Statistical modelling and analysis of material removal rate and surface roughness during wire electrical discharge hybrid turning (WEDHT) process

Abstract

The non-traditional machining process is highly recommended for machining difficult-to-cut materials with increased hardness, toughness, work hardening effect, and poor thermal diffusivity, etc. Wire electrical discharge machining (Wire-EDM) is one of the above said processes used to machine material which are electrically conductive. One of the variants of Wire-EDM process is wire electrical discharge hybrid turning (WEDHT) process, in which, the work material is made to rotate during material removal resulting in cylindrical components manufacturing. This process follows the principle of sparking and erosion for material removal with moving wire as a tool electrode. In the present study, WEDHT process is performed on Ti-6Al-4V alloy, which has applications in the areas of biomedical, marine, chemical, aerospace, etc. 27 experiments are performed using diffusion annealed zinc coated brass wire as the tool electrode by varying servo feed, pulse ON time and wire feed rate at three different levels to study the surface quality and material removal as the output performances. Atomic force microscopy (AFM) technique gives a 3D profile of the machined surface and measures the surface roughness. These measured 3D results are validated once again in 2D surface profile meter. The factor effects of all three input parameters are analyzed individually and analysis of variance (ANOVA) for all the performance responses are studied to know the most contributing factor in deciding the surface roughness (SR) and material removal, respectively. The regression analysis is performed for the response measures and the model parameters are analysed for goodness of fit using residual plot. Pulse ON time contributes more in deciding the SR and material removal rate (MRR) of the component followed by servo feed and wire feed rate. The interaction effects of the parameters are found to be insignificant.