Inert gas cutting of titanium sheet with pulsed mode CO2 laser

The present work aimed at studying the dynamic behavior of melt ejection in laser cutting of I mm thick titanium sheet and to obtain dross-free cuts with minimum heat affected zone (HAZ). CO2, laser cutting of titanium sheet was carried out with continuous wave (CW) and pulsed mode laser operation with different shear gases namely argon, helium and nitrogen. Laser cutting with high frequency and low-duty cycle pulse mode operation produced dross-free cuts with no noticeable HAZ. Helium, because of its high heat convection and ability to generate high shear stress, produced laser-cuts with narrow HAZ and low dross, as compared to those produced with argon as the shear gas. Microscopic features of laser cut surfaces were analyzed and correlated with dynamic mechanism involved in laser cutting process. Process parameters for laser piercing, required for the initiation of fusion cut within the sheet, were also studied. Laser piercing requires either CW or high-duty cycle (> 80%) pulse mode operation. (c) 2005 Elsevier Ltd. All rights reserved.