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 metallurgy material containing a powdered material for forming the object and a binder system including one or more binders to resist deformation of a net shape of the object during processing of the object into a final part;   a second extruder coupled to a second source of an interface material for fabricating an interface layer between the object and an adjacent surface of a support structure, wherein the interface material resists bonding of the object to the support structure during sintering of the object into the final part;   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 the support structure from the build material, fabricate the interface layer from the interface material, and fabricate a surface of the object adjacent to the interface layer from the build material.   
     
     
         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  where in the powdered metallurgy material includes a sinterable material. 
     
     
         5 . The printer of  claim 1  wherein the build material includes an infiltrable powder. 
     
     
         6 . 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. 
     
     
         7 . The printer of  claim 1  wherein the binder system includes at least one polymer.