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The Injection
Molding Process in its simplest form is:
The process of taking plastic at room
temperature, heating it to a fluid state, forcing the
material into a cavity that is the
negative shape of the desired product, allowing the material to solidify, then remove the part from the mold.
A more technical description of the Injection Molding
Process is:
Placing material in the hopper of the Injection Molding press, Heating the
material in the barrel via band heaters and friction to a fluid state, forcing the material through the
Nozzle, entering the Sprue Bushing, then entering the Runner system (Cold
Sprue) and Gate,
the material then enters the Cavity which is a negative image of the desired
part, the material is held under pressure while it solidifies, then the part,
gate and Runner are Ejected from the mold.
Cold Sprue vs Hot Manifold /Runner
Cold Sprue molding means that the Sprue and Runner
material is solidified along with the part with each cycle of the press.
The scrap (sprue and runner material) are typically ground and either sold or
added to the virgin material in limited percentages.
Hot Manifold / Runner means that the material stays
is a molten state from the Injection Molding Machine until the gate. This
type of molding eliminates the sprue and runner scrap associated with cold sprue
molding.
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