Threaded Inserts and Compression Limiters for Plastics

Threaded Inserts provide durable, reusable threads to maintain bolted joint integrity throughout the intended lifespan of a plastic assembly. Because an Insert is generally twice the diameter of a screw, the shear surface is increased fourfold. This significantly increases the load carrying ability of the bolted plastic joint compared to one without a metal Threaded Insert. Threaded Inserts also allow the appropriate installation torque to be applied to a screw without stripping the threads, which is a common occurrence when screws are installed directly into plastic. Additionally, the metal threads of an Insert provide permanent creep resistance for the entire load path of the thread to maintain a durable threaded connection.

Plastics suitable for Threaded Inserts fall into two categories: thermosets and thermoplastics. Thermosets, such as Bakelite, epoxies, and polyester resins, undergo an irreversible chemical change when formed and require Molded-In, Press-In, or Self-Tapping Inserts as they cannot be heated and reformed. Thermoplastics, including ABS, Nylon 6-6, polypropylene, and polycarbonate, soften with heat and can accommodate Press-In, Self-Tapping, Heat/Ultrasonic, or Molded-In Inserts.

SPIROL’s Inserts are engineered for optimal rotational torque and tensile (pull-out) strength, with precision-designed knurls and threads to enhance performance. We offer a comprehensive range of Threaded Inserts tailored to your plastic type, installation method, and performance needs.

Compression Limiters protect plastic components from damage by absorbing compressive loads when a bolt is tightened ensuring joint integrity throughout the product's lifespan. SPIROL provides a robust selection of formed and machined Compression Limiters, including split seam, molded-in, oval, and solid wall configurations to accommodate a wide range of applications. Each type is engineered to support varying compressive loads, positional tolerances, and installation requirements. All formed Compression Limiters, except the Series CL220, feature zinc plating with a trivalent passivation coating and an organic sealant for corrosion resistance. This finish withstands 144 hours to white corrosion and 384 hours to red corrosion. Series CL220 Compression Limiters come standard with a zinc alloy thermal diffusion ArmorGalv® coating that provides at least 1,000 hours of corrosion resistance to red rust. Aluminum and brass machined Limiters have inherent corrosion resistant qualities, and do not require additional finishing.