Effects of Metal Absorber Thermal Conductivity on Clear Plastic Laser Transmission Welding**Supported by the National Key R&D Program of China under Grant No 2016YFA0401100, the National Natural Science Foundation of China under Grant No 61575129, and the National High-Technology Research and Development Program of China under Grant No 2015AA021102.

Abstract

In our previous study, metals have been used as absorbers in the clear plastic laser transmission welding. The effects of metal thermal conductivity on the welding quality are investigated in the present work. Four metals with distinctly different thermal conductivities, i.e., titanium, nickel, molybdenum, and copper, are selected as light absorbers. The lap welding is conducted with an 808nm diode laser and simulation experiments are also conducted. Nickel electroplating test is carried out to minimize the side-effects from different light absorptivities of different metals. The results show that the welding with an absorber of higher thermal conductivity can accommodate higher laser input power before smoking, which produces a wider and stronger welding seam. The positive role of the higher thermal conductivity can be attributed to the fact that a desirable thermal field distribution for the molecular diffusion and entanglement is produced from the case with a high thermal conductivity.