Chapter 11 - Ultrasonic welding of plastics and polymeric composites

Abstract

Ultrasonic welding is one of the most popular methods for joining plastics and it is becoming an important method for welding polymeric composites. This chapter begins with a description of the stages of a typical ultrasonic weld followed by the history of ultrasonic plastic welding. The chapter then continues with a description of the theory of ultrasonic welding including viscoelastic heating, wave propagation and attenuation, squeeze flow, and chain diffusion and entanglements. The next section is on design considerations for ultrasonic plastic welding including near-field vs far-field, general concerns, and joint design. It is followed with a description of a variety of ultrasonic processes including plunge and continuous welding, staking/swaging, spot welding, degating, and inserting. The chapter then discusses ultrasonic welding equipment including power supply and controller, stack, actuator and fixture, and a description of the different process control modes. Finally, the chapter discusses material weldability including compatibility and weld microstructure.