Fractal-based analysis of the influence of current intensity on surface hardness and surface roughness of Steel workpiece in Electrical Discharge process

Smoothness of the machined surface is an important feature in machining. Fractal geometry is a creative and practical branch of modern mathematics. One of the most important features of fractal fractal geometry is the fractal dimension. The purpose of this study is to investigate the effect of current intensity on the surface hardness and roughness of steel workpiece in the process of electric discharge using fractal analysis. For this purpose, parts of alloy steel AISI316 L were machined by Spark. Then, the samples were imaged microscopically to evaluate the quality of the machined surfaces by scanning electron microscopy (SEM). The results of experiments and fractal analysis showed that with 10 times increase in current intensity, average surface roughness increased about twice and surface hardness decreases 0.8 times.Also, increasing current intensities increased the standard and amplitude of surface signal while, the frequency of changes is decreased. This indicates that the level and height of the surface are increased and points of higher altitude and depth are created at the surface which means that the surface has become rougher. As a result, increasing the surface roughness and reducing the surface hardness of the workpiece has increased the fractal dimension of machining surfaces.