Optimization of Nd:YAG laser welding parameters for sealing small titanium tube ends

The purpose of the present study is to optimize Nd:YAG laser welding parameters to seal an iodine-125 radioisotope seed into a titanium capsule. If the end of a small titanium tube is irradiated to a Nd:YAG laser beam and melted down to the adequate length, it will be coalesced and sealed. The accurate control of the melted length of the tube end was the most important to obtain a sound sealed state. The effects of the laser welding parameters on the melted length were analyzed and optimized by the Taguchi and regression analysis method. The laser pulse width and focal position among the welding parameters had the greatest effects on the S/N ratio of the melted length. Optimal welding conditions were obtained at 0.86 ms of the pulse width and 3.18–3.35 mm of the focal position in the scope of the experiments. Confirmation experiments were conducted at the optimal welding conditions, and showed that both of the titanium tube ends were sealed soundly.