Rapid Temperature Control in Melt Extrusion Additive Manufacturing Using Induction Heated Lightweight Nozzle

Abstract

An approach for improving and maintaining consistent fusion quality of the deposited material during FDM 3d-printing is proposed. This approach is based on the nozzle temperature control during the printing process to adjust the polymer extrusion temperature with a speed and accuracy adequate to the FDM process. High frequency induction heating of the lightweight nozzle (<1 g) was used. To control the temperature of a lightweight nozzle, the resonant temperature measurement method based on the analysis of the high frequency eddy currents is proposed. To determine the parameters of the nozzle and the inductor as a plant, a FEM model of the inductive heating of the nozzle and a simulated model of a serial-parallel resonant circuit containing inductor were developed. Linearization of the automatic control system was performed to ensure the equal quality of regulation when operating in a wide temperature range. The quality of regulation, stability of the system, and coefficients of the PID controller were evaluated using a simulated model of the control system. A number of test samples were printed from various materials, and tensile stress testing was carried out. The developed control method reduces the nozzle temperature control error from 20 to 0.2 °C and decreases control delay by more than six times.