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Resistance and Mechanical Joining

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Resistance welding and mechanical fastening are two of the most widely used and well-established methods of joining.

TWI has a long and rich history of developments in these technologies, and we provide a range of services to members looking for guidance or resources relating to either discipline.

Resistance Welding

Resistance welding is defined as a process whereby force is applied to surfaces in contact and in which the heat for welding is produced by the passage of electric current through the electrical resistance at, and adjacent to, these surfaces.

TWI has longstanding, industry-based experience in resistance techniques, and has developed process and quality standards. We offer a comprehensive technical support service to assist with any resistance welding-related queries.

Resistance welding has an excellent track record for producing quality joints in sheet materials. In the European automotive industry alone, more than 150 million resistance spot welds are made each day.

Techniques covered by our expertise include:

  • Resistance spot welding
  • Resistance projection welding
  • Resistance seam welding
  • Flash and resistance butt welding
  • High frequency welding
  • Micro and miniature resistance welding 

Resistance welding support we provide to our members includes: troubleshooting, advice on best practice, development of new and novel techniques, fracture mechanics testing facilities, metallurgical support services, instrumentation and monitoring equipment and tailored training courses.

Mechanical Fastening

Mechanical fastening is a widely used, cost-effective means of joining, which is particularly suitable for thin sheet sections. Fastening encompasses a range of processes that utilise a variety of fasteners including nuts and bolts, screws and rivets, or mechanical interlocks to assemble materials without heating.

Our expertise in mechanical fastening spans sheet joining, plastics and composites and structural engineering. Our members benefit from a range of specialised support services, consultancy and project work.

We offer:

  • commercial clinching and riveting equipment
  • static, fatigue and impact testing equipment
  • advice on process selection and best practice
  • engineering design advice on machine-threaded fasteners
  • materials science support
  • expertise on hybrid joints: fasteners plus adhesives
  • information on the mechanical properties of fastened joints

The high production rate techniques that have been studied at TWI include clinching, which uses a special punch and die to form a mechanical interlock between the sheet metals being joined, and self-piercing riveting, in which a semi-tubular rivet is set using a punch and die to flare the rivet within the lower sheet so that no pre-existing hole is required.

All TWI's confidential consultancy and project work is conducted to ISO 9001 quality standard.

For more information, please email


For more information please email: