System and method for high throughput additive manufacturing of sintered parts with low anisotropy

Patent metadata

Field	Value
Publication number	US-11938537-B2
Application number	US-202217878538-A
Country	US
Kind code	B2
Filing date	Aug 1, 2022
Priority date	Aug 1, 2022
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

A 3D printing system and methods to selectively pattern dense feedstock based on selective inhibition sintering (SIS). A sintering selectivity agent (inhibitor or promoter) is selectively deposited on a build layer according to the pattern boundary. When the layers are built-up and the part is sintered, the inhibited region remains unbound, thus defining the edge of the part. The material contain powder embedded in cohesive binder that make the adjacent layer adhere together. The build process involves forming the sheets of dense feedstock embedded binder, followed by depositing ink to promote selective sintering onto the layer. Once the build is complete, the process continues with the binder removal, sintering and finishing processes.

First claim

What is claimed is:

1. A method for selectively patterning a dense sinterable additive manufactured feedstock structure into a 3D part with a 3D printing system, the method comprising:
a) forwarding a web sheet having a layer of dense feedstock in a process direction with a transfer subsystem of a printing system, the feedstock being a dense sinterable material and binder composite with porosity below 20% volume, the web sheet sectioned into dense feedstock 3D slices having slice boundary sections therebetween, the slices having an imaging area thereon;
b) selectively depositing a sintering ink according to a 3D pattern onto the imaging area of one of the dense feedstock 3D slices, the sintering ink infiltrating into the dense feedstock 3D slices to form patterned dense feedstock slices in accordance with the 3D pattern;
c) stacking the patterned dense feedstock slices over a previously formed patterned dense feedstock slice to form a build monolith having a plurality of patterned dense feedstock slices;
d) removing at least some of the binder composite from the build monolith; and
e) sintering the build monolith into the 3D part shaped based on the 3D pattern.

2. The method of claim 1 , further comprising, before step c), cutting the layer of dense feedstock at the slice boundary sections into the dense feedstock slices.

3. The method of claim 2 , the cutting at the slice boundary sections segregating the dense feedstock slices into separate dense feedstock slices.

4. The method of claim 1 , the step c) stacking including folding the individual patterned dense feedstock slices along the weekend sections on top of a build support to build the monolith.

5. The method of claim 1 , further comprising, before step a), depositing the layer of dense feedstock onto a substrate to form the web sheet, the substrate being a support non-integral to the 3D part.

6. The method of claim 5 , wherein the depositing includes depositing at least one of a metal powder and a ceramic powder that forms the layer of dense feedstock.

7. The method of claim 5 , wherein the depositing the layer of dense feedstock includes depositing a powder including one of metal and ceramic, and depositing a binder to make a cohesive feedstock sheet.

8. The method of claim 7 , wherein the binder includes a polymer, and step d) includes removing binder from the build monolith via one of solvent debind and thermal debind.

9. The method of claim 5 , further comprising, before Step c), removing the substrate from the patterned dense feedstock slices.

10. The method of claim 1 , further comprising surface finishing the 3D part.

11. The method of claim 1 , further comprising, after step a), priming the layer of dense feedstock for compatibility with the sintering ink, the priming including one of applying heat to ablate/evaporate/transform the binder in areas where the sintering ink is to penetrate, applying an oxygen plasma or ion bombardment to make the binder more hydrophilic, and applying a solvent-based ink formulation to dissolve the binder in areas where the sintering ink is to penetrate.

12. The method of claim 1 , wherein in step b) the selectively depositing is carried out through a pattern-wise process or by coating onto a selectively primed surface, and by spraying, screen printing, digital printing, inkjet printing, or offset printing the sintering ink.

13. The method of claim 1 , wherein the sintering ink includes one of a sintering inhibitor to be deposited on the negative space or boundary of the pattern, and a sintering promoter to be deposited in the positive space of the pattern.

14. The method of claim 1 , after step b), further comprising activating the sintering ink to transform the active selective-sintering material in the sintering ink from a state that is easily carried by the sintering ink as a solution or emulsion, to a state that doesn't leach out or diffuse after deposition, the activating including applying heat or gas flow to dry the sintering ink and leave a solid residue of the active material or applying heat, UV, or an energy source to cause a chemical reaction or decomposition reaction to transform a precursor in the sintering ink into a fully-functioning sintering inhibitor, or sintering-selectivity agent.

15. The method of claim 1 , wherein the sintered 3D part has low anisotropy having differences in material properties being below about 20% in the process direction in comparison to an orthogonal direction.

16. The method of claim 1 , wherein the Step c) further comprises bonding the plurality of patterned dense feedstock slices by applying at least one of heat and pressure to the stacked patterned dense feedstock slices.

17. The method of claim 16 , wherein the Step c) bonding occurs via interaction of the binder composite in adjacent ones of the stacked patterned dense feedstock slices.

18. A method for selectively patterning a dense sinterable additive manufactured feedstock structure into a 3D part with a 3D printing system, the method comprising:
a) forwarding a web sheet having a layer of dense feedstock in a process direction with a transfer subsystem of a printing system, the feedstock being a dense sinterable material and binder composite with porosity below 20% volume, the layer of dense feedstock being a dense feedstock 3D slice having imaging areas thereon;
b) selectively depositing a sintering ink according to a 3D pattern onto the imaging areas of the dense feedstock 3D slice, the sintering ink infiltrating into the dense feedstock 3D slice to form a patterned dense feedstock slice in accordance with the 3D pattern;
c) winding the patterned dense feedstock slice over a previously formed patterned dense feedstock slice section to form a build monolith;
d) removing at least some of the binder composite from the build monolith; and
e) sintering the build monolith into the 3D part shaped based on the 3D pattern.

19. The method of claim 18 , further comprising, before step c), winding the previously formed patterned dense feedstock slice section over an axial support.

20. The method of claim 18 , further comprising, before step a), depositing the layer of dense feedstock onto a substrate to form the web sheet, and before Step c), removing the substrate from the patterned dense feedstock slice.

21. A method for selectively patterning a dense sinterable additive manufactured feedstock structure into a 3D part with a 3D printing system, the method comprising:
a) forwarding a plurality of web sheets including a plurality of dense feedstock 3D slices in a process direction with a transfer subsystem of a printing system, the 3D slices including feedstock having a dense sinterable material and binder composite with porosity below 20% volume, the 3D slices having an imaging area thereon;
b) selectively depositing a sintering ink according to a 3D pattern onto the imaging area of the dense feedstock 3D slices, the sintering ink infiltrating into the dense feedstock 3D slices to form patterned dense feedstock slices in accordance with the 3D pattern;
c) stacking the patterned dense feedstock slices over a previously formed patterned dense feedstock slice to form a build monolith of the patterned dense feedstock slices;
d) removing at least some of the binder composite from the build monolith; and
e) sintering the build monolith into the 3D part shaped based on the 3D pattern.

22. The method of claim 21 , the web sheets having a substrate under the dense feedstock 3D slices, the m

Assignees

• Palo Alto Reseach Center Incorporated
• Xerox Corp

Inventors

• Chintapalli Mahati
• Garner Sean
• Pattekar Ashish
• Plochowietz Anne

Classifications

• B22F10/14 Primary

  by jetting of binder onto a bed of metal powder · CPC title

• B22F1/10

  Metallic powder containing lubricating or binding agents; Metallic powder containing organic material · CPC title

• B22F10/66

  by mechanical means · CPC title

• B22F12/50

  Means for feeding of material, e.g. heads · CPC title

• B22F12/86

  Serial processing with multiple devices grouped · CPC title