Additive fabrication using variable build material feed rates

1. A method for feeding build material into and extruding build material out from a nozzle of a three-dimensional printer to fabricate an object, the object having an interior geometry and an exterior geometry, based on a computerized model of geometry of the object, the three-dimensional printer also comprising a build plate, the nozzle having an inlet and an outlet, the method comprising:

a. feeding the build material into the inlet according to a predetermined feed rate profile, which predetermined feed rate profile can be broken up into blocks of time, some of which blocks of time relate to fabricating the interior geometry of the object and some of which blocks of time relate to fabricating the exterior geometry of the object, each block of time being represented by a FFT (fast Fourier transform), where the blocks of time that relate to fabricating the exterior geometry are represented by a FFT that has significant high frequency content;

b. extruding build material from the outlet;

c. simultaneously with the extruding step, moving the outlet along a build path relative to the build plate to fabricate the object on the build plate; and

d. the build material is a metal-containing-multi-phase (MCMP) type material, and wherein the build material has at least one solid phase and at least one liquid phase co-existing and has a working temperature range that includes a temperature for extruding the build material out from the outlet.

2. The method of claim 1 , wherein the predetermined feed rate profile comprises intervals of at least two different feed rates.

3. The method of claim 1 , wherein the blocks of time that relate to fabricating the exterior geometry are represented by an FFT that has significant content exceeding 1 Hz.

4. The method of claim 1 , wherein the predetermined feed rate profile comprises a periodic variation of at least two different feed rates.

5. A method for feeding build material into and extruding build material out from a nozzle of a three-dimensional printer to fabricate an object, based on a computerized model of geometry of the object, the three-dimensional printer also comprising a build plate, the nozzle having an inlet and an outlet, there also being a set of feed rate profiles operational to print the object according to the computerized model, and a range of feed rates suitable for steady state extrusion, the method comprising:

a. feeding the build material into the inlet according to a combination of:

i. the set of feed rate profiles operational to print the object according to the computerized model; and

ii. a predetermined feed rate profile, which predetermined rate profile comprises at least two different feed rates, one being a high feed rate that exceeds the range of feed rates suitable for steady state extrusion;

b. extruding build material from the outlet;

c. simultaneously with the extruding step, moving the outlet along a build path relative to the build plate to fabricate the object on the build plate; and

d. the build material is a metal-containing-multi-phase (MCMP) type material, and wherein the build material has at least one solid phase and at least one liquid phase co-existing and wherein the build material has a working temperature range that includes a temperature for extruding the build material out from the outlet.

6. The method of claim 5 , wherein one of the at least two different feed rates is a low feed rate that is less than and outside the range of feed rates suitable for steady state extrusion.

7. The method of claim 5 , wherein one of the at least two different feed rates is a reverse feed rate.

8. The method of claim 5 , wherein one of the at least two different feed rates is a zero feed rate.

9. The method of claim 5 , wherein the predetermined rate profile comprises a periodic variation of at least two different feed rates.

10. The method of claim 5 , wherein a combined feed rate profile resulting from combining the set of feed rate profiles operational to print the object according to the computerized model and the predetermined feed rate profile, exhibits a time-averaged feed rate, which is within the range of feed rates suitable for steady state extrusion.

11. The method of claim 5 , wherein the predetermined feed rate profile comprises a feed rate profile related only to mitigation of clogs and other flow interruptions.

12. A method for feeding build material into and extruding build material out from a nozzle of a three-dimensional printer to fabricate an object, based on a computerized model of geometry of the object, the three-dimensional printer also comprising a build plate, the nozzle having an inlet and an outlet, there also being a set of feed rate profiles operational to print the object according to the computerized model, the method comprising:

a. feeding the build material into the inlet according to a combination of feed rates:

i. the set of feed rate profiles operational to print the object according to the computerized model; and

ii. a predetermined feed rate profile, which predetermined rate profile comprises at least two different feed rates;

b. extruding build material from the outlet;

c. simultaneously with the extruding step, moving the outlet along a build path relative to the build plate to fabricate the object on the build plate; and

d. the build material is a metal-containing-multi-phase (MCMP) type material, and wherein the build material has at least one solid phase and at least one liquid phase co-existing and wherein the build material has a working temperature range that includes a temperature for extruding the build material out from the outlet.

13. The method of claim 12 , further comprising applying a fixed-ratio-of-rates requirement to a ratio of the combination of feed rates and motion of the outlet along the build path.

14. The method of claim 12 , wherein the predetermined feed rate profile comprises a feed rate profile related only to mitigation of clogs and other flow interruptions.