What is Clinch Joining?

clinch joining sheet metal

Clinch joining is a fastening process used to join sheet metal parts without the need for welding, screws, rivets, or adhesives.

It is also known by the following brand names; Tog-L-Loc®, Rivclinch®, Tox®, and Pressotechnik. The process uses a small press and special tooling to locally and plastically form an interlock between two (or more) sheets.

clinch joining image

How clinch joining works?

In the case of a split female die, as the male or upper punch reaches a predetermined penetration, the female die quadrants expand, permitting the two pieces of sheet metal to bulge outward, creating something akin to a dovetail joint, except in this case circular. Upon punch retraction, the split female die quadrants also retract inward as the new interlocked joint assembly is removed.

Typical sizes for 16 GA sheet or under, are 3/16” – 3/8” diameter x 1/16” – 1/8” depression/projection.

clinch joining sheet metal enclosures

Pros of using clinch joining

  • No heat required: Safe for heat-sensitive or coated materials.
  • No consumables: No need for screws, rivets, or adhesives.
  • Cost-effective: Reduces material, tooling, and labor costs.
  • Fast process: Well-suited for high-speed automated production.
  • Eco friendly: Does not require pretreatments with solvents, acids, and other harmful liquids
  • Low cycle time < 1 second per joint
  • No pre-drilled or punch holes required (such as riveting)
  • Excellent for joining aluminum (which is difficult to spot weld)
  • Join different or mixed metals: e.g. steel to aluminum
  • Easily automated: it does not require skilled workers
  • Used on prepainted sheet metal (without damaging the paint unlike spot welding)
  • Reduced machine cost: typically, a small mechanical or hydraulic press is all that is required (See Fig. 1)
  • Cleanliness: The process does not produce flashes or fumes;
  • Flexibility: The same tools can be employed for a wide series of materials.
  • For larger assemblies that might be difficult to manipulate or orient to the press, hand held (pneumatic or hydraulic machines) can be used (See Fig. 2)
  • The mechanical strength of the metal material near the joint is generally increased due to both the mechanical lock and work-hardening.

When to use clinch joining

Clinch joining is an excellent choice when working with:

  • Thin sheet metals
  • Joining coated, galvanized, or painted metals.
  • Joining dissimilar metals where welding may be difficult.
  • Assembling components that do not require high structural strength at the joints.

Cons of clinch joining

  • Non structural, non load bearing fasting method
  • Visual: General not used when cosmetic appearance is required. The process leaves a small depression on one side and a projection on the other. 
  • Jigs may be required to hold workpieces in position before being joined because there are no pre-drilled or punched holes that help with locating or positioning.

Reviewing joining options with your metal fabricator early on in the design process offers to see if clinch joining can be used for your applications.

For more information please contact [email protected].