What are Threaded Inserts for Plastics?
Threaded inserts are metal components used to strengthen plastic parts in which screws are to be installed and removed more than once. Most inserts are made of brass, which provides long thread life as well as a solid, secure fastening base. However, they can also be manufactured from aluminum, stainless steel and free-machining steel.
Threaded inserts are commonly used to reinforce two types of plastic: thermoplastic or thermoset plastic. Thermoplastics are like wax. At usable temperatures they are solid, but at elevated temperatures they get soft and melt. In contrast, thermoset plastics have a molecularly cross-linked structure which is permanently “set” into shape during the manufacturing process.
Thermoplastic compounds are generally more resilient than thermosets and respond well to the ultrasonic or thermal installation of inserts. Thermoset compounds, however, are often brittle and less resilient than thermoplastics. They respond better to molding or post-molding cold insertion.
Tri-Star Industries’ threaded inserts for plastic come in a variety of styles and sizes to meet a variety of applications. They are manufactured to the following thread specifications: UNC-2B and UNF-2B for inch threads and ISO-6H for metric threads.