Copper vapor laser micromachining of 304 stainless steel

A copper vapor laser (CVL) of 511/578 nm wavelength, 25 ns pulse width, and 10 kHz repetition rate combined With a computer controlled galvo head was used for laser micromachining of 304 stainless steel. The objective of this study was to develop the CVL micromachining process and its optimization. We observed a significant improvement in micromachining quality with a spatially filtered beam. Micromachining experiments were carried out on stainless steel strip samples of 75, 153, and 356 mum thickness. We studied the ablation rate using a singlepulse and monitored the heat affected zone (HAZ) as a function of the applied laser power density. The ablated volume and HAZ are directly proportional to the applied laser power density for low to medium laser powers (up to 2 X 10(13) W/m(2)). The ranges of HAZ diameter and ablated volume were 15.3-28.7 mum and 112.8-537.6 mum(3), respectively, for the applied power density in the range of 1.0-63.7 X 10(13) W/m(2). The roughness created by ablation process was studied at various pulse overlaps at laser power density of 87.8 X 10(13) W/m(2). Ablation depth and surface roughness were found to be inversely proportional to the center-to-center pulse overlap and directly proportional to the power density. (C) 2003 Laser Institute of America.