Linear vibration welding as a method for joining plastic pipes has been investigated at TWI. This process will reduce welding and cooling time and the overall costs of installing polyethylene (PE) pipes.
Results from tests show that linear vibration welding is potentially more cost effective than methods currently used in industry - hot plate welding and electrofusion welding. Cycle times are shorter (up to 1/50 of other methods)and energy consumption is less than with traditional techniques. This method has been in use as a plastics joining technique in the automotive and domestic appliance industries since the mid 1970s, but further development is needed to fully commercialise it for on-site and factory joining of plastics pipes.
Initial welding trials were carried out at TWI on two types of PE pipe -125mm SDR 11 PE80 and 180mm SDR 17.6 PE100. Results showed that welds can be produced with an overall weld/cool time of less than 30 seconds. When tensile tested, such welds failed in a ductile manner with welding factors greater than 0.9.
This initial work examined the linear vibration welding of PE pipes, but the technique is also suitable for joining any extruded or moulded component made from almost any thermoplastic material.