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Abstract This study compares gear surface characteristics generated by grinding, honing and superfinishing of case-hardened steel, including the evolution during efficiency testing with two different prior running-in loads (0.9 GPa and 1.7 GPa). The most influential factor was surface roughness. Micro-pitting was associated with surface asperities and hence only seen in ground and honed gears, while being absent for super-finished gears. The micro-pitting was enhanced by running-in load, but only for rough surfaces. Deformation-induced localized microstructure impact was associated with cracks. Residual stresses reached similar levels after efficiency testing. Phosphorous content in the gear surface was connected to surface roughness and running-in load. Highlights • The most influential surface characteristic was roughness. • Running-in load influenced the evolution of surface characteristics and micropitting, but only for rough surface. • Deformation induced localized bands confined to < 7µm were found to be in connection with the cracks. • The variation in residual stresses between as-manufactured conditions is associated with retained austenite content. • The phosphorous content in the gear surface was enhanced by the roughness and running-in load. [ABSTRACT FROM AUTHOR]

Micro geometry of a gear tooth influences the contact durability and wear performance. In this paper, different gear tooth flanks have been manufactured by different finishing processes, which were then characterized using multiscale surface analysis, based on wavelet transform. The friction noise was then measured before and after meshing in dry and lubricated conditions, to quantify the acoustic performance of the surfaces. To accomplish this objective, a new non-destructive sensory measurement technique was developed to characterize the friction noise generated by teeth flank surface. Results show the ability of the new method to discriminate functional behavior of different surfaces as well as give possible explanations as to the contribution of tooth flank asperities during the meshing on the gear in terms of gear noise performances. [ABSTRACT FROM AUTHOR]

The contribution of gear tooth flank surface micro-finish on gear noise has not yet been taken into consideration. This paper is devoted to study the simultaneous effect of tooth roughness and lubricant viscosity on automotive gear vibrations. The vibrations performances were evaluated on an instrumented test rig under both dry and wet conditions. A non-destructive replication technique coupled to 3D optical measures was used to acquire the flanks topographies, which were characterized using multiscale decomposition. A three-dimensional finite element simulation of a helical gear was performed to assess the micro-scales impact on gear noise. Numerical representative surfaces morphologies were introduced into the simulation and compared through the transmission error calculation. Results have shown gear noise dependence on tooth finishing processes. [ABSTRACT FROM AUTHOR]