Dry Grinding: A More Sustainable Manufacturing Process for the Production of Automotive Gears

Abstract

Gears represent a fundamental component of automotive transmissions, the performance of which is directly influenced by flank surface integrity. With the exception of grinding, gear production does not require the use of lubricants. The elimination of oils in the final finishing phase represents an important opportunity to greatly improve process sustainability and reduce production costs. However, dry grinding presents several challenges, including dimensional tolerances and roughness requirements, microstructural defects due to excessive heat generation, and maintaining the overall surface integrity of flanks such that wear resistance is not compromised. The present work investigates the geometric accuracy, microstructure, and wear resistance of FIAT 500 4/6 speed gears manufactured by FCA/Stellantis, comparing conventional wet grinding with two alternative processes including superfinishing and dry grinding. The material and manufacturing processes employed prior to grinding were the same in all cases, with grinding then performed by the same manufacturer. The dimensional accuracy, roughness, microstructure, residual stress state, and wear resistance of gear flanks were then analyzed to compare the overall performance of each grinding process. The obtained results show that dry grinding can produce gears with acceptable geometric accuracy, no microstructure defects and greater wear resistance than gears finished with conventional wet grinding or superfinishing. As a result, the complete elimination of lubricant in gear production is possible, leading to a more sustainable process without compromising gear performance.