AbstractThe past 15 years have seen major advances in the development of ceramic tool materials to give high cutting speeds and long tool lifetimes. These developments require rigid machine tools and high-power motors, and a change in the way the tool tips are used. The main areas of application of these new tool materials are in the aerospace industries and, to a somewhat lesser extent, in cast iron production. There is an ever increasing number of grades (and tradenames) available, and in this paper the background and development of the materials are described. Briefly, the materials may be classified as alumina or silicon nitride based; these base compositions, with alloying additions, form two main families of materials. The manufacturing routes are discussed as these influence both the grain size and the porosity of the finished material, and both these properties affect the behaviour of the materials in use. Finally, the wear of these tools is examined in the light of present understanding of the microstructures.MST/713