Cutting and Shield Gases Pressure Effects on Plasma Cutting Quality

In this paper, the effects of the shield gas on cut quality in plasma arc cutting were quantified experimentally. Measurements were performed on plasma arc cutting kerfs (PACs) cut through a 4 mm (1/8 in.) S355 steel plates with a Gys Neocut105 cutter equipped with a Toparc AT-125 torch. This system uses compressed air as both cutting and shield gas. Separate circuits for shielding air and cutting air were used. This way, the influences of the shield air and the cutting air could be studied independently. A full 3-factor, 3-level Taguchi design was followed. The studied factors are the cutting air pressure, the shield air pressure, and the arc current. The measured responses are the removed steel surface and the right and left bevel angles. As expected, the current proved to have the greatest influence on the kerf surface. The cutting air pressure significantly influenced the kerfs’ shapes while the shield air flow rate proved less important yet sensitive. Some negative bevel angles at high plasma, high cutting, and high shield air pressures have also been observed.