High Efficiency Preparation of Microdrill Edge by Shear Thickening Polishing

The microdrill serves as precision cutting tool employed in the drilling of printed circuit boards (PCBs). The edge defects, such as grinding marks and burrs resulting from the grinding process, significantly impairs both the drilling quality and service life. Hence, it is imperative to meticulously prepare the cutting edge to ensure optimal cutting performance. In this paper, the cutting edge of cemented carbide microdrill was prepared by shear thickening polishing (STP) method. To achieve efficient cutting edge preparation of microdrill, STP experiment was carried out to evaluate the polishing force and determine the suitable processing parameters. Furthermore, the electrolysis combined shear thickening polishing (E-STP) method was employed in microdrill edge preparation, and the influence of different electrolytic voltage on the edge preparation effect was studied. The experimental results indicate that cutting edge preparation efficiency of microdrill in the STP process can be successfully increased by increasing the polishing speed, the main cutting edge radius increases from the initial 2.77 ± 0.4 μm to the highest 3.9 ± 0.3 μm after 2 min processing (polishing speed v = 85 rpm). The E-STP method is proven as an effective way in removing microdrill edge defects with a smaller polishing speed (v = 55 rpm). But, drilling experiments show that the wear resistance and drilling accuracy of the E-STP prepared microdrill (r average 3.6 μm) is significantly worse than that of the STP prepared microdrill (r average 3.5 μm) due to the Co loss. Overall, our research provides a new idea for realizing efficient cutting edge preparation of microdrill.