The effect of radial infeed on surface integrity in dry generating gear grinding for industrial production of automotive transmission gears

Reducing the environmental impact of machining processes is one of the greatest challenges facing mass production today. Nowadays, grinding represents the last step in the gear production chain and is the only process still requiring lubricant. In this respect, dry grinding for automotive gear production is a novel technique that has the potential to greatly improve the gear manufacturing process chain reducing environmental pollution due to the use of lubricants. In this study, a new machine developed for dry generating gear grinding is tested on three gears with different geometries, all of which are representative of high performance automotive transmissions. Thermal damage, or burn, is induced in gear grinding by an excessive thermal load applied to the workpiece surface during material removal. Therefore, starting from an optimized set up of grinding parameters suitable for industrial production, or rather, a configuration free from thermal damage, radial infeed is increased to achieve higher removal rates. The effects of stock removal on the surface integrity of the final produced part are then studied through microstructural analysis and micro-hardness measurements. It was observed that as radial infeed is increased, damage becomes progressively more evident in terms of microstructural degradation and changes in hardness. Differences in damage severity are observed between the three tested gears, with the gear module m found to be of greatest influence amongst geometric parameters.