PSM Expansion nuts are specialized fasteners designed to provide a secure thread in panels or sheets where only one side is accessible. They are ideal when you need to fasten into plastic, sheet metal, or composite panels but can’t access the backside to install a nut or similar hardware. By expanding radially when the screw is tightened, expansion nuts lock themselves in place and resist loosening under vibration.
Advantages
- Vibration proof
- One side panel access
- High pull out retention
- Non-paint clogging
- Reusable
- Can be used in square or rectangular holes
MATERIAL
CS60, CS70 carbon steel, austempered
WHEN SPECIFYING, PLEASE STATE:
- Quantity
- Prefix (CBEN)
- Part No.
- Finish code (e.g. 5000 CBEN-0264-13)
How Expansion Nuts Work
An expansion nut is inserted into a square or rectangular hole (or slot) in the panel. As the screw is tightened, the nut’s walls expand outward, pressing against the hole sides to grip the panel securely. This expansion action generates friction and mechanical locking, preventing the screw from backing out. Because they expand after insertion, these nuts allow one-sided access installation. You don’t need to reach the reverse side of the panel to secure the fastener. Many designs are also re-usable, offering removal and reinstallation capability.
Advantages & Use Cases
Key Benefits
One-side installation capability
Vibration-resistant locking thanks to expansion grip
Simplified assembly: no necessity for backing hardware
Clean aesthetic: no exposed fastener from reverse side
Reusability in many designs
Typical Applications
Plastic housings and enclosures where access is limited
Automotive panels or interior trim parts
Instrument panels and electronic chassis
Thin sheet metal or composite panels where drilling through is possible but backside access is not
Method of Assembly
Push the expansion nut through either a square or rectangular hole in panel and simply tighten the screw down through the fastener.
Dimensional Data & Sizes
Push the expansion nut through either a square or rectangular hole in panel and simply tighten the screw down through the fastener.
Expansion Nuts Dimensions
* Denotes with earthing barbs
Dimensions in millimetres