Printer with dual extruders for fabricating removable supports

Abstract

Support structures are used in certain additive fabrication processes to permit fabrication of a greater range of object geometries. For additive fabrication processes with materials that are subsequently sintered into a final part, a printer is configured to further fabricate an interface layer between the object and the support structure in order to inhibit bonding between adjacent surfaces of the support structure and the object during sintering.

What is claimed is: 
     
         1 . A printer for three-dimensional fabrication, the printer comprising:
 a build plate;   a first extruder coupled to a first source of a build material for fabricating an object, the build material including a powdered material for forming the object and a binder system including one or more binders that resist deformation of a net shape of the build material extruded from the first extruder during processing of the net shape into a final part;   a second extruder coupled to a second source of an interface material for fabricating an interface layer, wherein the interface material resists bonding of the build material to adjacent surfaces during sintering, and wherein the interface material reduces to a powder and resists bonding of the build material to adjacent surfaces during sintering of the build material;   a robotic system operable to move the first extruder and the second extruder relative to the build plate; and   a processor configured by computer executable code to move the robotic system along a build path relative to the build plate while extruding from at least one of the first extruder and the second extruder to: fabricate a first object from the build material, apply an interface layer to a first surface of the first object, and fabricate a second surface of a second object from the build material at a location adjacent to the interface layer and opposing the first surface of the first object, wherein the second object is structurally independent from and mechanically related to the first object.   
     
     
         2 . The printer of  claim 1  wherein the interface material includes a ceramic powder. 
     
     
         3 . The printer of  claim 1  wherein the build material includes a metal powder. 
     
     
         4 . The printer of  claim 1  wherein the build material includes an infiltrable powder. 
     
     
         5 . The printer of  claim 1  wherein the binder system includes a first binder that resists deformation of the net shape during debinding of the object and a second binder that resists deformation of the net shape during a beginning of a thermal sintering cycle for the object. 
     
     
         6 . The printer of  claim 1  wherein the binder system includes at least one polymer.