Abstract
Air plasma cutting technology is widely used for cutting complex profiles, geometrics, shapes, and sections in electrically conducting materials at high speed. In this experimental research, oxygen was introduced along with compressed air during plasma air cutting of 10 mm thick C-20 carbon steel plates and their effect on cut surface quality was studied. A total of twenty experiments with compressed air were performed using a full-factorial design of experiments to identify the optimum ranges of process parameters. Further, based on the obtained results from preliminary experiments, twenty experiments were designed using a central composite design (CCD) approach of response surface method (RSM) using compressed air and a mixture of compressed air and oxygen. The cut surface quality was analysed for both conditions in terms of kerf width, dross height, bevel angle, surface roughness, maximum cutting temperature and heat-affected zone (HAZ). A comparative study between compressed air plasma cutting and oxygen assisted compressed air plasma cutting reveals that the addition of oxygen with compressed air improves the arc quality of plasma, which consequently reduced cutting time, kerf width, dross height, and surface roughness of the work materials. The microstructure study of both the cut surfaces reveals that the addition of oxygen with compressed air reduced the length of HAZ significantly compared to compressed air plasma cutting. The outcome of this study would be beneficial for the researcher and engineers working in the area of plasma-assisted cutting of metals.