HEATER FOR THREE-DIMENSIONAL PRINTING

1 . A device comprising:

an extruder;

a thermal core in the extruder having a chamber for receiving and conducting a build material;

at least one heating element adjacent to the thermal core configured to generate enough heat to melt the build material in the thermal core;

an extrusion tip at one end of the extruder configured to direct the molten build material; and

a safety system integrated into the heating element to regulate the temperature and prevent the heating element from exceeding a predetermined operating temperature.

2 . The device of claim 1 wherein the safety system comprises a ceramic chip with a positive thermal coefficient (PTC).

3 . The device of claim 2 wherein the heating element has an operating range for the temperature in which the temperature can be controlled by controlling an applied voltage.

4 . The device of claim 3 wherein the heating element has an operating limit above which the temperature does not substantially increase with an increase in applied voltage.

5 . The device of claim 2 wherein the PTC element is configured to regulate the temperature at a maximum of 240° Celsius.

6 . The device of claim 3 wherein the operating range is about 0° to about 240° Celsius.

7 . The device of claim 4 wherein the operating limit is about 240° Celsius.

8 . The device of claim 1 further comprising a thermal barrier surrounding the extruder to retain heat within the thermal core.

9 . The device of claim 8 wherein the thermal barrier is formed of Polytetrafluoroethylene (PTFE).

10 . The device of claim 8 wherein the thermal barrier is formed of a ceramic.

11 . The device of claim 1 further comprising a three-dimensional printer wherein the extruder is configured within the three-dimensional printer.

12 . The device of claim 11 wherein the three-dimensional printer is a fused deposition modeling machine.

13 . An extruder for a three-dimensional printer comprising:

an opening to receive a build material;

a thermal core having a chamber to receive the build material;

a heating element near the thermal core to heat the build material into a liquid form, the heating element including a positive thermal coefficient (PTC) chip to regulate a temperature of the heating element to a predetermined threshold; and

an extrusion tip to extrude the liquid form of the build material.

14 . The extruder of claim 13 further comprising a power supply coupled to the heating element and configured to controllably provide power to the heating element.

15 . The extruder of claim 13 wherein the positive thermal coefficient chip is a ceramic chip.

16 . The extruder of claim 13 wherein the PTC chip has an operating range of about 0° to 240° Celsius.

17 . The device of claim 13 wherein the PTC chip has an operating limit of about 220° Celsius.

18 . The extruder of claim 13 wherein the PTC chip has an operating limit of about 240° Celsius.

19 . The extruder of claim 13 further comprising a plurality of heating elements, each formed of a PTC chip positioned near the thermal core.

20 . A device comprising:

an extruder;

a thermal core in the extruder having a chamber for receiving and conducting a build material;

at least one heating element adjacent to the thermal core configured to generate enough heat to melt the build material in the thermal core, the at least one heating element forming a removable and replaceable cartridge within the extruder;

an extrusion tip at one end of the extruder configured to direct the molten build material.

21 . The device of claim 20 wherein the at least one heating element includes a positive thermal coefficient (PTC) chip.

22 . The device of claim 21 further comprising a potting material to retain the removable and replaceable cartridge within the extruder.