SUSTAINABILITY OF GEAR MANUFACTURING WITH DRY GRINDING

High quality gears for automotive applications require a high level of geometrical accuracy and surface finish of the gear flank to improve the operational performance while reducing the noise during their lifecycle. Generally, the high-quality gears are produced using a final grinding process for surface finishing, this reduces the surface roughness and geometrical errors caused by the hobbing process and surface hardening techniques. Wet grinding is the most common method in conventional gear manufacturing for this final stage, however, it involves a massive amount of lubricant. Typically, oil or emulsion of oil and water are used as cooling fluids. As a result, every year tonnes of lubricant fluids are incinerated. This causes a significant environmental impact. Moreover, the use of lubricants possesses higher capital and operational costs and requires additional auxiliary equipment in the operation. Three grinding processes, which comprise the final finishing stage in gear production after the hobbing process were compared in this study. These processes include standard wet grinding, optimized wet grinding and dry grinding. In this study, five gears for each of the three process categories were tested under the same loading conditions and number of cycles i.e., 350 Nm and 1.5 million cycles respectively. The standard wet grinding was used as the reference process from Fiat Chrysler Automobiles (FCA) for this comparative study. After the torsional fatigue tests, the surface damages were measured and analysed on the gear flanks produced with each process category. Similarly, the damages for each gear's flank surface, which resemble a micro-pitting type of damage, were compared and the contribution of the final grinding process was identified to evaluate the vulnerability induced on the component by these finishing processes. Similarly, microstructural analysis and Vickers hardness results further added valuable conclusions for the three process categories. It was concluded that the dry grinding process possesses similar performance with respect to the reference grinding process ( FCA) and wet optimised process. Therefore, the feasibility of adopting the dry grinding process in the final stage of gear production is proposed considering the environmental impacts and additional cost of auxiliary equipment related to the use of lubricants. This research highlights the potential for innovative and eco-friendly practices within automotive industry, proposing a cleaner and more efficient gear production process.