Urethane Bushings
Urethane bushings are types of bearings used in automotive production as shock absorbers that maintain alignment and suspension components. They are ring-shaped products made of polyurethane, an elastomeric plastic resin containing organic elements and urethane. Bushings are designed to remove friction and ware or constrict and retain motion of mechanical parts, and those made from urethane are specialized for vehicle production because they last longer and control movement better than alternatives such as rubber, but aren't as harsh on car parts as metal. Urethane bushings are made of hard, rigid plastics and used in high impact areas.
The main drawback of using urethane bushings compared to rubber or metal is squeaking. This is easily combated by applying a lubricant, either regular grease or special urethane grease, which lasts longer. Urethane bushings are made from high performance polymers and often have friction-reducing additives. They are made through a process called reaction injection molding (RIM). During RIM, a polyisocyanate component and the polyurethane resin are injected into a mold, react and dry, creating bushings of different strengths, textures and colors. Each urethane bushing needs to be individually fitted during installation for optimal performance.