Tribological study of crankshaft bearing systems: Comparison of forged steel and cast iron counterparts under start–stop operation

Abstract The current work investigates the tribological functionality of crankshafts bearing systems focusing on the variation of shaft materials and their surface conditions. Tribological tests were carried out with a ring-on-disc test configuration representing the bearing-shaft contact under start–stop motion. Forged steel and cast iron shaft materials were sliding against an Al based bearing alloy. The surfaces in contact were analyzed by light and electron microscopy subsequently. The performance of forged steel depends on the overall roughness of the surface, whereas the tribological functionality of cast iron is mainly determined through its microstructure and the occurrence of metal flaps with burrs. The results prove the significance of proper surface finishing of forged steel and cast iron shaft materials in order to minimize wear in journal bearing systems. For both shaft materials good sliding performances with respect to optimized surface finishing can be noted.