A Laser Joining System for Titanium and Polyethylene Terephthalate Plastic Controlled by Multiple Signal Sources

Laser direct joining of metal and plastic plays a significant role in manufacturing of multiple material structures. To improve the strength of the joint, a controllable laser joining system was developed for polyethylene terephthalate plastic and titanium based on the detected multiple signal sources. The main contribution of this paper lies in sensing 1) the intensity of thermal radiation to control process heat by adjusting the laser power; and 2) the reflection of the helium-neon laser to control the movement of the specimens. The response speeds of thermal radiation intensity when increasing or decreasing the laser powers were measured to guide the adjustment of laser power. The intensities of reflective light before and after the joining process were measured to guide the movement control. Then, the integrated control process was set up. Width, tensile shear strength, and fracture position of the joint produced by the controllable joining system were compared with those produced by the conventional constant power method, which validated the advantage of this newly developed system.