Tribological behavior of Al–6.5%, –12%, –18.5% Si alloys during machining using CVD diamond and DLC coated tools

Abstract

Abstract Tribological behavior of cast Al–Si alloys was studied by considering samples from hypo-eutectic (Al–6.5% Si), eutectic (Al–12% Si) and hyper-eutectic (Al–18.5% Si) compositions that were subjected to dry drilling experiments. Tool materials tested consisted of hydrogenated diamond-like carbon (H-DLC), CVD diamond coated and uncoated WC–Co drills. Tool failure mechanisms were identified and correlated with the drilling torques. The drilling torque vs. number of holes curves typically exhibited three stages, each identified with a characteristic slope (m). A failure criterion was established, such that when m ≥ 1.0 × 10− 2 N m the onset of tool failure in dry drilling of Al–Si alloys could be predicted. For hypo-eutectic and eutectic Al–Si alloys drilled using uncoated WC–Co the failure criterion was satisfied rapidly (