Welding of Plastics (XI)

Ultrasonic Welding of Plastics

Abstract

Ultrasonic welding is a process for joining plastics by the introduction of high-frequency vibration in the overlapping plastics to be joined.
No filler rods were used. The workpieces were clamped moderately under low static-force, and ultrasonic energy was transmitted to them for a brief interval.
The mechanism by which ultrasonic welds of plastics are produced has not been fully made clear but our resarches will bring it into light step by step.
Certain characteristics of ultrasonic welding of thermoplastics are apparent. For example, weld occurs when the tip oscillates in a parallel plane to the weld interface.
Static clamping force and oscillating force introduced dynamic stresses and plastic flow in the thermoplastics. A moderate temperature rise was noted in the weld zone.
It was known that the process of welding mainly depends on thermal deformation, material properties at room temperature and 1 st transition temperature.
The relations of these factors to microstructural bonding are complex. Spot-type ultrasonic welding machine was used at 2000 W inth a frequency of 22 kilocycles.