Wheel wear behavior and its influence on grinding performance in electrical discharge diamond grinding of reaction-bonded silicon carbide

Diamond wheel wear is the greatest challenge for the high-efficiency grinding of SiC mirrors due to the need for the frequent dressing of the wheel. To realize the dressing of the diamond wheel in the process, the electrical discharge diamond grinding (EDDG) that combines conventional grinding (CG) and electrical discharge machining (EDM) was used to machine the mirror material of reaction-bonded silicon carbide (RB-SiC) considering its conductivity. However, the diamond wheel will experience quite different wear behaviors from those in the CG process due to the additional electrical discharge action in the EDDG process. As a result, different grinding performances will also be obtained. In this paper, the wheel wear behavior and its influence on grinding performance were investigated by a comparing test with the CG process in continuous EDDG of RB-SiC. The wear behavior and mechanism of the diamond wheel were investigated by a combination of morphology detection and spectra analysis. To explore the influence of wheel wear on grinding performance, the material removal rate (MRR), grinding ratio (GR), grinding force, and surface roughness were discussed based on the wear regulation of the diamond wheel varied with processing time. The result revealed that the electrical erosion was mainly responsible for the different wear behaviors and mechanisms of the diamond wheel in the EDDG process. Due to the dressing effect and material removal caused by discharge sparks, higher MRR, lower GR, lower grinding force, and lower surface roughness were obtained in the EDDG process.