Urethane Molding
Urethane molding, sometimes called polyurethane molding, is an elastic polymer that contains urethane carbamate links. Urethane is formed at a molten state and may be fabricated or molded into low-density flexible foam, low-density rigid foam, gel elastomer and hard, rigid plastics. Valued for its uses in rigid and flexible "memory" foams, urethane is also very useful in solid plastic form as well. Polyurethane molding combines many of the desirable qualities of plastic, rubber and metal with a longer life than other plastics, higher impact resistance than rubber, elastic memory, noise reduction, and heat and chemical resistance. Urethane moldings include a wide variety of pneumatic seals, press tool blocks, conveyor bushings, bumpers, bowling balls and parts for a broad spectrum of industries such as construction, automotive, food processing, engineering and athletic equipment. Urethane moldings offer high moldability, corrosion resistance a good strength-to-weight ratio and low processing costs.
The raw urethane molding materials are heated to molten form. During this stage, they react with one another to form a pre-polymer. When the urethane molding is ready to be processed, a curative is introduced to the pre-polymer in order to complete the polymeric transition. Accelerated by heat and pressure, the mixture is poured into a mold cavity and cured to form the final polymer. During open polyurethane molding, the pre-polymer and curative are heated and mixed together, poured into an open cavity and cured without the application of pressure. During closed polyurethane molding processes such as injection molding, the pre-polymer and curative are heated and mixed together, then injected into the closed cavity through small holes. Urethane possess several advantages over other elastomers and materials. It has higher resistance, greater load bearing ability, broader hardness range and better colorability than rubber. In comparison to metal, urethane offers better noise reduction, greater abrasion, corrosion and impact resistance and more flexibility. In certain applications, it has higher impact, more abrasion resistance, better elastic memory and noise reduction capabilities than other plastics.