Laser micro drilling of 316L stainless steel orthopedic implant: A study

Abstract

It has recently been shown that there is a requirement of inclined micro hole with smooth side walls (without cracks and burr), high aspect ratio, low taper, reduced heat affected zone (HAZ) and thin recast layer on orthopedic implant. So with the aim of improving hole quality characteristics and functionality of implant a multi-objective optimization of laser micro drilling with argon as an assist gas is addressed in this study. A hybrid statistical approach based on grey relational analysis (GRA) and coefficient of variation (COV) is proposed to analyse the experimental data. The key process variables responsible for quality improvement are identified. Four statistical tests are performed to compare the hybrid and GRA approach. Further, it was found that the proposed hybrid is more superior to GRA in terms of computational time and ease of computation. It is also observed that focal point position and diode current have striking effect of hole quality. An important implication of this paper is that thin recast layer, small HAZ width and spatter area were observed, when argon was used as an assist gas.