Fundamentals of three-dimensional Yb-fiber Nd:YAG laser machining of structural bone

Abstract

This work aims to understand the fundamental aspects of the laser-bone interaction in three-dimensional laser machining of the bone through an integrated experimental-computational approach. The study introduces 3-dimensional laser machining of bones through multilaser passes and attempts to establish the dimensional control over the laser-machined cavity through a finite element method based multiphysics computational model. A continuous wave Yb-fiber Nd:YAG laser (λ = 1064 nm) was employed with laser fluences ranging from 5.31 J / mm 2 to 25.46 J / mm 2 generated in combination of laser power (400 W-700 W) and machining speed (50 mm/s-250 mm/s). In multilaser pass machining, the optimum fill spacing of 0.2 mm was identified for higher machining rates with low deviation from linearity of machined edge (d = 9 μ m). This resulted in high machining rates ranging from 16.49 ± 0.2 mm 3 / s to 45.26 ± 0.66 mm 3 / s for a given range of laser fluence. The optimization for machining efficiency and physical attributes of the machined cavity were comprehended through thermodynamics and kinetics of the laser interaction with the bone based on the computational model for varying laser processing parameters.