Accuracy improvement and surface finishing using fusing agent and detailing agent

1. An additive manufacturing system comprising:

a build material supply mechanism;

a printhead;

an energy source; and

a controller configured to:

control the build material supply mechanism to form a layer of build material;

control the print head to:

apply fusing agent and not apply detailing agent to a first region of the layer, the first region corresponding to an inner region of an object undergoing additive manufacture;

apply a varying amount of fusing agent and a varying amount of detailing agent to a second region of the layer contiguous with the first region, the second region corresponding to a middle region of the object, wherein the varying amount of fusing agent applied across the second region is a randomly varying amount of fusing agent and/or the varying amount of detailing agent applied across the second region is a randomly varying amount of detailing agent; and

apply detailing agent and not apply fusing agent to a third region of the layer contiguous with the second region and not contiguous with the first region, the third region corresponding to an outer region of the object; and

control the energy source to apply fusing energy to the layer.

2. An additive manufacturing system according to claim 1 , wherein:

the varying amount of fusing agent applied across the second region is a randomly varying amount of fusing agent.

3. An additive manufacturing system according to claim 1 , wherein:

the varying amount of detailing agent applied across the second region is a randomly varying amount of detailing agent.

4. An additive manufacturing system according to claim 1 , wherein the controller is configured to control the print head to apply a varying amount of detailing agent across the third region.

5. An additive manufacturing system according to claim 4 , wherein the amount of detailing agent applied across the third region is a randomly varying amount of detailing agent.

6. An additive manufacturing system according to claim 1 , wherein the controller is configured to control the print head to simultaneously apply fusing agent and detailing agent to the second region.

7. A method of additive manufacturing, the method comprising:

generating print data to cause:

application of fusing agent and not detailing agent to a first region of a layer of build material of an object undergoing additive manufacturing, the first region corresponding to an inner region of an object undergoing additive manufacturing;

application of fusing agent and detailing agent to a second region of the layer, the second layer corresponding to a middle region of the object, including:

application of an amount of fusing agent and/or detailing agent that varies randomly across the second region; or

application of an amount of fusing agent that varies smoothly across the second region from a greater amount near the first region to a lesser amount near the third region and/or application of an amount of detailing agent that varies smoothly across the second region from a lesser amount near the first region to a greater amount near the third region; and

application of detailing agent to a third region of the layer, the third region corresponding to an outer layer of the object.

8. A method according to claim 7 , wherein generating print data comprises:

receiving data defining an object to be printed; and

modifying the received data to generate the print data.

9. A method according to claim 7 , comprising:

applying fusing energy to fuse the first region more than the second region; and

applying fusing energy to fuse the second region more than the third region.

10. A method according to claim 7 , comprising removing an exterior portion of the object.

11. A method according to claim 10 , wherein removing the exterior portion of the object comprises completely removing the third region of the layer.

12. A method according to claim 10 , wherein removing the exterior portion of the object comprises partially removing the second region of the layer.

13. A method according to claim 10 , wherein removing the exterior portion of the object comprises one or more of sandblasting and applying compressed air.

14. A method according to claim 7 , wherein the application of fusing agent and detailing agent to the second region of the layer includes application of an amount of fusing agent that varies randomly across the second region and application of an amount of detailing agent that varies randomly across the second region.

15. A method according to claim 7 , wherein the application of fusing agent and detailing agent to the second region of the layer includes application of an amount of fusing agent that varies smoothly across the second region from a greater amount near the first region to a lesser amount near the third region and application of an amount of detailing agent that varies smoothly across the second region from a lesser amount near the first region to a greater amount near the third region.

16. A non-transitory computer readable medium having computer readable instructions thereon that, when executed, generate print data that causes an additive manufacturing system to perform the method of claim 7 .

17. An additive manufacturing system controller that includes the computer readable medium of claim 16 .

18. A non-transitory computer-readable storage medium having computer-readable instructions thereon which, when executed, generate print data that causes an additive manufacturing system to:

apply fusing agent but not detailing agent to a first region of a layer of build material, the first region corresponding to an inner region of an object undergoing additive manufacture;

apply fusing agent and detailing agent to a second region of the layer contiguous with the first region, the second region corresponding to a middle region of the object;

apply detailing agent but not fusing agent to a third region of the layer contiguous with the second region and not contiguous with the first region, the third region corresponding to an outer region of the object; and

apply fusing energy to the layer to completely fuse the first region and partially fuse the second region, wherein the controller is configured to control the print head to:

apply fusing agent across the second region in an amount that varies from a greater amount near the first region and a lesser amount near the third region; and

apply detailing agent across the second region in an amount that varies from a lesser amount near the first region and a greater amount near the third region.

19. An additive manufacturing system according to claim 18 , wherein:

the lesser amount of fusing agent is 0 and the amount of fusing agent applied across the second region varies smoothly from the greater amount to the lesser amount; and

the lesser amount of detailing agent is 0 and the amount of detailing agent applied across the second region varies smoothly from the lesser amount to the greater amount.

20. An additive manufacturing system controller that includes the computer readable medium of claim 18 .