The process of molding urethane involves mixing liquid, reactive, thermosetting chemicals (pre-polymers and curatives) in a fixed ratio. The resulting chemical action turns the mass into a solid form that can be cast into a variety of different shapes such as tubes, sheets, capping rings and bars. Urethane is also commonly known as thermoplastic polyurethane. The material is a thermoplastic elastomer (TPE) that combines the positive properties of rubber and plastic.
The time that is required to transform the liquid to the solid state is called the "gel time". Molding urethane into the required shape needs to be done in this gel time. Once the liquid is placed in the mold, it is allowed to set for an amount of time ranging from five minutes to eight hours. This is called the green time and the molded urethane is still very fragile at this point.
After the required green time is over, the mold is placed inside of an industrial oven and it is baked for several hours at a preset temperature. This process is called "post curing". Once the curing is done, the mold is subjected to aging and can later be cut or further processed.
Urethane is a very versatile material and it can be molded to produce many different products. They can be machined on conventional machine tools for the required shape and size.
- Urethane sheets: Are used for metal formings, cutting pads, gasket materials, hopper liners, wear pads, etc. They are available as molded sheets with fabric-backing or steel-backing. Sheets are available in thickness from 0.18 inches to 0.125 inches.
- Urethane bars and squares: They are available as bars varying in size from 3/8-inches wide and 24-inches long, to 6- inches wide and 48-inches long.
- Mining industry: Since urethane is wear resistant, it is used in the mining industry for a variety of equipment and applications like: liner-sheet crossover pads, classifier shoes, screening equipment, impact bars, etc.
- Corrugated paper applications: Used to prepare covers of anvils and blankets for the die cutting and rotary machines.
- Winter road surfacing: In winter, when the snowfall is heavy, urethane products are used to maintain the road. Products such as: spinner mounting hubs, track pads, track bands, grouser shoes, snow plough blades, paving equipment parts, spinners, etc. use molded urethane.