Laser joining of metals to plastics with ultrasonic vibration

Ultrasonic-aided laser joining process (UAL) for bonding metals to plastics has been further developed. With the application of an appropriate ultrasonic transducer tool, the quantity of laser-induced bubbles in the bonding zone can be significantly reduced. The removal mechanism of these bubbles from the molten plastic zone was analyzed based on pressure induction on the sample under ultrasonic vibration. Some experiments on joining titanium to polyethylene terephthalate have been conducted to ascertain the superiority of UAL over the conventional laser joining process. The joint strength, measured in terms of failure stress, was significantly increased when ultrasonic vibration was employed during laser joining. The joints formed without vibration always failed by separation along the metal-plastic interface, whereas, for the UAL joints, fracture occurred in the parent plastic material.