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
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.