Development and application of coated ceramic cutting tools

Abstract

Ceramics are characterized by their special wear and temperature resistance. Thus, they are especially suited for the cutting of high-temperature alloys and difficult-to-cut materials. Due to their low ductility, they show brittle-hard properties during the process, which lead to a sudden failure of the tool. But it is possible to create composite materials that counteract the brittle-hard behavior of the substrate material by PVD-coating. The objective of the investigations is to increase the process stability of coated ceramic indexable inserts made of aluminum oxide and silicon nitride through the optimisation of the mechanical pre-treatment of the substrate materials. To this end, the ceramic substrates are pre-treated by different abrasive machining processes. Comprehensive measurement evaluations show the influence of the machining process and strategy on the formation of surface and subsurface. The workpieces ground and lapped in different ways are subsequently coated by an especially developed PVD process. Measurements show the influence of the pre-treatment on the surface structure and on the mechanical properties of the composite material. The application of the developed and manufactured tools in cutting tests verifies the results of the measurements.