Mechanical joining

Non-thermal joining of sheet material is used in almost all industries. Besides adhesive bonding, mechanical joining is getting more important, especially for joining of dissimilar materials. Modern high strength steels, whose mechanical properties are based on special heat treatments, can no longer be welded in the traditional way. New joining techniques must be used, which affect less the material properties. Mechanical joining techniques are ideal and offer numerous benefits that justify their use.


Clinching is a connection technology for sheet metals, which is a worthy alternative for resistance spot welding. In clinching, the sheets to be joined are locally strongly deformed, so that a mechanical connection is created. Additional elements are not used. In clinching, the connection is made by using simple tools: a punch, a die and possibly a blankholder. This technique has a number of advantages compared to spot welding, such as the low purchase and operating cost, little preparation work, safe and environmentally friendly, good mechanical properties, reproducibility ... The main uses of clinching can be found in the automotive industry, in air-conditioning and cooling systems, in household appliances (washing machines, refrigerators). The connection technology is primarily used for lightweight constructions in which combinations of materials such as aluminium-steel are used. The usability mainly depends on the formability of the materials. Suitable materials include aluminium, steels for cold work, soft and stainless steel, copper and bronze. Typically, material thicknesses up to 6 mm can be connected.


The parts to be connected don’t need to be pre-drilled, the rivet penetrates the parts. Accessibility of the joining zone from two sides is required. When using a hollow rivet, it is possible to cut through the upper plate, without pre-drilling (self-pierce riveting). For this technique, a matrice with a recess is used. The cylindrical shape of the matrice causes the rivet to expand, so that a mechanical connection is created. The rivet must possess special properties: a sufficiently high strength and hardness are required in order to be able to pierce the workpieces.

Advantages of mechanical joining

  • Fast, single operation joining process
  • Can be used on unweldable materials and dissimilar material combinations
  • Little or no damage to pre-coated materials
  • No fume or heat, low noise emission, low energy consumption

Feasibility study

BWI can assess the feasibility of these processes for your materials or applications. Through our partner network, we can also carry out joining  trials with subsequent full joint characterisation. For further questions, please contact Koen Faes.

  • dr. ir. Koen Faes

    Team Leader Research | Project Manager
    +32 (0)9 292 14 03