Injection molding is the process of manufacturing plastic parts by forcing a polymer into a specifically shaped mold. A wide variety of products can be manufactured using injection molding. For example, the plastic-based bumpers on modern cars are often made through injection molding. Three primary types of polymers are used in injection molding.
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Thermosoftening Plastic
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Thermosoftening plastics, more commonly referred to simply as "thermoplastics," are polymers that soften and melt at high temperatures and harden again as their temperature falls. There is a wide variety of thermoplastics, including commonly used ones such as polyester. Thermoplastics are almost all 100 percent recyclable.
Thermosetting Plastic
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Thermosetting plastics usually begin in a liquid or soft-solid form and irreversibly harden when exposed to high temperatures. Thermosets tend to be inflexible and can be brittle. A commonly used thermoset is Bakelite, one of the earliest plastics developed. Today, it is often used in electrical insulation.
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Elastomers
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Elastomers are polymers that maintain their shape after being cured, usually with high heat, but also maintain a high degree of elasticity. Rubber is the most common example of an elastomer. Elastomers can reversibly extend, though the degree to which it can do so depends on the material's specific composition.
Read more: Types of Injection Plastic | eHow.com http://www.ehow.com/list_6192692_types-injection-plastic.html#ixzz1uOG57TZ0
