 A fabrication technique involving the extremely rapid
impingement mixing of two chemically reactive liquid streams,
injected into a mold that results in the simultaneous
polymerization, cross-linking and formation of the part.
Typically, this low temperature process typically takes less
than a minute to complete, including time for mixing, curing,
and demolding.
This
technique is a form of liquid injection molding (LIM). When
short fibers (1.6 mm), carbon or mineral fillers are
incorporated into one of the liquids to increase modulus and
reduce coefficient of expansion the process is referred to as
reinforced reaction injection molding (RRIM). RIM resin systems
include epoxy which mold over continuous strand mat and preforms
as well as polyurethane/polyester hybrids, polyurea and
poly(DCPD).
Raw Materials
Liquid urethane in various combinations with liquid catalyst
Tooling
Machined steel or aluminum; cast aluminum.
Cost
Parts & tooling relatively high.
Advantages
Strong, flexible, lightweight parts which can easily be
painted.
Disadvantages
Slow cycles, expensive raw materials.
Applications
Automotive spoilers, interior trim panels for automobiles and
trucks. |
Molding
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