Investigation of Wheel Wear and Its Effect on Forces Encountered in Grinding of Silicon Nitride

Abstract

A necessary goal in the study of grinding advanced ceramic materials is to define grinding conditions that will machine ceramic components economically while maintaining dimensional accuracy and surface integrity of the resulting parts. In view of the high price of diamond wheels, which are the optimum choice for machining ceramics, it is important to investigate the process of diamond-wheel wear in grinding ceramic materials. Little information is currently available on the rates of diamond-wheel wear in grinding ceramic materials.<P>This thesis processes a new method of measuring wheel wear using a duplication pattern of the grinding wheel. Plunge-grinding experiments on sintered silicon nitride (SSN) and sintered reaction-bonded silicon nitride (SRBSN) were conducted using a horizontal-spindle surface grinder with diamond-grit, resin-bond peripheral wheels. To gain a better understanding of the wear process, grinding forces were measured using a computer-based data-acquisition system. Stylus profilometry served to measure the volumetric wheel wear and to measure the surface roughness of the ground silicon nitride for the purpose of characterizing the effect of wheel wear on the grinding performance. Major contributions of this thesis research include development of a method for measuring wear of diamond grinding wheels, and identification of the interrelation between the rate of wheel wear and the two machining parameters (namely, downfeed and wheel speed used in the investigation).