Capabilities evaluation of WSEM, milling and hobbing for meso-gear manufacturing

This paper describes manufacturing capabilities evaluation of wire spark erosion machining (WSEM), milling and hobbing to manufacture meso straight bevel gear (MSBG) and meso helical gear (MHG) made of SS 304 using microgeometry, macrogeometry, flank surface topology, surface finish, microstructure, microhardness, manufacturing time and cost, and gear material loss. Experiments were conducted using the parameters of WSEM, milling and hobbing processes optimized through trial experiments. This study reveals that WSEM manufactured MSBG and MHG possess better microgeometry (DIN 5-7), macrogeometry (29, 33, and 46 mu m deviation in span, tooth thickness and outside diameter for MHG), topology, higher microhardness, superior microstructure, lower manufacturing time (25 and 20 min, respectively) and cost ($ 4 for both), smaller loss of gear material but poor surface finish (1.07 and 6.60 mu m as average and maximum surface roughness for MHG and 1.04 and 6.16 mu m for MSBG) than milled MSBG and hobbed MHG. Microstructure study showed presence of burrs and marks of the cutting tool on the flanks of the best quality hobbed MHG and milled MSBG. It proves that WSEM is a superior, economical, material efficient, and environment friendly process to manufacture meso-sized cylindrical and conical gears of higher accuracy and better quality with excellent repeatability.