Oxygen plasma arc cutting (PAC) is widely used in various industrial fields. In case of cutting magnetized plates, the magnetic field is concentrated around the cutting front according to the progress of the cutting, and the electromagnetic force induced by leakage magnetic field deflects the plasma jet. The deflected plasma jet causes poor cutting quality and sometimes makes fatal damages on the electrode and the nozzle by double arc as abnormal discharge. This phenomenon is called Magnetic Arc Blow and it is critical issue of applying plasma cutting on magnetized plate. The purpose of this study is to investigate the arc blow behavior and to devise a method to prevent it.
We examined the relationship between operating conditions and double arc with external magnetic fields on the plasma jet. We found out criteria of operation conditions that induces the arc blow. In addition, we have succeeded to suppress the double arc generation attributed to the external magnetic field with a mild steel shield cap attachment around the nozzle tip.
