Effect of Surface Degradation of Actuator on Electromagnetic Pulse Welding

Abstract

One of the high speed welding process among all the present welding techniques is Electromagnetic pulse welding (EMPW). Electromagnetic force from discharged current through Actuator responsible to develop a repulsive force between the induced current flowing parallel and in opposite direction. For successful weldment using this process the design of actuator is the most important factor due to high magnetic field on surface of work piece. In case of high quality welding factors such as impact velocity, impact angle standoff distance, flyer thickness and overlap length have to be chosen carefully. Still the surface of actuators plays vital role over all those above mentioned factors. EMPW has wide applications in nuclear industry, automotive industry, aerospace, electrical industries. However major issues such as formability and weldability still remain due to surface degradation. Surface degradation affects the magnetic field on surface of work piece. Due to ease in controlling the magnetic field enveloped inside tubes, the EMPW has been widely used for tube welding. In case of flat components control of magnetic field is difficult. Hence the application of EMPW gets restricted. But both tube and flat welding methods face same actuator surface degradation. The present work attempts to make a novel contribution by investigating the root cause of surface degradation and its elimination to improve welding quality in EMPW. The work emphasizes the approaches and engineering calculations required to effectively use of actuator in EMPW.