The Study of High Speed Micro-Drilling Performance and Machining Quality of Coated Micro-Drills with Zr-C:H Coatings
The Zr-C:H coatings with various C2H2 flow rate were deposited on micro-drills (a diameter of 0.2 mm) used a closed field unbalanced magnetron sputtering system. The ultrahigh speed (drilling speed of 160000 rpm) through-hole drilling printed circuit board tests used to evaluate the drilling performance of the coated micro-drills. The rejection criteria of service lives of the coated micro-drills were evaluated using two different criteria: (1) a nail head ratio greater than 1.5; (2) a drilled hole surface roughness greater than 25.4 μm. Adopting a service life criterion of a nail head ratio of 1.5, the Zr-C:H-5 coating possesses the optimal high-speed machining performance, which yields a micro-drill lifetime of above 6000 drilled holes. It represents a three-fold improvement on that of an uncoated micro-drill and it also improves machining quality.
Liangchi Zhang, Chunliang Zhang, Jeng-Haur Horng and Zichen Chen
W. H. Kao et al., "The Study of High Speed Micro-Drilling Performance and Machining Quality of Coated Micro-Drills with Zr-C:H Coatings", Advanced Materials Research, Vols. 591-593, pp. 342-346, 2012