Experimental study of the features of the kerf generated by a 200 A high tolerance plasma arc cutting system

In this study a 200 A high tolerance plasma arc cutting (HTPAC) system is utilised to cut plates from 15 mm thick mild steel sheets metals. The Design of Experiments (DoE) technique is used in order to outline the main parameters which define the geometry of the cut profile, as well as its constancy (i.e. stability). Beyond arc voltage and cutting speed, plasma gas flow rate, shield gas flow rate and shield gas composition are included in the analysis and their effects on kerf position and shape are evaluated. The performed analysis indicates that cutting speed and arc voltage affect the kerf formation mechanism and their interaction is also important in defining the inclination of the cut. Despite the value selected for these parameters, the analysis shows that plates can have different profiles, depending on the specific side considered. Therefore, this effect has to be taken into account when designing workpieces to be cut with this technology. Eventually, the present paper points out that high quality parts (unevenness class 2, according to ISO9013) can be obtained as a result of an experimental investigation aimed at selecting the proper values of process parameters. Therefore, the type of experimental study proposed in this paper can be applied in different operating condition (i.e. material and thickness of interest) in order to obtain the best performance from the HTPAC system.