Polymer Welding

TWI provides a number of services relating to the welding of polymers, including training, mechanical testing and non-destructive testing of the joints, troubleshooting and expert advice.

We have built up an extensive knowledge base covering all plastics welding processes, and all thermoplastic materials, including thermoplastic elastomers, and pioneered the development of innovative techniques that provide improved quality and greater productivity.

We can offer impartial advice on the most appropriate joining technique for any application or thermoplastic material. These welding techniques include ultrasonic welding, hot plate welding, hot gas welding, extrusion welding, high frequency welding, friction welding (including spin welding and vibration welding) and laser welding. The choice of which of these methods to use depends on factors such as part size and complexity, required cycle times and material.

Expertise and Equipment

TWI's technical excellence and equipment is made available to Members in the following ways:

Welding equipment and expertise for all processes, including process selection, joint design and development and validation of welding procedures
Non-destructive and destructive testing for plastics welds, including a specialised whole-pipe tensile rupture test rig
Process review and optimisation
Failure investigations
Personnel who combine many years' experience with cross-industry-sector knowledge and contacts
Plastic welder and weld inspection training and qualification via our industry training and certification programme
Advice on industry standards

Applications that involve welding plastics range from assembly for mass-produced domestic appliances to fabrication welding of pipelines and storage tanks, and from high-speed welding of films and fabrics to precision welding of medical devices.

Technology Challenges

Current technology challenges being focused on at TWI include:

Welding of dissimilar materials – dissimilar plastics and plastics to other material
Three-dimensional welds
Welding high-temperature polymers
Lifetime prediction of welds
Welding of technical textiles
Welding of wood
Digitalisation of plastics welding processes
Development of flaw acceptance criteria

Press Releases

Find out more about polymer welding at TWI:

Polymer Welding Experts Required for Standards Development

As an organisation, TWI has been instrumental in the development of British, European and international standards for plastic welding over the last 30 years.

Learn more

Real-Time Temperature Monitoring for Polymer Welding

TWI addressed the challenge of laser welding difficult-to-weld polymers through thermal management and control of interface temperatures.

Learn more

Core Research Programme (CRP) and Joint Industry Projects (JIP)

Joint Industry Projects

TWI also conducts Joint Industry Projects (JIPs) that bring together groups of Industrial Members to share the cost of research activities in areas of mutual industrial interest, gaining exclusive access to the outcomes. These projects cover a broad range of topics, including polymer welding.

Core Research

Each year the TWI Core Research Programme (CRP) addresses challenges on behalf of our Industrial Members as well as developing specific technologies and processes. Each of the projects under the CRP is focussed on engineering, materials or manufacturing technologies, including polymer welding.

Examples of Typical Projects

TWI has been carrying out internal research on plastics welding via its Core Research Programme for over 35 years. Please find below a list of Core Research Programme project titles:

- Member Report 1187: Diffusion bonding of polymer based micro- and nano-fluidic devices

- Member Report 1157: Effect of insufficient homogenisation of pigmented resin during the extrusion of polyethylene pipes on the mechanical performance of butt fusion joints

- Member Report 1154: Improvement of the reduced section tensile test specimen geometry for assessing the integrity of butt fusion welds in polyethylene pipes

- Member Report 1141: Effect of welding parameters on the integrity and structure of butt fusion welds in polyethylene pipes

- Member Report 1051: Effect of forced cooling on the integrity of polyethylene butt fusion welds

- Member Report 964: Literature review on forced cooling of butt fusion welds in polyethylene pipes

- Member Report 913: Correlating the long-term performance of electrofusion joints in polyethylene pipes with short-term tests

- Member Report 770: Qualifying long-term performance of butt fusion welds in PE pipes from short-term tests

- Member Report 730: The Clearweld™ process for laser welding of plastics and fabrics

- Member Report 708: A thermal model for transmission laser welding of thermoplastic polymers

- Member Report 647: Structural integrity of butt fusion welds in polyethylene pipes – comparison of short-term coupon tests

- Member Report 571: Ultrasonic and radiographic NDT of butt fusion welded polyethylene pipes

- Member Report 568: Structural integrity of butt fusion welded polyethylene pipes – a review

- Member Report 552: Thermal welding of polymers

- Member Report 533: A study of the applicability of the tensile weld test for thick walled polyethylene pipes

- Member Report 466: Structure evaluation of polyethylene and polypropylene hot plate welds

- Member Report 434: The butt fusion (hot plate) welding process for polyethylene pipe of 125 and 400mm diameter

- Member Report 419: The butt fusion (hot plate) welding process for polyethylene and polypropylene pipe – improvements to productivity

- Member Report 383: Assessment of mechanical property and fracture mechanics tests applicable to plain materials and welded joints in thermoplastics

- Member Report 382: A study of the butt fusion (hot plate) welding process for polyethylene pipe

- Member Report 370: The development of non-destructive test procedures for hot plate butt fusion welds in polyethylene

If your company is an Industrial Member of TWI, please contact library@twi.co.uk if you would like a copy of any of the above reports.

Altex (PDF)– Textile joining by laser welding, for waterproof garment and bed manufacture
Vascutek (PDF) – Replacement of blood vessels with textile vessels
PolyTank– Development of phased array ultrasonic non-destructive examination (NDE) for joints in polyethylene sheet
Powerweave– Development of textiles for electrical energy generation and storage – from making fibre forms of photovoltaic energy generation and energy storage through to the fabrication and evaluation of lengths of textile that can be used as a standalone power supply
PolyTest – Development of phased array ultrasonic NDE for joints in plastic pipes
Improving the quality and reliability of landfill storage by the training and certification of on-site welding personnel
A review of welding procedures and design guidelines for moulded plastic components to guard against failure in service, resulting in the development of a two-day training course and the establishment of a new specialist BSI committee
Core Research Programme projects
Friction stir welding of plastics
Pinweld - a novel process for joining plastics that uses a metal pin travelling with out-of-plane oscillating movement between two surfaces to be welded. Ideally suited to continuous welding applications

The diversity of these projects highlights the range of equipment and adaptability of the personnel within the Polymer Group.

Standards Activities

TWI is represented on the following committees:

BSI WEE/3 (Welding Thermoplastics)
BSI PRI/88 (Plastics Piping Systems)
CEN TC249/WG16 (Thermoplastics Welding)
ISO TC61/SC11/WG14 (Plastic Joining)
ISO TC138/SC5/WG17 (Alternative Test Methods for Plastic Pipes)

For more information please email:

contactus@twi.co.uk