Analysis and multi-response optimization of gear quality and surface finish of meso-sized helical and bevel gears manufactured by WSEM process

This paper studies influence of and optimizes pulse-on time, pulse-off time, servo voltage, and feed rate of wire on microgeometry and surface finish of stainless steel meso-helical gears (MHG) and meso-bevel gears (MBG) manufactured by wire spark erosion machining (WSEM) process. Microgeometry of MHG was evaluated in terms of error in total profile and total cumulative pitch and that of MBG in terms of error in single pitch and total cumulative pitch. Average and maximum surface roughness values were used to evaluate their surface finish. Twenty-nine experiments with two replicates were conducted using Box-Behnken approach of response surface methodology thus manufacturing 58 meso-helical gears and 58 meso-bevel gears. It was observed that higher pulse-on time and servo voltage, and lower pulse-off time and feed rate of wire yield poor microgeometry and surface finish of MHG and MBG. Desirability function analysis based multi-response optimization was used to identify optimum WSEM parameters to manufacture the best quality of MHG and MBG. The optimized values of the responses were validated experimentally. It was found that WSEM can attain up to DIN 6 quality in microgeometry of MHG and MBG. SEM micrographs of the best quality MHG and MBG revealed accurate and uniform bore, tooth profile, flank surfaces free from burrs and sharp edges and without any undercut at root. Microstructural examination of these gears showed flank surfaces free from cracks, globules and pores. This study proves that WSEM is economical and technically superior process for near net-shape manufacturing of high quality MHG and MBG.