Manufacturing of Twist-Free Hardened Surfaces by Start-Stop Turning Method

Conventional turning results in surfaces with a twisted surface structure. However, for some applications of machine parts, twist-free surfaces are recommended. These surfaces can be obtained by grinding or turning with special one-purpose machine tools. Alternatively, a proprietary start-stop turning method can be used and applied on multi-purpose turning machine tools. In order to manufacture twist-free surfaces with start-stop turning, a conventional lathe is equipped with an additional short-stroke air bearing drive system. A series of experiments with specimens of hardened steel is performed and the effects of the process parameters \({n}_{v}\) (number of workpiece revolutions in the stop-phase) and \({v}_{Hub,v}\) (short-stroke velocity in the positive direction of the machine tool feed motion) on the surface properties are investigated. The results show that the surface structure and the so called transition area lengths can be influenced by the settings of process parameters \({n}_{v}\) and \({v}_{Hub,v}\). The findings can be used to predetermine surface structures for machine parts and applications such as surfaces with demanding requirements regarding tribology.