aluminum). In another embodiment, the build material120may be or include copper or other metals.

The 3D printer100may also include one or more heating elements130. The heating elements130are configured to melt the build material120within the ejector reservoir112, thereby converting the build material120from the solid state to the liquid (e.g., molten) state within the ejector reservoir112.

The 3D printer100may also include a power source132and one or more metallic coils134. The metallic coils134are wrapped at least partially around the ejector110and/or the heating elements130. The power source132may be coupled to the coils134and configured to provide power thereto. In one embodiment, the power source132may be configured to provide a step function direct current (DC) voltage profile (e.g., voltage pulses) to the coils134, which may create an increasing magnetic field. The increasing magnetic field may cause an electromotive force within the ejector110, that in turn causes an induced electrical current in the liquid build material120. The magnetic field and the induced electrical current in the liquid build material120may create a radially inward force on the liquid build material120, known as a Lorentz force. The Lorentz force creates a pressure at an inlet of the nozzle114of the ejector110. The pressure causes the liquid build material120to be jetted through and/or ejected from the nozzle114in the form of one or more drops122.

The 3D printer100may also include a build plate (also referred to as a substrate)140that is positioned below the nozzle114. The drops122may be ejected from the nozzle114and subsequently land on the build plate140where they may cool and solidify to form a first (e.g., bottom) layer. Additional drops122may be jetted to form layer upon layer that eventually produces a 3D part124. As mentioned above, the upper surface of the build plate140may have one or more areas that are not flat (e.g., warpages or defects). Printing the 3D part124onto an area of the build plate140that is not flat may cause the 3D part124to deviate from the planned design.

The 3D printer100may also include a scanner150. The scanner150may be or include a laser scanner that is configured to scan the topography of the upper surface of the build plate140.

The 3D printer100may also include a computing system160. As described below, the computing system160may receive planned design of the 3D part124as well as the scan from the topography scanner150. The computing system160may determine whether and/or where to print the 3D part124on the build plate140based at least partially upon the planned design and the scan. The computing system160may also or instead determine an orientation of (e.g., how to move/rotate) the 3D part124prior to printing based at least partially upon the planned design and the scan.

FIG.2depicts a flowchart of a method200for printing the 3D part124, according to an embodiment. More particularly, the method200may determine (e.g., recommend) a position to print the 3D part124on the build plate140. The method200may be performed by the 3D printer100(e.g., the computing system160). An illustrative order of the method200is provided below; however, one or more steps of the method200may be performed in a different order, repeated, combined, or omitted.

The method200may include determining or receiving a print plan, as at210.FIG.3depicts a schematic view of a print plan300including the 3D part124and supports126, according to an embodiment. The drops122may cool and solidify on the build plate140to form both the 3D part124and the supports126. The supports126may be positioned at least partially between the build plate140and one or more portions of the 3D part124. In an example, the portions of the 3D part124may be or include overhangs. After printing is completed, the supports126may be removed (e.g., machined away) to yield the 3D part124. Thus, the supports126may be sacrificial.

In one embodiment, the print plan300may include the size and/or shape of the 3D part124and supports126. The print plan300may also include also include a first (e.g., planned) position on the build plate140where the 3D part124and the supports126will be printed. The print plan300may also include a planned orientation of the 3D part124and the supports126on the build plate140.

The method200may also include scanning the build plate140, as at220.FIG.4depicts a schematic view of a scan400of the build plate140, according to an embodiment. The scan (also referred to as a first scan)400may be performed by the scanner150on the upper surface of the build plate140(e.g., before printing begins). The first scan400may show that the upper surface of the build plate140includes a substantially flat surface410. As used herein, the term “flat” or “substantially flat” (e.g., flat surface) includes a vertical topography deviation that is less than a predetermined threshold. The predetermined threshold may be from about 0.05 mm to about 0.50 mm, about 0.05 mm to about 0.30 mm, or about 0.10 to about 0.20 mm (e.g., 0.15 mm). In one embodiment, the flat surface 410 may include greater than 10%, greater than 25%, greater than 50%, greater than 60%, greater than 70%, greater than 80%, or greater than 90% of the area of the upper surface of the build plate140.

The first scan400may show that the upper surface of the build plate140also includes an area420that deviates (e.g., vertically) from the flat surface410by more than the predetermined threshold. Thus, the area420may not be (e.g., horizontally) aligned with the flat surface410.

More particularly, the area420may be above and/or below the flat surface410by more than the predetermined threshold. In the example shown, the area420is parallel with the flat surface410. In other embodiments, the area420may not be parallel. For example, the area420may be curved, uneven, or the like.

