High Speed Imaging of Pilot Arcing and Piercing in Plasma Arc Cutting

High speed camera (HSC) imaging has been used to investigate pilot arcing and piercing process phases in plasma arc cutting of mild steel (MS) and stainless steel (SS) plates with dual gas torches in various operating conditions, providing new insight of the process and highlighting some interesting phenomena. For pilot arcing, HSC imaging has been used to estimate the influence of different operative parameters (arc current, plasma pressure and swirl strength) on the shape of pilot arc and on the type rotational motion of the pilot arc loop attachment on the nozzle tip, to describe the behaviour of the arc and of the emissive surface during different phases of pilot arcing and to track trajectories and velocities of hafnium particles emitted from the electrode during that phase. As regards the piercing process phases, HSC imaging allowed to study phenomena that take place during double arcing and the arc behaviour during piercing of SS thick plates.