Open-source modular resistance welding equipment for thermoplastic composites

This paper presents an integrated open-source platform for resistance welding of thermoplastic composites, developed as a low-cost, self-contained alternative to expensive industrial welding stations. The system combines automated pressure control, real-time instrumentation, and automated data logging within a modular hardware architecture consisting of an aluminum frame and an electrically insulating wooden base that minimizes current leakage, complemented during operation by external ceramic insulator plates, not a permanent component of the equipment, positioned at the sample-electrode interface, where they act as the thermal barrier at the joint and protect the wooden structure from direct exposure to weld interface temperatures. Pressure is regulated through a closed-loop feedback system using an Arduino-controlled linear actuator and load cell. A dedicated Python-based graphical user interface provides high-fidelity process control and monitoring, featuring real-time visualization of voltage versus time, continuous acquisition of temperature (Type-K thermocouple), voltage, current, and power, and on-the-fly calculation of power density and heating element resistance. Power is supplied by a Huawei R4850G2 rectifier and JUNTEK DPM8624 converter, fully integrated into the control logic. At the end of each welding cycle, the software automatically generates a comprehensive PDF report (including process parameters, specimen dimensions, and the voltage-time graph) and a synchronized raw data log file (.txt) containing voltage, current, power, pressure, and temperature sampled every second. The platform enables precise, repeatable weld quality and accessible data acquisition for research and small-scale manufacturing of thermoplastic composite joints.