Progress in oxyfuel cutting automation using ion current sensing

This paper describes recent advances in the use of ion currents as a sensing method in the oxyfuel cutting torch preheat flame. The flame exhibits semiconductor characteristics at signal-level voltages (± 10 V) that can be leveraged to monitor important attributes of the process: standoff distance, ready-to-pierce, pierce initiation success, pierce complete, cut health, and fuel/oxygen mixture. This work provides a concise introduction to ion currents, describes what is currently understood about the oxyfuel flame’s electrical characteristics, presents data describing their use as a sensor, makes recommendations for their adoption in a practical system, and poses important questions that require further attention.