Shrinkable support structures

Patent metadata

Field	Value
Publication number	US-2018154440-A1
Application number	US-201815868481-A
Country	US
Kind code	A1
Filing date	Jan 11, 2018
Priority date	Apr 14, 2016
Publication date	Jun 7, 2018
Grant date	—

Abstract

A variety of additive manufacturing techniques can be adapted to fabricate a substantially net shape object from a computerized model using materials that can be debound and sintered into a fully dense metallic part or the like. However, during sintering, the net shape will shrink as binder escapes and the base material fuses into a dense final part. If the foundation beneath the object does not shrink in a corresponding fashion, the resulting stresses throughout the object can lead to fracturing, warping or other physical damage to the object resulting in a failed fabrication. To address this issue, a variety of techniques are disclosed for substrates and build plates that contract in a manner complementary to the object during debinding and sintering.

First claim

What is claimed is:

1 . A method comprising:
providing a support structure; and fabricating an object from a build material on the support structure, wherein the object has a net shape based on a computerized model, wherein the build material includes a powdered material for forming a final part and a binder system including one or more binders, wherein the one or more binders resist deformation of the object during a fabrication, a debinding, and a sintering of the object into the final part, and wherein the support structure is configured to match a shrinkage of the object during at least one of the debinding and the sintering.

2 . The method of claim 1 further comprising fabricating the support structure on a build plate formed of a material that is debindable and sinterable.

3 . The method of claim 1 further comprising fabricating a build plate for use as the support structure by injection molding the build plate with a second material having at least one of a debind shrinkage rate and a sintering shrinkage rate matching the build material.

4 . The method of claim 1 wherein providing the support structure includes fabricating a structural support for at least one of a bridge or an overhang in the object from a second material having at least one of a debind shrinkage rate and a sintering shrinkage rate matching the build material.

5 . The method of claim 1 wherein providing the support structure includes fabricating a substrate for the object from a second material having at least one of a debind shrinkage rate and a sintering shrinkage rate matching the build material.

6 . The method of claim 5 wherein the substrate includes two or more independent substrate plates coupled by a number of tie bars that move the independent substrate plates together at a rate corresponding to a shrinkage of the object during at least one of debind and sintering.

7 . The method of claim 5 wherein the object has two or more discrete and separate contact surfaces in a plane along a top surface of the substrate, wherein the substrate comprises two or more corresponding separate substrate regions formed about a projection of each of the two or more discrete and separate contact surfaces, the substrate further comprising at least one tie bar coupling the two or more discrete and separate contact surfaces to one another in order to facilitate a movement of the corresponding separate substrate regions in a manner geographically matched to a motion of the two or more discrete and separate contact surfaces during at least one of debind and shrinkage.

8 . The method of claim 5 wherein a shape of the substrate is based upon a convex hull of a projection of the object into a plane of a build plate that receives the object during fabrication.

9 . The method of claim 8 wherein the shape is a shell uniformly displaced by a predetermined offset from the convex hull of the projection.

10 . The method of claim 8 wherein the shape of the substrate includes an interior opening formed by a shell displaced by a second predetermined offset from an interior boundary of the projection.

11 . The method of claim 5 wherein the substrate includes a plurality of perforations through the substrate positioned to provide a drainage route through the substrate for a debind solvent.

12 . The method of claim 11 wherein the plurality of perforations extend from a top surface of the substrate to a bottom surface of the substrate within regions of the substrate where an adjacent layer of the object does not vertically cover the substrate.

13 . The method of claim 11 wherein the plurality of perforations extend from a top surface of the substrate to one or more side surfaces of the substrate.

14 . The method of claim 11 further comprising positioning the plurality of perforations in the substrate independently from a geometry of the object.

15 . The method of claim 11 wherein the plurality of perforations are positioned within a region of the substrate enclosed in an x-y plane of the substrate by a vertical wall of the object extending in a z-axis from a top surface of the substrate and surrounding the region of the substrate.

16 . The method of claim 5 wherein the substrate forms a continuous, closed surface below a projection of the object into a plane of a build plate that receives the object during fabrication.

17 . The method of claim 1 further comprising fabricating an interface layer between the support structure and the object that resists bonding of the support structure to the object during sintering.

18 . The method of claim 1 further comprising fabricating the support structure from a support material including a ceramic.

19 . The method of claim 1 further comprising fabricating the support structure from a support material including a ceramic powder in a second binder system.

20 . A system comprising:
a build plate; a supply of a build material, the build material including a powdered material for forming a final part and a binder system including one or more binders, wherein the one or more binders resist deformation of the build material during fabricating, debinding, and sintering of the build material into the final part; and an additive fabrication system configured to fabricate an object on the build plate from the build material, the additive fabrication system imparting a net shape to the build material based on a computerized model, wherein the additive fabrication system is configured to provide a build surface having a shrinkage rate matching at least one of a debind shrinkage rate and a sintering shrinkage rate of the build material.

21 . The system of claim 20 wherein the build surface includes a preformed substrate.

22 . The system of claim 20 wherein the build surface includes a shrinking substrate fabricated below a convex hull of a projection of the object into a plane of the build plate.

23 . The system of claim 20 further comprising a debinding station to remove at least one of the one or more binders from the build material in the object, and a sintering oven to heat the object to form bonds between particles of the powdered material.

24 . The system of claim 20 wherein the additive fabrication system includes at least one of a binder jet system or a fused filament fabrication system.

25 . A method comprising:
receiving an article including a support structure, an object fabricated from a build material on the support structure, wherein the build material includes a powdered material for forming a final part and a binder system including one or more binders, and an interface layer between the object and the support structure that resists bonding of the support structure to the object during sintering, wherein the one or more binders resist deformation of the object during a fabrication, a debinding, and a sintering of the object into the final part, and wherein the support structure is configured to match a shrinkage of the object during at least one of the debinding and the sintering; and processing the article to form the object into the final part, wherein processing includes at least one of debinding the article and sintering the article.

Assignees

• Desktop Metal Inc

Inventors

• Gibson Michael Andrew
• Myerberg Jonah Samuel
• Fulop Ricardo
• Chin Ricardo
• Verminski Matthew David
• Fontana Richard Remo
• Schuh Christopher Allan
• Chiang Yet-Ming
• Hart Anastasios John

Classifications

• B22F10/28

  Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM] · CPC title

• B22F10/62

  by chemical means · CPC title

• B22F10/40

  Structures for supporting workpieces or articles during manufacture and removed afterwards · CPC title

• B22F10/64

  by thermal means (control of energy beam parameters for post heating B22F10/364) · CPC title

• B22F10/12

  by photopolymerisation, e.g. stereolithography [SLA] or digital light processing [DLP] · CPC title