Characteristics of a Co₂ Shielded Gas Tungsten Arc

In order to develop a novel heat source for materials processing with low costs and high productivity in comparison with the TIG arc, the characteristics of a CO₂ gas shielded plasma arc are studied. A double gas shielded system which consists of CO₂ gas and inert gas is employed for the plasma arc torch, so avoiding the consumption of tungsten electrode, and then achieves equivalent arc stability to a TIG arc for 1800 seconds operation. The arc voltage of the CO₂ gas shielded plasma arc in the conditions of arc current 150 A and arc gap 3 mm is about 19 V, which is much higher than the 12 V of a TIG arc. The CO₂ gas clearly constricts the arc and the maximum heat intensity at the anode surface in the CO₂ gas shielded plasma arc becomes about 10 times larger than that of the TIG arc. The penetration depth of stainless steel melted by the CO₂ gas shielded plasma arc is much larger than that for the argon TIG arc. It is concluded that the greater heating power of the CO₂ gas shielded plasma arc due to the arc constriction remarkably contributes to the high productivity of materials processing