Driving technology and creating future solutions: experimental study of cutting two separate thin steel sheets simultaneously using plasma machining, parameters optimisation and response prediction

This research Paper investigates the ability of using plasma machining for cutting simultaneously two parallel thin layers at different gap distances. The main aim of this work is to identify whether this technology can be more appropriate than using a circular saw to process a three-dimensional structure material such as double layers, box sections or rails. This research is aimed at those working in the automotive industry. Test models were built for the experiments with 0.7mm thick sheets cold rolled steel deep drawing DCO1 grade which are used in the automotive industry. First, a series of cuts were carried out varying the plasma parameters mainly cutting speed, intensity, pressure, also we included the gap distance between the two sheets as an input variable, followed by an additional tests to optimise the process and minimise the deformation and heat affected zones (HAZ) on the top sheets by adopting the Taguchi method, specimens collected were quality assessed for Kerf, dross, hardness change, offset distance between the top and bottom cut edge, distortion and HAZ. A triple scan camera 3D ATOS was used to analyse the deformation and then the samples were mounted, polished and etched with 5% Nital acid before measuring the HAZ size with an optical microscope, all the data were gathered and displayed in the tables below. Results revealed that plasma could be an alternative tool if optimised but it is dependent on the tolerances and the quality required. Analyse of variance (ANOVA) showed that the input-controlled parameters which had the most influence on the top sheet distortion and HAZ were respectively intensity and gap. It was found that a mathematical model could be constructed to predict approximatively the response for both phenomenon. Cutting simultaneously a double layered structure using the plasma approach has never been explored in the past and was believed to be impossible, therefore the idea of this research was to fill the knowledge gap on whether the plasma technology was able to cut multi-layered parts and also look at the possibility of reusing the energy remaining after exiting the top layer to perform an additional cut through the neighbouring layer.