Extrusion-based additive manufacturing: 3d printing system and method

A method 4 of improved control of a temperature of an extrudate that is extruded using an extrusion-based additive manufacturing three-dimensional printing system, the printing system comprising:

• a printhead assembly comprising a feedstock liquefying unit and a heating element, the feedstock liquefying unit comprising:
• a liquefying portion that is arranged in thermal contact with the heating element, the heating element being configured to generate heat for transforming solid feedstock material received in the liquefying portion into liquefied feedstock material;
• an outlet portion that is connected to the liquefying portion for receiving liquefied feedstock material from the liquefying portion, the outlet portion being provided with a nozzle that is configured to extrude the liquefied feedstock material as an extrudate;
• an extrudate temperature sensor that is configured and arranged with respect to the nozzle for determining a temperature of the extrudate freshly exiting the nozzle;
• and
• a control unit that is operatively connected with the extrudate temperature sensor and the heating element, the control unit being configured to receive input including a predefined setpoint value for the temperature of the extrudate;
• execute a heater controlling algorithm that is configured to generate control settings for the heating element on the basis of the received input;
• determine a temperature offset between the predefined setpoint value for the temperature of the extrudate and the temperature of the extrudate received from the extrudate temperature sensor;
• and
• execute the heater controlling algorithm that is configured to generate adjusted control settings for the heating element based on said temperature offset in order to at least minimize said temperature offset;
• wherein the method comprises the steps of:
• operating the control unit to execute a heater controlling algorithm for generating control settings for the heating element on the basis of the received input;
• operating the extrudate temperature sensor to determine the temperature of the extrudate freshly exiting the nozzle while the printhead assembly is positioned at a non-printing location;
• operating the control unit to determine the temperature offset between the predefined setpoint value for the temperature of the extrudate and the determined temperature of the extrudate freshly exiting the nozzle;
• and
• operating the control unit to execute the heater controlling algorithm for generating adjusted control settings for the heating element based on said temperature offset in order to at least minimize said temperature offset.