Fasteners and Sealing
Ultrasonic welding and laser welding offer new opportunities for joining plastics. Product manufacturers are under pressure to reduce the cost of assembling plastic components but without compromising quality. For those wishing to avoid adhesives, there are some new opportunities worth investigating in the fi elds of ultrasonic welding and laser welding, as Jon Severn reports.
Les techniques de soudage par ultrasons et par laser ouvrent de nouvelles possibilités pour assembler des composants en plastique. Les fabricants cherchent à réduire les coûts sans sacrifi er la qualité des produits en plastique assemblés. Pour ceux qui souhaitent éviter les adhésifs, de nouvelles possibilités apparaissent grâce aux techniques de soudage par ultrasons ou par laser, explique Jon Severn.
Ultraschall- und
Laserschweißverfahren bieten neue Möglichkeiten zum Verbinden von Kunststoffteilen.
Produkthersteller sehen sich unter Druck, die Kosten für die Montage von Kunststoffkomponenten zu senken, ohne dabei die Qualität zu kompromittieren. Für Hersteller, die Klebemittel vermeiden möchten, gibt es jetzt einige neue Möglichkeiten in den Bereichen Ultraschall- und Laserschweißverfahren, deren Untersuchung sich lohnt. Jon Severn berichtet.
Ultrasonic and laser welding offer opportunity for joining plastics
P
lastic components are found in most mass-produced goods today, but the choice of fastening method will depend on the component’s function, the application and whether the
component needs to be removed for maintenance or recycling at the end of the product’s life. However, a major concern for designers is how the assembly can be manufactured most economically. For those products where a permanent joint
is required, and where adhesives are unsuitable, designers are generally left to choose between several different types of welding. For the purposes of this present article, we will consider some of the latest developments in ultrasonic welding and laser welding, though it is appreciated that other processes - such as non-contact hot plate welding and infra red lamp welding - may be more appropriate for some applications. Ultrasonic welding has become very popular for a wide range of applications, from medical devices to automotive components, consumer products and toys.
The process is clean, fast, results in little or
no fl ash, and can be readily automated for high- volume production. A typical ultrasonic welding system will consist
of a nest in which the part is supported, a power supply, converter (or transducer - which converts the electrical energy into ultrasonic vibrations), booster (an amplitude modifying device) and a horn (or sonotrode - the tool that contacts the workpiece).
In addition, there will be a means of applying a clamping force to the joint and, of course, a controller.
Hermetically sealed joints
As well as being suitable for welding two components of the same material, with hermetically sealed joints if required, the ultrasonic process can be used for spot welding or to form heads on stakes so that components of different materials can be locked in place mechanically. Similarly, ultrasonic technology can be used on metal components such as threaded inserts to create strong, relatively low-stress joints in thermoplastic components. There have always been limitations to what can
Fig. 1. Telsonic Soniqtwist ultrasonic welding systems have a converter that is mounted tangentially to the booster, so the sonotrode exerts torsional vibrations on the workpiece.
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