Wear Mechanism of pcd tools of different grain sizes manufactured by conventionally abrasive grinding and electrical discharge grinding

Abstract

With the development of the aviation industry, high-performance tools, which can overcome high temperature and severe abrasion, are in large demand in order to save manufacturing cost and increase machining efficiency in cutting hard-to-machine materials such as titanium alloys, composites and carbon fiber reinforced plastic. Poly crystalline diamond (PCD) tools have been widely applied in cutting difficult-to-machine materials in industry. However, the severe abrasion and high cutting temperature cause significant tool wear and reduce machining efficiency. In this paper, the processes of using ground PCD tools (the tools machined by conventional abrasive grinding) and eroded PCD tools (the tools electrical discharge grinding(EDG)) to cut tungsten carbide were investigated. By analyzing the morphology of worn surface and the change of cutting force, it was found that the wear and wear mechanism of PCD tools machined by EDG and abrasive grinding processes were different. In ground PCD tools, compressive residual stress within the PCD layer combined with external compressive stress exerted by work piece broke the diamond-diamond bonding, and led to the fracture of PCD structure around the tool tip. In contrast, the excessive heat in EDG process generated tensile residual stress within PCD structure and weakened the C-C bonding. The forming-removing cycle of build-up layer (BUL) and the breakage of C-C bonding during the cutting process caused a steady adhesive-abrasive wear process, which was the main wear mechanism of eroded PCD tools.