THE APPLICATION OF POLYCRYSTALLINE DIAMOND (PCD) TOOL MATERIALS WHEN DRILLING AND REAMING ALUMINUM-BASED ALLOYS INCLUDING MMC

Following a review of metal matrix composite (MMC) materials and produ ction methods. the paper outlines the development and application of P CD cutting tools. Experimental data are presented for the drilling and single blade reaming of aluminium-silicon alloys containing 7% and 13 % silicon and aluminium 2618 MMC alloy reinforced with 15 vol% silicon carbide (SIC) particulate. Though initially aimed only at aerospace a nd defence products, MMCs have progressively moved into higher volume applications and are currently under evaluation for volume automotive components. Compared with standard hypoeutectic and hypereutectic cast aluminium-silicon alloys, tool wear when machining MMC is shown to be up to seven times more severe. Tools used for drilling include HSS-M2 , diamond plated HSS, WC, TiN coated WC and PCD. Other than when using PCD drills, tool life was extremely short due to the abrasive nature of the (SIC) reinforcement. Similarly, results from PCD reaming tests confirmed that diamond tooling provides the only realistic tooling opt ion.