Compression limiters have only a couple features in common. Though they fall within the camp of inserts, they are unthreaded bushings that can be as simple as a short metal barrel. Sometimes it can have a flanged head, a knurled outer diameter, an undercut, or some combination of any of these features. The name describes the purpose of these parts; compression limiters keep plastic from becoming overloaded when a joint is too tight, which can cause the plastic to degrade. The metal compression limiter both provides a positive stop to indicate when the joint is “fully” fastened, and sustains any additional load caused by over tightening.


These parts can adopt any of the installation methods associated with threaded inserts but can also forego any of the features for a simple, pressure-fit, hollow cylinder. This is possible because without threads, the compression limiter isn’t concerned with torque-out or pull-out, and only counteracts the stress induced in the plastic. However, one of the more permanent installation methods may be useful for applications in which the compression limiter serves as an electrical contact point, or if more precise positioning is desired. In short, the name is a sort of catch-all to describe a wide variety of custom solutions to application-specific joint loading problems.

Compression limiters come in many varieties and all serve the purpose of protecting plastic panels from excessive stress and damage


Compression limiters are used anywhere from battery trays and intake covers in the automotive industry to computer housings and phone cases to protect the plastic components from being crushed in the event of a drop or mild crash. When a joint is overloaded, the load is sustained by the metal compression limiter rather than crushing the weak plastic surrounding it. Compression limiters can often be paired with threaded inserts when a strong joint is needed between two plastic parts.

Relevant products from PEM:

While compression limiters are highly customizable to the application and aren't available as standard parts, visit the SI® Catalog to learn more about what solutions PEM has to offer.

Flange Head compression limiter with helical knurl

Flange-Head Compression Limiter with Helical Knurl

Symmetrical compression limiter with straight knurl

Symmetrical Compression Limiter with Straight Knurl

Fully diamond-knurled compression limiter

Full Diamond Knurl Compression Limiter

Non-knurled, symmetrical compression limiter

Non-Knurled, Symmetrical Compression Limiter

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