HIGH SPEED EXTRUSION 3-D PRINTING SYSTEM
A three-dimensional printer and a method of printing includes feeding a feedstock into a print nozzle including a heated barrel by applying a first extrusion force on the feedstock with a feed system; heating the feedstock in the heated barrel at a first temperature to melt the feedstock; and depositing the melted feedstock onto a support table, wherein the first extrusion force and first temperature are selected to provide a volumetric flow rate in the range of up to 120 cubic millimeters per second.
1 . A method of printing with a 3D printer, comprising:
feeding a feedstock into a barrel by applying a first extrusion force;
heating the feedstock in the barrel at a first temperature; and
depositing the melted feedstock onto a support table, wherein the first extrusion force and first temperature are selected to cause the feedstock to undergo shear thinning.
2 . The method of claim 1 , further comprising melting the feedstock in a liquefier portion of the barrel, wherein a temperature of the barrel is in the range of 20° C. to 600° C.
3 . The method of claim 1 , wherein the feedstock is a filament and the method further comprises engaging the filament with a rotatable feed hob coupled to a drive motor to feed the filament into the barrel.
4 . The method of claim 1 , further comprising adjusting the first temperature and the first extrusion force to maintain shear thinning of the feedstock while printing.
5 . The method of claim 3 , further comprising measuring a torque applied to a drive shaft, wherein the rotatable feed hob is coupled to the drive motor by the drive shaft.
6 . The method of claim 5 , further comprising measuring torque by measuring a current supplied to the drive motor.
7 . The method of claim 1 , further comprising selecting the first extrusion force and the first temperature from a master viscosity curve, wherein the master viscosity curve is calculated from a plurality of viscosity measurements derived from a plurality of sensor measurements taken at various feed rates and various barrel temperatures.
8 . The method of claim 7 , wherein the sensor measurements include an extrusion force measurement, an encoder measurement, and a temperature sensor measurement.
9 . The method of claim 1 , further comprising reducing the first temperature of the barrel to a second temperature at a rate in the range of 0.5° C. per second to 60° C. per second.
10 . The method of claim 1 , further comprising stopping deposition of the melted feedstock by reducing the first extrusion force.
11 . A three-dimensional printer, comprising:
a control system;
a barrel including a heating element electrically coupled to the control system, wherein the control system is configured to select a barrel temperature and to heat the barrel with the heating element;
a feed system coupled to the control system configured to supply a feedstock to the barrel, wherein the control system is configured to select an extrusion force applied to the feedstock by the feed system; and
wherein the control system is configured to select a barrel temperature and an extrusion force that causes the feedstock to undergo shear thinning during printing.
12 . The three-dimensional printer of claim 11 , wherein the feed system comprises: a drive motor including a drive shaft; a feed hob coupled to the drive shaft and configured to engage the feedstock; a torque sensor electrically coupled to the control system configured to measure extrusion force applied by the drive motor; and an encoder electrically coupled to the control system configured to measure a speed of the drive shaft.
13 . The three-dimensional printer of claim 12 , wherein a temperature sensor is affixed to the barrel and coupled to the control system.
14 . The three-dimensional printer of claim 13 , wherein the control system is configured to calculate a master curve based on a plurality of viscosity measurements derived from extruding the feedstock at various feed rates, wherein the various feed rates are measured by the encoder, temperatures measured by the temperature sensor; and the extrusion force for each feed rate and each temperature measured by the torque sensor.
15 . The three-dimensional printer of claim 14 , wherein the torque sensor is a current sensor configured to measure a current applied to the drive motor.
16 . The three-dimensional printer of claim 11 , further comprising a cooling system.
17 . A method of calibrating a three-dimensional printer, comprising:
performing a feedstock feed rate sweep by extruding a feedstock material through a printer nozzle at various extrusion forces and barrel temperatures to achieve a range of feed rates;
deriving a feedstock viscosity at each feed rate and barrel temperature;
calculating a master viscosity curve for the feedstock from the feedstock viscosity derived at each feed rate and each barrel temperature; and
selecting a feed rate and temperature range for the feedstock for providing a maximum feedstock throughput rate.
18 . The method of claim 17 , wherein each feed rate is measured by an encoder configured to measure the rotational rate of a drive shaft.
19 . The method of claim 18 , wherein each extrusion force is measured by a torque sensor associated with a drive motor coupled to the drive shaft.
20 . The method of claim 17 , wherein each barrel temperature is measured by a temperature sensor mounted to the barrel.