Experimental Investigation of Tribological Aspects of Wire Electrical Discharge Machined Surface Concerning Surface Intigrity

Wire-electrical discharge machining (WEDM) is non-traditional machining process in which a pulsed voltage difference between a wire electrode and a conductive workpiece initiates sparks which erode workpiece material. Removing material in such way is often advantageous when the workpiece material would be difficult to machine with traditional machining tools due to high strength, hardness, toughness, etc. This process has been used in commercial machine tools for nearly half a century. It is well known that the EDM process has detrimental impact on the surface integrity of machined surfaces. Each spark melts a small portion of the workpiece. A portion of this molten material is ejected and flushed away. The remaining material re-solidifies to form a surface layer known as the recast layer. This layer can contain an altered microstructure, tensile stresses, micro cracks, impurities which can lead to premature part failure when put to service. Surface integrity effects are depends upon both the wire-EDM process parameters and the chemical composition of the wokpiece. Experimentation has been done using Tauchi’s L9 orthogonal array. Each experiment was conducted under different combinations of pulse on time, pulse off time and wire feed. The optimum machining parameter combination was obtained by using the analysis of signal-to-noise (S/N ) ratio, analysis of means and analysis of variance (ANOVA) in Minitab 15 Software. The analysis of variance (ANOVA) was carried out to study the effect of process parameters on process performance.