Experimental Study of Micro-hole Pecking Drilling in High Volume Fraction SiCp/Al7075 Composites with Variable Step Size

The objective of this paper is to enhance the quality and processing efficiency of 0.5 mm micro-hole in high volume fraction (55%) SiCp/Al7075 composites used for electronic packaging. Initially, an analysis is conducted on the trajectory of the variable step pecking drilling. Subsequently, a formula is proposed for calculating the machining contact ratio. Furthermore, a two-phase simulation model of SiCp/Al composite with 55% SiC content is created. The optimal process parameters for micro-hole variable step pecking drilling are determined by analyzing the branch test. The simulation results demonstrate that the proposed model exhibits superior predictive capabilities for the cutting force as well as the dimensions of the entrance and exit edge defects. According to the experimental results, variable step size pecking drilling not only achieves a cutting efficiency of 97.9% while reducing the number of drilling steps by 59% when compared to constant step size pecking drilling, but it also improves the quality of micro-holes as measured by cutting force, hole diameter, and defects in the entrance and exit edges.