Clinching (metalworking)

Clinching is a mechanical fastening method to join sheet metal without additional components using special tools to plastically form a mechanical interlock between the sheet metals.

The tools consist typically of a punch and a die. There are two primary types of dies: solid "fixed cavity" dies, and dies with moving components. The punch forces the two layers of sheet metal into the die cavity forming a permanent connection. The pressure exerted by the punch forces the metal to flow laterally.

Clinching is used primarily in the automotive, appliance and electronic industries, where it replaces spot welding very often. Clinching is a cold forming process and does not require electricity or cooling of the electrodes commonly associated with spot welding. Also, clinching does not generate sparks and fumes. In addition, the strength of a clinched joint can be tested non-destructively using a simple measuring instrument to measure the remaining thickness at the bottom of the joint or the diameter of the produced button depending on the type of tools being used. Life expectancy for clinching tools is in the hundreds of thousands of cycles making it a very economical process.

An additional benefit of clinching is the capability to join prepainted sheet metal commonly used in the appliance industry without damaging the painted surface. Clinching has also become an important means of fastening aluminum panels, such as hoods and decklids, in the automotive industry, due to the difficulties involved with spot welding of aluminum.

This method of joining the sheets are used for the joining the GI sheets of ELECTRICAL BUS BARS for better finish