An interface430may exist between the flat surface410and the area420. The interface430represents the (e.g., vertical) transition therebetween. Thus, the area420, the interface430, or the combination thereof may be convex (i.e., protrude upward) or concave (i.e., protrude downward) with respect to the flat surface410. In an example, the area420and/or the interface430may protrude (e.g., in the vertical direction) by more than about 0.15 mm from the flat surface410.

The method200may also include comparing the print plan300and the first scan400, as at230. For example, the print plan300may be combined with (e.g., overlaid upon) the first scan400.FIG.5depicts a schematic view of the print plan300overlaid upon the first scan400, according to an embodiment. More particularly,FIG.5depicts a first (e.g., default or planned) position of the 3D part124and the supports126on the build plate140(e.g., based upon the print plan300). As shown inFIG.5, a portion of the 3D part124is initially planned to be printed on the interface430. Printing the 3D part124on the interface430may cause the 3D part124to deviate from the planned design.

The method200may also include determining a second (e.g., recommended and/or actual) position of the 3D part124and supports126on the build plate140, as at240. As mentioned above, the computing system160may determine the second position based at least partially upon the print plan300, the first scan400, the comparison, or a combination thereof. The second position may be a lateral translation in the horizontal (e.g., X-Y) plane on the build plate140from the first position. The second position may also or instead include an orientation change (e.g., a rotation) from the first position.

In an embodiment, the second position may be determined based at least partially upon the first position. For example, when the 3D part124is sliced for printing, it may be pre-positioned on the X-Y coordinates on the build plate140, or the first position may default to the center of the build plate140. The initial coordinates for the 3D part124and supports126may be utilized by the computing system160to determine the required offsets and/or rotation of the 3D part124and supports126based upon the print plan300, the first scan400, the comparison, and/or the acceptable tolerances.

In another embodiment, the second position may be determined based at least partially upon the X-Y coordinates of the supports126versus the 3D part124. More particularly, the supports126may be printed to support overhangs of the 3D part124. Although it may be optimal to have the supports126printed over a flat area of the build plate140, it is not required as they may be removed during post-printing processing (e.g., machining). As discussed below, the first layer of the 3D part124may be analyzed and compared to the build plate health. The finished 3D part124may take priority placement over the supports126. The method200may consider the positioning of the 3D part124and the supports126independently for optimal X-Y placement and rotation of both parts.

In another embodiment, the second position may be determined based at least partially upon the identification of the build plate140. The computing system160may know the specific build plate140being used (e.g., not the part number but the actual build plate) so that it may analyze the history of the build plate140and previous 3D parts printed thereon.

In another embodiment, the second position may be determined based at least partially upon the build plate warpage topographical tolerance.FIG.6depicts a schematic view of another scan of the build plate140, according to an embodiment. By default, the printing job may be recommended to be printed within a predetermined topography deviation (e.g., 0.15 mm or less). The topography deviation refers to the vertical distance from the flat surface410of the build plate140. The tolerance level may be evaluated and modified to use more or less of the build plate surface area when determining the second position.

In another embodiment, the second position may be determined based at least partially upon prior X-Y printed coordinates. More particularly, the computing system160may analyze the printing of previous 3D parts on the build plate140to select areas that have not been overly used for printing. As used herein, “overly used” refers to a location where fewer than a predetermined number of 3D parts (e.g., three 3D parts) and/or supports have been printed. Although the warpage of the build plate140can change from print-to-print (e.g., due to thermal shock), the actual surface of the build plate140can also degrade over time. Based on the size of the job (e.g., the printing of the 3D part124and supports126), multiple areas of the build plate140may be acceptable. However, the computing system160may select for the second position an area of the build plate140that has been utilized the least for printing.

In another embodiment, the second position may be determined based at least partially upon a print optimization. As described below, the computing system160may perform a print optimization based on scans of one or more layers of the 3D part124and/or supports126during printing. The computing system140may consider corrections made to the first several layers along with the build plate topography to determine if adjustments to acceptable build plate warpage tolerances should be made for the current print job or future print jobs.

In another embodiment, the second position may be determined based at least partially upon the material (e.g., alloy) being used as the build material120. Different materials may have different properties that may impact the acceptable tolerance of build plate health and therefore the positioning of the 3D part124on the build plate140.

In another embodiment, the second position may be determined based at least partially upon the print quality settings. When the job is sliced, print quality settings may be applied. Higher or lower quality print settings may impact acceptable build plate topographical tolerances. The computing system160may take this into consideration when it determines the second position of the 3D part124and/or supports126on the build plate.

