Theoretical modeling and experimental verification of laser drilling process of SS316

Abstract

Laser drilling is a critical manufacturing process widely employed in aerospace, biomedical, and precision engineering sectors, especially for materials like SS316 stainless steel due to its excellent mechanical and corrosion-resistant properties. This study focuses on the development of a theoretical model and its experimental verification for optimizing the laser drilling process using a Fiber-coupled pulsed Nd: YAG laser of wavelength 1064nm. The primary objectives are to achieve maximum circularity, minimum taper angle, and increased depth of cut rate in the drilled holes. A comprehensive theoretical model was formulated based on laser-material interaction principles, considering energy absorption, thermal conduction, phase transformation, and recoil pressure-driven material ejection. Key process parameters such as laser pulse energy, pulse duration, repetition rate, beam diameter, number of pulses, assist gas pressure and focal position were integrated into the model to simulate their effect on hole quality and material removal efficiency. To validate the theoretical predictions, a series of controlled laser drilling experiments were performed on 3mm thick SS316 samples using a pulsed Nd: YAG laser system of wavelength 1064nm. Experimental outputs were measured using high-resolution optical microscopy to evaluate circularity, taper angle, and drilling depth. A comparative analysis between theoretical and experimental results was carried out, revealing a high degree of agreement, particularly in predicting the hole geometry and drilling efficiency trends. The developed model proved to be a powerful predictive tool for process optimization, reducing the need for extensive trial-and-error experimentation. This work not only contributes to the understanding of pulsed laser drilling dynamics but also offers practical guidelines for precise micro-machining of stainless-steel components.