Scientific Implications in High Peak Power Nd:YAG Laser Material Removal of Al-30%SiC Composite

Abstract

This paper outlines the scientific implications of a high peak power, high beam quality Nd:YAG laser in manufacturing applications and discusses the significance of optimizing key laser process parameters in material removal characteristics of a Al-30% SiC composite. The potential applications of this emerging technology are primarily targeted towards advanced components fabrication in industries such as aeronautic, space, power generation, and automotive. Some of the unique advantages include better beam characteristics such as focusability, improved dimensional accuracy and tolerance, higher production rates, process maneuverability using suitable lens and fiber optic beam delivery systems, and elimination of mechanical tool wear in comparison to the traditional drilling techniques. Percussion drilling experiments were performed in two batches on 12.5 mm thick plates of Al-30% by volume of SiC composite material. The laser consists of a cw-pumped Nd:YAG oscillator followed by a cw face-pumped, total internal reflection Nd:YAG slab for the amplifier gain medium, a master-oscillator-power-amplifier (MOPA) configuration. Both the second harmonic wavelength (532 nm) and the fundamental wavelength (1064 nm) were used, with average powers ranging from 35 W to 90 W. Two pulse formats were employed: Q-switched or simultaneously modelocked and Q-switched. A concentric nozzle was used with O2 assist gas at 45 psig pressure at the regulator. The holes were produced both normal to and 45° angle to the surface. Based on the measured geometrical data, circularity and dross ratios have been proposed and correlated with the process variables. The absence of cracking was evident from the transverse cross-sections of the produced holes. Results of the microstructural aspects such as the morphology and concentration of alloying elements in the matrix and second phase constituents of the unaffected substrate and the nearby regions of the laser drilled holes provided encouraging evidence for the retention of similar morphology, minimal heat affected zone, and little or no recast layer, under select process conditions. The findings in this present study emphasize the uniqueness of this modern laser material removal technique as an advanced manufacturing tool with broader future potential.