High precision turning of hardended steel - a challenge for a new generation of machine tools

An increasing number of high precision parts made of hardened steel are now required. By the continuous development in hard turning process technology the grinding of those parts can be replaced by turning. Machine tools have not yet been developed that meet these requirements. Because of their low stiffnesses and load capacities ultraprecision lathes can not be applied. Conventional turning machines are not accurate enough. New machine concepts combining high stiffness and high geometric accuracies are necessary. In order to demonstrate how the cutting process influences the machine tool behaviour, some basic research has been performed at the Fraunhofer- Institute. The report gives a survey of the state of the art in high precision hard turning. Aspects of process technology and problems that limit the achieveable accuracies are be described. They lead to a specification of parameters for a new machine tool concept.