REMOVABLE SINTER SUPPORTS
Additive fabrication systems generally use support structures to expand the available range of features and geometries in fabricated objects. For example, when a vertical shelf or cantilever extends from an object, a supplemental support structure may be required to provide a surface that this feature can be fabricated upon. This process may become more difficult when a surface requiring support is enclosed within a cavity inside an object being fabricated. Techniques are disclosed herein for fabricating supports that can be removed from within cavities in an object.
1 . A method comprising:
fabricating an object from a build material using an additive fabrication process, the object having a cavity and a passageway, the cavity including an interior surface requiring support during fabrication and the passageway providing an open passage between the cavity and an exterior environment for the object;
fabricating a support structure for the interior surface, wherein the support structure includes a composite support structure formed from a plurality of independent support structures configured to collectively provide support to the interior surface to satisfy a fabrication rule for the build material, wherein the passageway is smaller than the composite support structure, and wherein each of the independent support structures is shaped and sized for individual removal from the cavity through the passageway; and
fabricating an interface layer between each of the plurality of independent support structures to facilitate disassembly and removal of each of the plurality of independent support structures from the cavity through the passageway.
2 . The method of claim 1 wherein the composite support structure has a shape with dimensions collectively too large to pass through a smallest width of the passageway.
3 . The method of claim 1 wherein the build material includes a powdered material and a binder system, the binder system including a first binder that resists deformation of a net shape of the object during fabrication and a second binder that resists deformation of the net shape of the object during sintering of the object into a final part.
4 . The method of claim 3 wherein the powdered material includes a metallic powder.
5 . The method of claim 1 wherein the interface layer is formed of an interface material including a ceramic powder.
6 . The method of claim 1 wherein the interface layer is formed of an interface material that resists bonding of the support structure to the interior surface of the object during sintering.
7 . The method of claim 1 further comprising fabricating a second interface layer between one of the plurality of independent support structures and an adjacent portion of the interior surface of the cavity.
8 . The method of claim 1 further comprising debinding the object.
9 . The method of claim 1 further comprising sintering the object.
10 . The method of claim 1 wherein the support structure is a fabrication support structure, and further wherein the interface layer is removable with a debind.
11 . The method of claim 10 further comprising removing the interface layer and removing the support structure after debinding and before sintering of the obj ect.
12 . The method of claim 1 wherein fabricating the object includes fabricating a plurality of passageways arranged to flush fluid in from a first one of the passageways through the cavity and out through a second one of the passageways.
13 - 20 . (canceled)
21 . A method comprising:
receiving an article including an object fabricated from a build material, the object having a cavity and a passageway, the cavity including an interior surface requiring support during fabrication and the passageway providing an open passage between the cavity and an exterior environment for the object, the article further including a support structure for the interior surface, wherein the support structure includes a composite support structure formed from a plurality of independent support structures configured to collectively provide support to the interior surface to satisfy a fabrication rule for the build material, wherein the passageway is smaller than the composite support structure, and wherein each of the independent support structures is shaped and sized for individual removal from the cavity through the passageway, the article further including an interface layer between each of the plurality of independent support structures to facilitate disassembly and removal of each of the plurality of independent support structures from the cavity through the passageway; and
processing the article into a final part, wherein processing includes at least one of debinding the article and sintering the article.
22 . (canceled)