《TGN-MS-04 Ultrasonics》.pdf

TGN-MS-04 ULTRASONIC WELDING OF PLASTICS USED Rev: 0 ABN 69 003 696 526 IN MEDICAL DEVICES Date: 21 April 2006 Pages: 6 1. PROCESS OVERVIEW Ultrasonic welding, for thermoplastic injection moulded components, is a process that uses mechanical vibrations above the audible range. The vibrations, produced by a welding sonotrode or horn, as it is generally known, are used to soften or melt the thermoplastic material at the joint line. The components to be joined are held together under pressure and subjected to vibrations, usually at a frequency of 20 or 40 kHz. The ability to weld a component successfully is governed by the design of the equipment, the mechanical properties of the material to be welded and the design of the components and joint. Ultrasonic welding times are short (typically less than one second), which makes the process ideal for mass production. The process is widely accepted in many applications ranging from automotive light clusters to consumer electronics products, such as mobile telephone casings. Figure 1: Ultrasonic Welding Machine (Reproduced by permission TWI Ltd) 2. ULTRASONIC WELDING EQUIPMENT Ultrasonic welding equipment consists of a machine press, generator, converter or transducer, booster, sonotrode or horn, and component support tooling. A schematic of an ultrasonic welding machine is shown in Figure2. Figure 2: Ultrasonic Welding Machine