Fracture phenomena by machining of glass and rocks with diamond tools

Machining of glass and rocks (grinding, sawing, drilling) with diamond tools occurs generally by cutting of the materials with diamonds embedded in the tools. The grinding of glass has been simulated by cutting dry glass surfaces with a single diamond. Cutting speeds were varied up to 100 m/s. The complex microscopic fracture processes have been analysed with microscopic high speed photography during the cutting process and subsequent scanning electron photography fracture to plastic removal by chips. The obtained results will be compared with data from cutting- and identation-experiments on rocks reported in the literature. In spite of the very different material properties of glass and rock some similar features of fracture can be detected. Differences in the fracture processes for brittle and ductile behavior will be discussed. (IWM)