Thrust force, torque, and tool wear in drilling the bulk metallic glass

The thrust force, torque, and tool wear in drilling of Zr-based bulk metallic glass (BMG) material are investigated. Drilling the BMG at high speed generates the chip light emission, high tool temperature, and severe tool wear. At low spindle speed, the BMG work-material builds up at the major and margin cutting edges and may break the drill. A range of feasible spindle speed and feed rate for the efficient drilling of BMG without the detrimental chip light emission and cutting edge work-material build-up has been identified in this study. Under the same drilling condition, the WC-Co tool generally requires less thrust force and about the same torque than the high-speed steel tool. The progressive wear of the major and margin cutting edges for BMG drilling is examined. Severe drill wear is associated with the bright BMG chip light emission. Without chip light emission, the drill wear is visible but not severe. This study concluded that precision holes in BMG could be generated with proper selection of tooling and process parameters.