Additive manufacturing for an overhang

Abstract

In one example, a non-transitory processor readable medium with instructions thereon that when executed cause an additive manufacturing machine to inhibit build material from coalescing in an area of a first layer of build material where a second slice of an object will overhang a first slice of the object formed in the first layer of build material.

1 - 15 . (canceled) 
     
     
         16 . An additive manufacturing process, comprising:
 forming a first layer of build material;   dispensing a liquid, light absorbing coalescing agent on to build material in the first layer in a pattern of a first slice of an object;   dispensing a liquid coalescence modifier agent on to build material in the first layer covering an overhang area where a second slice of the object will overhang the first slice;   exposing build material in the first layer patterned with coalescing agent to light to generate heat to melt patterned build material in the first layer;   forming a second layer of build material on the first layer of build material;   dispensing the liquid, light absorbing coalescing agent on to build material in the second layer, including the overhang area, in a pattern of the second slice; and   exposing build material in the second layer patterned with coalescing agent to light to generate heat to melt patterned build material.   
     
     
         17 . The process of  claim 16 , comprising, before exposing build material in the second layer patterned with coalescing agent to light to generate heat to melt patterned build material, dispensing coalescence modifier agent on to build material in the second layer along an edge of the overhang area. 
     
     
         18 . A non-transitory processor readable medium having instructions thereon that when executed cause an additive manufacturing machine to:
 form a first layer of build material;   dispense a liquid, light absorbing coalescing agent on to build material in the first layer in a pattern of a first slice of an object;   dispense a liquid coalescence modifier agent on to build material in the first layer covering an overhang area where a second slice of the object will overhang the first slice;   expose build material in the first layer patterned with coalescing agent to light to generate heat to melt patterned build material in the first layer;   form a second layer of build material on the first layer of build material;   dispense the liquid, light absorbing coalescing agent on to build material in the second layer, including the overhang area, in a pattern of the second slice; and   expose build material in the second layer patterned with coalescing agent to light to generate heat to melt patterned build material.   
     
     
         19 . The processor readable medium of  claim 16 , having instructions thereon to, before exposing build material in the second layer patterned with coalescing agent to light to generate heat to melt patterned build material, dispensing coalescence modifier agent on to build material in the second layer along an edge of the overhang area. 
     
     
         20 . A computer program product that includes the processor readable medium of  claim 18 . 
     
     
         21 . An additive manufacturing machine controller that includes the processor readable medium of  claim 18 . 
     
     
         22 . An additive manufacturing machine, comprising:
 a first device to layer powdered build material;   a second device to dispense a liquid, light absorbing coalescing agent on to build material;   a third device to dispense a liquid coalescence modifier agent on to build material;   a light source to apply light energy to build material; and   a controller to execute instructions to:   cause the first device to layer build material in a first layer;   cause the second device to dispense the coalescing agent on to build material in the first layer in a first pattern of a first slice of an object;   cause the third device to dispense the coalescence modifier agent on to build material in the first layer in an overhang area where a second slice of the object will overhang the first slice;   cause the light source to apply light energy to build material in the first layer patterned with coalescing agent to generate heat to melt patterned build material in the first layer;   cause the first device to layer build material in a second layer on the first layer;   cause the second device to dispense the coalescing agent on to build material in the second layer, including the overhang area, in a pattern of the second slice; and   cause the light source to apply light energy to build material in the second layer patterned with coalescing agent to generate heat to melt patterned build material in the second layer.   
     
     
         23 . The machine of  claim 22 , wherein the controller is to execute instructions to cause the third device to, before causing the light source to apply light energy to build material in the second layer, dispense the coalescence modifier agent on to build material in the second layer along an edge of the overhang area.