Improving wear resistance of sprocket parts using a fine-blanking process

Abstract

A sprocket is a toothed wheel, commonly used in drive systems, to which the strength and wear resistance of the teeth are important. Sprockets are conventionally fashioned by hobbing, followed by heat treatment. However, the fine-blanking process has recently seen increasing use by sprocket manufacturers. The process of fine-blanking has the possibility of reducing the number of process operations, thus reducing production time and cost, as well as improving part quality and process repeatability. Because of the severe plastic deformation in fine-blanking process, the strength, hardness and wear resistance of parts can be improved. In this work, the surface hardness and wear resistance of a fine-blanked sprocket are compared with those of a sprocket made using the hobbing process. The source of the wear resistance improvement was identified via examination of the microstructure. The microstructure of the fine-blanked sprocket revealed an increasingly compressed and elongated grain structure, in which grain flow and orientation resulted in pronounced hardening across the tooth width. The wear resistance of the fine-blanked sprocket, as measured by the distance between the teeth and the radius at the tooth bottom, was greater than that of the hobbed and heat-treated sprocket. Based on the results, the material cost of the sprocket could be reduced by using low carbon steel (SS400) instead of medium carbon steel (S50C), and further savings in production time would be realized by eliminating the need for subsequent heat treatment.