Clinching Machines Information
Clinching machines join metal workpieces by deforming two metal substrates, so that the underlying workpiece partially envelops the downward depression and lateral flow of the overload workpiece. This is accomplished by a clinching machine that consists of a punch and die. The die may be static or contain articulating blades to help form and release the clinch joint upon its completion. When the clinch is complete, the top workpiece will feature a small depression, while the bottom piece contains a similarly shaped extrusion.
Clingching requires no external hardware or consumables and produces no sparks or fumes. Substrates are not subjected to heat or a charge, meaning this process does not affect surface treatments or coatings. Clinches can be formed with minimal tolerances and are vibration resistant. Clinching is a highly repeatable, reliable, timely, and economical means of conjoining metal substrates.
Clinching is a fast, inexpensive, clean, environmentally friendly, and repeatable process. Typical clinching cycle times are under one second, and require no additional fastening components or chemicals.
Although the process may vary from one vendor or machine to another, the basic steps are the same:
- The two sheetmal pieces that are to be fastened are placed on the machine and clamped in place.
- A punch pushes or draws the metal into a die, deforming and locking the pieces together.
Clinching is an alternative to spot welding, adhesives, and rivets in many industries, such as automotive and appliances. The following table compares clinching to riveting and welding.
|Factor||Clinching||Self-piercing riveting||Spot welding|
|Base material suitability||Most materials with reasonable ductility; harder materials use semi-piercing tooling||Most materials with reasonable ductility||Most sheet steels; aluminium alloys more difficult|
|Metal coatings, e.g. zinc||Can be joined||Can be joined||More difficult for thick coatings and if passivated|
|Organic coatings/lubricants||Thick coatings can affect joint properties||Thick coatings can affect joint properties||Only thin, weldable coatings possible|
|Dissimilar metals||Possible||Possible||Metallurgical compatibility necessary;
aluminum to steel not possible
|Joint shear strength||Medium||High||High|
|Joint peel strength||Low||Medium||Medium|
|Cosmetic appearance||Hole one side, button on other||Flush one side, button normally on other||Slight indent both sides;
|Corrosion issues||Low susceptibility||Low susceptibility but special coatings required on steel rivets||Low susceptibility but some damage to protective coatings|
|Basic equipment cost||Low to medium||Medium to high||Medium to high|
|Cost per joint||Low||High||Medium|
|Workplace environment||Good||Good||Possible weld splash and fumes|
Table credit: TWI
In addition to riveting and welding, adhesives are an alternative to clinching. The advantages to clinching are that it does not require cleaning or preparing the surfaces, and the joining is instantaneous and permanent, where adhesives require time to cure and may degrade over time.
The following video illustrates the operation of a clinching machine:
Video credit: CPMFAB