Analysis and optimization of surface finish of wire electrical discharge machined miniature gears

Abstract

This article reports about analysis and optimization of surface roughness parameters (i.e. average roughness Ra and maximum roughness Rt) of wire electrical discharge machined fine-pitch miniature spur gears made of brass. Effects of four wire electrical discharge machining process parameters (i.e. voltage, pulse-on time, pulse-off time and wire feed rate) on the surface roughness parameters of the miniature gears were studied by conducting 29 experiments with two replicates each and designed based on Box–Behnken approach of response surface methodology. Analysis of variance study found all four input parameters to be significant. Experimentally, the surface roughness has been found to increase with higher voltage and longer pulse-on time and decrease with longer pulse-off time and higher wire feed rate. Desirability analysis was used to optimize the wire electrical discharge machining parameters, so as to minimize the Ra and Rt simultaneously. Optimum values of Ra and Rt obtained from the confirmation experiments conducted at the optimized wire electrical discharge machining parameters are superior than the values reported in the literature. Artificial neural network model has been developed for prediction of the surface roughness of the wire electrical discharge machined miniature gears. Very close agreement was found among the surface roughness values predicted by response surface methodology and artificial neural network with the corresponding experimental values.

Spark erosion machining of miniature gears: a critical review

“…The productivity of WSEM in the form of volumetric gear cutting rate was also analyzed and optimized. The research program was subdivided into four distinct stages, namely preliminary [32], pilot [6,10,33], main and confirmation experimentation stage [34][35][36].…”

“…This was followed by an optimization and confirmation stage consisting of nine experiments [2,35,36]. The conflicting objectives considered were minimization of geometric inaccuracy (profile error and pitch error) and surface roughness (average roughness and maximum roughness) and maximization of the WSEM process productivity (in terms of volumetric gear cutting rate).…”

“…A detailed discussion of the effects of WSEM process parameters (voltage, pulse-on time, pulse-off time and wire feed rate) on the microgeometry [36], surface roughness [35] and the process productivity [34] is presented. In essence, the ANOVA study found that all four WSEM process parameters significantly affect the outcome.…”

“…In essence, the ANOVA study found that all four WSEM process parameters significantly affect the outcome. Figures 11 and 12 depict the effects of the two important energy discharge parameters, namely, pulse-on time and voltage on the microgeometry and surface roughness of WSEMed miniature gears [35,36].…”

“…11), hydraulic forces (at high pulse-off times), short ( (a) Top view w (b) Isomet tric The formation of deep and irregular craters as a result of violent spark discharges at high-energy parameter settings (voltage and pulse-on time) (see Fig. 12), improper flushing of the molten material from the machining zone (at lower pulse-off time settings) and adherence of the wire on the gear flank surface (at lower wire feed rates) were the main reasons reported for deterioration in surface finish [35].…”