Machinability analysis of cemented carbide -A theoretical and experimental study

Abstract: Sandvik Coromant is the market leader of producing tools for advanced metal cutting. The tools are produced in cemented carbide, however Sandvik Coromant does not produce tools for machining cemented carbide. The aim of the thesis was to perform cutting tests in cemented carbide with diamond tools to investigate if the binder content affected the machinability of the process. The wear tests were performed in cemented carbide with two different binder contents H10F and H15F. H10F consist of 10% cobalt and 90% tungsten carbide while H15F consist of 15% cobalt, 84.3% tungsten carbide and 0.7% other. Two different types of tools were used in the experiment, a diamond coated cemented carbide ball nose mill and a nano-polycrystalline diamond ball nose mill. The wear tests were performed in a 5-axis mill from Mikron HSM200uLP and the tool wear was measured in an optical 3D microscope from Alicona. The surface of the workpiece was examined using a scanning electron microscope (SEM) and the surface roughness using a 3D optical microscope from Veeco in Västberga. The results show that the machinability is not affected by a change in binder content from 10 to 15% cobalt. Tool life and surface quality are more dependent on tool shape and tool material. The surface roughness obtained in the experiments range from 0.12 μm to 0.38 μm in Ra. Since the experiment did not focus on obtaining the optimal surface roughness it could be possible to select different cutting data in order to optimize the surface roughness. Future work could include testing of other tool materials such as nbcBN.