Machining of an aluminum/SiC composite using diamond inserts

Experimental results in the machining of a SiC-reinforced aluminum metal–matrix composite (MMC) with diamond inserts are presented in this paper. MMCs are very difficult to machine and diamond tools are considered by far the best choice for the machining of these materials. Two types of commercially available diamond tools were examined: brazed polycrystalline diamond (PCD) tools; and chemical vapor deposition (CVD) diamond coated tools. The present results showed that the initial flank wear on both the PCD and the CVD diamond tools was generated by abrasion due to the very hard SiC particles present in the workpiece material. As machining progressed, thin films of the workpiece material were found to be adhering to the worn areas. Further tool wear in these areas is believed to be caused by a combination of the abrasive wear and the adhesive wear mechanisms. This explains the faster rate of flank wear on the CVD diamond insert than that on the PCD insert observed in the experiments.