FIGS.7A and7Bdepict schematic views of second (e.g., recommended) positions of the 3D part124and supports126on the build plate140, according to an embodiment. More particularly,FIG.7Ashows the 3D part124and supports126printed on the flat surface410(e.g., outside of the area420and interface430). In another embodiment, the 3D part124may be printed outside the area420, and the supports126may be printed on the area420and/or the interface430.FIG.7Bshows the 3D part124printed on the area420and the supports126printed on the area420and/or the interface430. In these examples, the first scan400shows that, while the area420has a different depth than the flat surface410, the area420itself is also substantially flat. As such, the 3D part124may be printed on the area420.

Referring back toFIG.2, the method200may also include building (e.g., printing) the 3D part124and the supports126in the second position on the build plate140, as at250. Printing in/on the second position (as opposed to the first position) may reduce the printing time, the amount of build material120used, and the amount of machining required after printing because additional time, build material120, and machining are required to offset the depth variations when printing on the interface430.

The method200may also include monitoring a print quality of the 3D part124and/or the supports126, as at260. The print quality may be monitored during printing (e.g., after a first layer is printed and before a second layer is printed) or after printing is complete. More particularly, monitoring the print quality may include scanning the build plate140, the 3D part124, the supports126, or a combination thereof, as at262. This may include a different scan (also referred to as second scans) after each layer is printed. For example, a second scan may be performed by the scanner150on the upper surface of the first layer of the 3D part124and/or supports126.

Monitoring the print quality may also include comparing the print plan300and the second scan(s), as at264. In other words, the printed portion (e.g., layer) of the actual 3D part124and/or the supports126may be compared to the corresponding portion of the 3D part124and/or the supports126in the print plan300. This may include determining a deviation (e.g., difference) between the printed portion and the corresponding portion in the print plan300. The deviation may be between the printed and planned shapes, the printed and planned sizes, the printed and planned print times, the printed and planned amount of build material used, the printed and planned machining required, or a combination thereof.

Monitoring the print quality may also include adjusting the building (e.g., printing) the 3D part124and the supports126, as at266. The adjustment may be in response to the comparison. For example, in response to the upper surface of the (e.g., first) layer of the 3D part124and/or the supports126not being flat or otherwise deviating from the print plan300by more than a predetermined amount, adjusting the building may include depositing more or less build material120than planned in the non-flat X-Y location to make the upper surface of the next layer flat in that X-Y location. The print quality may also or instead be used to determine whether (e.g., how much) the recommended second position improved the parameters (e.g., size, shape, print time, build material, machining, etc.) when compared to the first position. This information may be used to calibrate the method200to adjust recommendations for the second position to improve the printing of future 3D parts.

The method200may also including removing the supports126, as at270. The supports270may be removed after printing is complete. As mentioned above, the supports270may be machined away to yield only the 3D part124.

The method200may be automated to reduce the print time and reliance on human evaluation and error. It also reduces post-print processing (e.g., machining) by ensuring that the layers (e.g., the first layer) of the 3D part124is flat. In contrast, conventional technologies address compensating for build plate defects by altering the amount of build material deposited on the build plate. The system and method described herein improve upon this by automatically positioning the 3D part124in different (e.g., best) location on the build plate140. This may reduce material waste, reduce the need for programmatic adjustments while printing, reduce post-print machining of the bottom layer, and improve removal from the build plate surface.

While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, it may be appreciated that while the process is described as a series of acts or events, the present teachings are not limited by the ordering of such acts or events. Some acts may occur in different orders and/or concurrently with other acts or events apart from those described herein. Also, not all process stages may be required to implement a methodology in accordance with one or more aspects or embodiments of the present teachings. It may be appreciated that structural objects and/or processing stages may be added, or existing structural objects and/or processing stages may be removed or modified.

Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” The term “at least one of” is used to mean one or more of the listed items may be selected. Further, in the discussion and claims herein, the term “on” used with respect to two materials, one “on” the other, means at least some contact between the materials, while “over” means the materials are in proximity, but possibly with one or more additional intervening materials such that contact is possible but not required. Neither “on” nor “over” implies any directionality as used herein. The term “conformal” describes a coating material in which angles of the underlying material are preserved by the conformal material. The term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. The terms “couple,” “coupled,” “connect,” “connection,” “connected,” “in connection with,” and “connecting” refer to “in direct connection with” or “in connection with via one or more intermediate elements or members.” Finally, the terms “exemplary” or “illustrative” indicate the description is used as an example, rather than implying that it is an ideal. Other embodiments of the present teachings may be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the present teachings being indicated by the following claims.