Microgrinding hypereutectoid steels using laser-modified corundum abrasive materials

Abstract

Microgrinding of hypereutectoid steels is a process that is comparable to that of superfinishing using a fine grained honing tool. This process is especially suitable for finish machining components such as bearing races. This paper describes the morphological changes made to conventional grinding wheels when dressed with a highly focused laser beam. The microstructure is influenced by the cooling rate associated with laser processing conditions, and the resulting microstructure is significantly affected by the way grains are orientated in the resolidified layer of the grinding wheel. Cooling rates and orientated imaging confirm that a preferred orientation of grains along the (110) planes is the reason for the formation of cutting points on the newly formed grinding surface. The existence of competitive growth of grains also explains why certain area of the modified abrasive material removes material in an uneven manner. The experimental machining results also show that the abrasive material grinds away the workpiece material in addition to removing the newly created abrasive surface, which tends to suggest that continuous dressing of the abrasive material is normally required.