How does extrusion molding work?


Quick Answer

In extrusion molding, small pellets are softened in a heated barrel and extruded through a plastic die mold. This creates a continuous strip of plastic that can be cut to size.

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Full Answer

Extrusion molding is one of the simplest molding techniques. It is popular for creating pipes, I-beams, optic fiber cables and even foods like candy canes and gum. A variety of materials from plastic to hard candy syrups can be molded with this process. A hopper at the top of the machine is filled with small pellets. When the machine is turned on, the pellets drop into a heated barrel.

The pellets are warmed in the heated barrel until softened or even liquefied. This makes it possible to extrude the material through the die and force it into the desired shape.

A screw-type extruder forces the material through the die, which features a negative cross-section of the final shape of the molded material. This molded piece is continuous as it leaves the die. The material may cool slowly on its own or be cooled more quickly with fans as it leaves the die. The molded product is usually cut to size while still somewhat soft.

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