Influence of the Tool Geometry on the Machining of Cobalt Chromium Femoral Heads

In the industrial processing of cobalt-chromium (CoCr) cast alloys, tungsten carbide and CBN cutting materials are mainly used. Ceramic cutting materials have a high hardness and only suffer a decrease in hardness of 50 % at 1200 °C compared to room temperature. This effect occurs with carbide at 800 °C. In addition, the pressure resistance is temperature dependent and decreases with increasing temperature. At room temperature, the compressive strength of alumina ceramic (Al2O3) is about 3000 N/mm2 and at 1500 °C only 100 N/mm2. The edge preparation has also an important influence on the chip formation, the chip transport, the tool wear, the surface integrity of the material and on the roughness of the workpiece surface. To investigate a new process, the influences of different cutting edge preparations and different cutting materials have been tested.