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Glossary
Self-Clinching Nut
A self-clinching nut is a permanently installed fastener designed to anchor into sheet metal or thin materials by mechanically locking in place when pressed into a properly sized hole. It provides a strong, reusable internal thread in materials that are too thin or too soft to be tapped or threaded conventionally, such stainless steel, aluminum, or brass.
The self-clinching nut was originally developed by PennEngineering® (under the brand name PEM® nuts) and has become a standard solution for joining thin-gauge sheet metal in industries like electronics, automotive, aerospace, and enclosures.
The principle behind it is simple: when the nut is pressed into a punched or drilled hole using a press (not hammered), its knurled or serrated clinching ring displaces the surrounding material into an undercut groove on the nut’s shank. This creates a cold-flow interlock—the sheet metal plastically deforms around the nut, mechanically locking it in place. The head of the nut sits flush with or slightly above the surface, while the threads remain captive and can withstand repeated assembly and disassembly without stripping.
A key feature is that installation occurs without heat or adhesives, and once installed, the nut cannot rotate or fall out under normal torque or vibration. The surrounding sheet provides axial retention, while the displaced material around the undercut provides torque resistance.
There are several types of self-clinching nuts, each optimized for different materials and applications:
- Standard self-clinching nuts (type S) for steel or aluminum sheets.
- Stainless steel versions (type CLS) for corrosion-resistant applications.
- Floating self-clinching nuts, which allow minor misalignment between mating parts.
- Flush-head and mini versions, designed for low-profile assemblies or thin sheets.
Installation is quick and reliable—typically done with a hydraulic or mechanical press that applies steady pressure (not impact), embedding the nut cleanly and permanently. The resulting joint can achieve thread strengths comparable to a tapped hole in much thicker material.
