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Plastic injection molding

Plastic injection molding is the primary process for manufacturing plastic parts used in consumer goods such as computer keyboards, monitors, bottle caps, cups and solid plastic articles. Plastic is known to be a very versatile and economical material that is used in many applications. Injection molding involves taking plastic in the form of pellets or granules and heating this material until a melt is obtained. Then the melt is forced into a split-die chamber/mold where it is allowed to "cool" into the desired shape. The mold is then opened and the part is ejected, at which time the cycle is repeated.

Contributors in Plastic injection molding

Plastic injection molding

Uniform cooling time

Manufacturing; Plastic injection molding

Cooling time the same throughout the part to avoid warping.

Cycle

Manufacturing; Plastic injection molding

Complete, repeating sequence of operations for injection moulding a part.

Unidirectional flow pattern

Manufacturing; Plastic injection molding

Plastic flowing in one direction with a straight flow front throughout filling.

Hesitation effect

Manufacturing; Plastic injection molding

Occurs in parts of varied thicknesses. The flow moves preferentially into a thicker area causing an adjacent thin area to freeze off while the thicker area fills. Gates should be positioned as far as ...

Constant pressure gradient

Manufacturing; Plastic injection molding

Pressure drop per unit length. The constant pressure gradient principle says that the most efficient filling pattern is when the pressure gradient is constant along the flow path.

Differential cooling

Manufacturing; Plastic injection molding

Occurs when one area of the part cools at a different rate or when the mould surfaces are at different temperatures. Warping can result from differential cooling.

Slide

Manufacturing; Plastic injection molding

Projection in the mould used to form the geometry of the part, which is not in the direction of the closing of the mould and must be withdrawn before the part can be ejected.

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