High power, short wave infra-red emitters from Heraeus Noblelight Ltd are being used in an adapted rig at TWI to demonstrate and prove the benefits of infra-red, non-contact welding of plastics over competitive techniques.
These emitters have been especially developed for applications in the plastics industry and can be supplied with different emission spectra to match the absorption properties of the material to be heated and in various shapes and sizes to meet specific heating applications and geometries.
The rig at TWI consists of two banks of six short wave 1.5kW emitters on either side of a moveable platten to give a total installed power of 18kW. The platten is advanced to the butt ends of the pipe without making contact. The power is switched on and the emitters illuminate the pipe ends for a predetermined heat time. The platten is then retracted, the power switched off and the softened pipe butt ends are brought together under pressure to effect the weld.
This technique offers a number of advantages over other processes such as hot plate, vibration and friction welding and plastics gluing. Being a non-contact method, there is no possibility of plastic adhesion to the heating surface necessitating tool cleaning. It is also capable of handling large surface area products as it is an easy step to add more emitters to a heating bank.
The infra-red welding rig at TWI is available for proving trials on a variety of plastics and product geometries. For more information, contact Ian Froment. E-mail: ian.froment@twi.co.uk .
