Adiabatic Extrusion – A type of extrusion whose only source of heat is the conversion of the drive energy through the viscous resistance of the plastics mass in the extruder.

Back Pressure – The resistivity of molten plastic material to forward flow.

Barrel – The part of the extruder encasing the screw or plunger.

Barrel Liner – The sleeve forming the inner surface of the barrel.

Calendering – The process of pressing or smoothing material between rollers.

Cladding – Sometimes referred to as “sidings,” it is extruded PVC-U boards that are used as outdoor weather-resistant façade panels.

Compound – Any plastic material prepared for subsequent manufacturing processes, specifically extrusion, molding or calendering.

Compression Section – The transition section of a screw channel in which a reduction in the screw channel volume occurs.

Cooling Tank – A tank typically containing water through which extrusion is constantly passed for cooling.

Cure – The technique of cross-linking a plastics material.

Decompression Section – The section of a two-stage extruder in which an increase in screw channel volume occurs.

Die – The component on a plastics extruder affixed to the extruder head through which the melt is pushed to form the desired profile.

Die Plate – In moulds, the main support for the punch or mould cavity.

Dry Blend – A free flowing blend of compound or resin and other ingredients as prepared for an additional manufacturing operation specifically for extrusion or molding.

Extrudate – The product or result of an extrusion process. An extrudate is a product or material forced through a shaping orifice as a continuous body.

Extruder Size – The minimal inner diameter of the extruder barrel

Extrusion Coating – A coating technique in which molten plastic feeds directly from an extruder die into a nip-roll assembly combined with the substrate.

Haul-off – Also called a “caterpillar,” it is an apparatus used for the continual removal of extrudate from the die.

Heat Aging – The unique process of aging a thermoplastic or thermoset product and examining the percentage of retained physical and chemical properties after exposure to heat for a prolonged period of time.

Melt – Any extrusion material heated to a plastic condition.

Melt Strength – A term that refers to the strength of molten plastic.

Outer Die Ring – The element of tubing tie that shapes the outer surface of a tube.

Pellets – Resins or mixtures of resins with compounding additives in the shape of similar-sized tablets and granules that have been extruded or chopped into short segments to prepare them for molding operations.

Ram Extruder – A barrel with a temperature control, wherein a plunger pushes material in a melted state to the die.

Resin – Any of several physically similar polymerized synthetics or chemically altered natural resins, such as thermoplastic materials (polyvinyl, polystyrene, polyethylene) or thermosetting materials (polyesters, epoxies, silicones used with fillers, stabilizers, pigments).

Screw – A helically grooved rotating element inside the barrel of a screw extruder. The main purpose of a screw is to melt and feed raw material from the feeder to the die, but it also homogenizes, compresses and pressurizes the material.

Screw Extruder – A machine comprised of a barrel with a temperature control. It houses one or more rotating screws, which pass plastic materials from the feed aperture and move them in the form of melt under pressure through a die.

Take-up – An apparatus for reeling extruded material.

Thermoset – A term that refers to the family of materials that can be melted only once during the original processing and cannot be reprocessed after the original part is made.

Thermoplastic – Any material, such as polyethylene, Santoprene and ABS, which can be remelted and reprocessed without considerable loss of properties or scrap loss.

Torpedo – An apparatus at the discharge stage of the screw for finishing homogenizing and blending of the melt.

Trunking – An extruded PVC-U channel used to contain and protect pipes or cables.

Vacuum Sizing – A procedure utilizing a sizing die with a vacuum applied to the outer surface of the extrudate.

Vinyl – A generic term for PVC, it is one of various compounds of ethylene that are polymerized to form resins and plastics (e.g. polyvinyl or polyethylene plastics).