Design of a Safety Interlock System Based on Safety Curtain Sensors for an Automated Soldering Machine

Abstract

The rapid advancement of automation technology has significantly improved productivity and product quality in the electronics manufacturing industry. Despite these advantages, automated soldering machines present potential safety hazards due to high-temperature soldering processes and moving mechanical components. Inadequate protection systems may expose operators to occupational accidents during machine operation. This study proposes the design of a safety interlock system based on a safety curtain sensor for an automated soldering machine. The proposed system integrates a safety curtain sensor, an Output Signal Switching Device (OSSD), a Panasonic FP-XH Programmable Logic Controller (PLC), and a safety relay to establish a fail-safe protection mechanism. During normal operation, the machine continues operating when the sensing area remains unobstructed. Conversely, when an operator or object enters the hazardous area, the safety curtain sensor detects the obstruction and transmits an OSSD signal to the PLC, which immediately activates the safety interlock to stop machine operation. The research methodology includes system design, hardware integration, PLC programming, wiring verification, and functional testing under both normal and abnormal operating conditions. The proposed system is expected to improve operator safety, reduce workplace accidents, and enhance the operational reliability of automated soldering machines without significantly affecting production efficiency.