An investigation of laser spot weld variability in Kovar lap joints Available to Purchase

An experimental study of laser spotweld variability for 0.10 mm thick Kovar fillet lap joints has been completed. A fixture was fabricated to vary weld joint gap continuously between 0.0 and 0.25 mm. The maximum gap bridged was determined from many samples and used to evaluate the effect of changes in the independent process variables. An array of process parameters including pulse energy, duration, temporal shaping, beam diameter, and shielding gas were selected for the experiment. It was observed that changes in most process parameters did not improve gap bridging. Images of successful and unsuccessful fillet lap welds are presented. It is thought that due to surface tension effects, increasing or decreasing weld size did not provide additional molten metal to close the gap between the top and bottom plates. Some improvement in gap bridging was observed when the incident beam was angled to the weld joint at 30°, and when the beam was significantly offset towards the top plate side of the joint.