Laser welding in pulsed mode at 1064 nm is commonly used for small-scale welding applications. The welding process differs from CW mode in that every pulse has transients and hence a steady-state signal is not available for comparison. The difficulty in measuring transients also gives us an opportunity to use those transients to extract information about the weld. In this study we have employed two IR sensors and an acoustic sensor to determine the laser-material interaction during a pulsed welding application. Optical and electrical filtering techniques were employed to improve the signal-to-noise ratio to acceptable levels.
Bead-on-plate and lap welding experiments were conducted on 304 SS sheets. The monitor signals were successfully used to identify focus position. Use of weld monitor to set focus height removes the uncertainty associated with human interpretation. Lap welding experiments also show a strong correlation (R2 > 0.95) between both tensile strength and welded area at the lap interface and monitor signals. The strength of the weld is proportional to the welded area at the interface. Additional discussions include results from fillet and butt welding trials.