Inserts
generally serve an important functional purpose, but should be used sparingly
because of the costs involved. They may be used in plastic injected parts to
carry much higher mechanical stresses than plastic themselves, to transmit electric
current, to take wear and tear, to decorate the plastic injected parts, and to
aid in assembly work. Most of inserts may be made of copper, brass, aluminum
and its alloy, or steel, ceramics and including plastics.
The
great majority of inserts used in plastic injected parts are made by either
automatic screw machines or metal stamping machines. Fig 1 shows variety of
metal inserts used in molded plastic products, usually a medium or coarse
diamond knurl. (a) Projecting rivet. The end of the insert to be imbedded in
the plastic is rounded or chamfered. A chamfered or rounded end is desirable so
that the plastics will flow easily around the insert and manufactory easily.
The sharp corner on inserts which embedded may cause crack of plastic injected parts.
(b)Male
insert as bolts and female inserts as nuts should be provided with shoulders to
help prevent the plastic compound from flowing into the threads. Avoid using an
insert that has not been provided with a shoulder which the flash may flow on
the thread. A single sealing shoulder is better. A double sealing shoulder is
the best, but it is more expensive.
(c)Blind
female insert with internal threads. (d) Open ends female insert with internal
threads. (e)Blind hole female insert with internal threads and counter bore.
More information please click www.olimy.com
(a) (b)
(c) (d) (e)
Fig 1 Various designed
inserts
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