HIGH-SPEED MILLING OF ADVANCED MATERIALS

The productivity of machining operations can be increased and the qual ity of products can be improved by using higher cutting speeds than ap plied conventionally. However, High-Speed Milling (HSM) is much more t han just the high revolution speed of the spindle of the machine tool. In this paper utilization of HSM in the manufacturing of the products made of different advanced materials is described. Results are based on the collaborative investigation performed by VTT and HUT in close c ooperation with Finnish industry. Utilizing HSM in manufacturing of el ectrodes for electric discharge machining (EDM) does not permit the sp ecial properties of graphite as a workpiece material to be ignored. Ho wever, high chip removal volumes with economical tool life for relativ ely small end mills can be achieved when milling electrodes involving precise details. Polymer-matrix composites such as carbon and glass fi bre, which are usually considered difficult or even impossible to mach ine, have been high-speed milled by using advanced carbide and diamond tools. Tests for materials used typically in model and prototyping ma nufacturing have been performed in order to determine the minimum reli ably achievable thickness/height-ratio for thin ribs. The most interes ting application field of HSM is the finishing operations of tool stee ls. Products made of hardened tool steel and comprising three-dimensio nal surfaces have successfully been milled with special cubic boron ni tride (CBN) end mills without any significant tool wear.