Plastics extrusion is a high volume manufacturing process in which raw plastic

Plastic

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

 material is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weather stripping, fence, deck railing, window frames, adhesive tape

Adhesive tape

Adhesive tape is one of many varieties of backing materials coated with an adhesive. Several types of adhesives can be used.-Types:Pressure sensitive tape...

 and wire insulation.
In the extrusion of plastics, raw thermoplastic

Thermoplastic

Thermoplastic, also known as a thermosoftening plastic, is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently...

 material in the form of small beads (often called resin in the industry) is gravity fed from a top mounted hopper

Hopper

Hopper may refer to:-Mechanical parts:* A general term for a chute with additional width and depth for temporary storage* Hopper , a large container used for dust collection* Part of a combine harvester...

 into the barrel of the extruder.