Wear behaviors of PCD and diamond-coated tools during low-frequency vibration-assisted drilling CFRP/Ti stacks

Abstract Carbon fiber reinforced polymer (CFRP) and titanium alloy stacks play a significant role in the aerospace field to improve the mechanical properties of assembly components. Low-frequency vibration-assisted drilling (LFVAD) can realize the periodic contact and separation characteristic between the tool and the workpiece, thus pose a high potential for manipulating the machinability of CFRP/Ti stacks. In the present study, two types of drilling tools (polycrystalline diamond (PCD) tool and diamond-coated tool) are adopted and tool wear behaviors are deeply evaluated during drilling CFRP/Ti stacks. Meanwhile, the specific influences of tool wear on the drilling performances are comprehensively analyzed under the LFVAD with minimum quantity lubrication (MQL). The results show that Ti-adhesion is observed for both drilling tools. Meanwhile, edge fracture is the key wear mode dominating for PCD tool and coating peeling is the main wear mode for diamond-coated tool, with less Ti-adhesion. In addition, with increasing number of drilled holes, the diamond-coated tool demonstrates better drilling performances with lower cutting force, better hole quality and more hole-making number. The findings of this paper can contribute to providing a guidance for tool optimal selection in low-frequency vibration-assisted drilling of CFRP/Ti stacks with MQL.