Ultra-precision machining of hard and brittle materials with coarse-grained grinding wheels

Many attempts have been made to achieve optical surfaces on hard and brittle materials by means of ductile diamond grinding using fine-grained diamond wheels. However, the large wear rate of the fine-grained grinding wheel, which is caused by dressing and by the grinding process, limited the achievable form accuracy and the maximum material removal volume, especially in case of ductile grinding of large optical surfaces. For solving this problem, a novel-type diamond wheel must be applied which features much higher grinding ratios than that of fine-grained diamond wheels to guarantee the machined surface form accuracy in ultra-precision grinding of hard and brittle materials. In this chapter, the precision conditioning methods of coarse-grained diamond wheels for ultra-precision grinding will be presented first. Subsequently, the ultra-precision grinding of hard and brittle materials with coarse-grained grinding wheels will be investigated in order to reveal the performance of these novel diamond wheels. To conclude the chapter, micro-structured surface will be machined on the diamond grain surfaces of coarse-grained wheels for improving ground subsurface damage.