The purpose of this paper is to find economical machining speed during turning of grooves for piston rings with various feeds. In the first part of the paper, literature analysis concerning durability of cutting tools is presented. Next, the wear of cemented carbide cutting tools during turning of cast iron is researched. The research has been done for seven cutting tools. During conducted turning trials, angular speed has been altered from n=530rev/min to n=710rev/min and feeds from f=0.007mm/rev to f=0.105mm/rev. On the basis of Taylor’s equation, which relates cutting speed to tool life, the economical cutting speed is established with the application of two various methods.