Breviary Technical Ceramics




Carbide tools have traditionally been used for turning, cutting and drilling. These conventional cutting materials, based on metals, can only withstand a limited thermal stress, and do abrade. They are therefore, typically, supplied with cooling lubricant.

Ceramic-based materials retain their strength at significantly higher operating temperatures. These new materials therefore permit higher machining speeds with higher process reliability and with the omission of cooling lubricants. This is not just helpful from the production point of view, but is environmentally friendly due to the question of disposal.

A range of such cutting materials is now available on the market based on aluminium oxide, silicon nitride and mixed ceramics, supplemented by polycrystalline, cubic boron nitride (PCBN). These are also outstandingly suitable for cutting hard materials with high values of Vickers hardness. In addition to simple hard turning, the use of hard turning before grinding is increasingly found in practice. Mixed ceramics and PCBN cutting materials are suitable for precision hard turning of workpieces with hardnesses of up to 64 HRC. Production times and production costs are significantly reduced through the high-speed machining of cast-iron materials and in hard cutting.

Silicon nitride ceramics have won a significant market share in high-speed turning, drilling and cutting of cast-iron in the manufacture of large series for the automobile industry and its suppliers. Mixed ceramics including polycrystalline cubic boron nitride are also being used more and more to replace grinding with turning.

Cutting ceramics must have significantly greater hardness than the material to be cut. This high hardness does, however, finally have an effect on the toughness of the cutting materials. Literature therefore often contains advice to the effect that cutting ceramics cannot be used for intermittent cutting. It must, however, be pointed out that it is perfectly possible to use PCBN materials to machine with intermittent cutting.


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