Plastic Extrusions

About Plastic Extrusions and Custom Plastic Extrusions Including: Plastic Channels, Plastic Rods, Plastic Sheets, Plastic Extruders & Extruded Plastics.

Extruded plastic is plastic that has gone through an extrusion process. In this continuous process, thermoplastic resins or plastic polymers are melted, heated and pumped. Molten plastic material is pulled through a calibration system, which includes a die. The die shapes the plastic into the desired shape, or profile. Single- or twin-screw plastic extruders use one or more internal screws in a barrel to melt, mix and push the melted plastic material through the die. This plastic extrusion process shears material between the root of the screw and the wall of the barrel that surrounds it, creating frictional energy that heats and melts the substance as it moves down the barrel. The barrel is also heated electrically to provide the necessary heat to melt the plastic material. A high intensity mixer is another type of plastic extruder.

In sheet plastic extrusions, plastic powder or pellets are cut into sheets or rolls. The plastic sheets are then thermoformed, a plastics extrusions process in which they are re-softened in ovens and then brought into contact with a mold surface by either air pressure or vacuum. The mold determines the inside or outside shape of the part, as it comes into contact with only one side of the softened plastic. The sheet extrusion process can form extremely large sheets, up to and exceeding 2” thick and as wide as 30 ft, which allows the production of very large parts on an economical basis. Two or more plastic extruders can be used to co-extrude sheet products to produce multi-layer structures with distinct layers of plastic polymers. This plastic extrusion process adds functionality and improves the cost performance ratio of the end extruded plastic products.

Extrusion blow molding is used to produce plastic bottles, such as milk jugs and shampoo and bleach bottles. This plastic extrusion process utilizes a die similar to that used for making plastic pipes. Plastic pellets are fed into a blow molder, which is the hopper of the machine. A screw, located inside a heated barrel, pushes forward the softened plastic, which is then forced through a circular die, forming a plastic tube called a parison. Inside a hollow mold, the parison is clamped and inflated from within by pressurized air. The plastic bottle is then ejected and sent on to trimming, printing and filling stations.

Many different types of plastics can used in plastic extrusions, and each has its own advantages. High impact styrene (HIS) has a uniform matte finish after extrusion, is a cost effective material, can be easily colored and has good impact resistance. HIS plastic extrusions are suitable for indoor applications and may have a UV inhibitor added. Rigid vinyl (R/PVC) is moderately priced, tough and versatile, provides good clarity and is available in clear to opaque colors with a moderately lustrous finish. R/PVC plastic extrusions are used for outdoor and indoor applications. Butyrate (CAB) plastic extrusions provide very good quality of clarity, have good flexural strength and a high gloss finish and are typically used for their clear forms. ABS plastic extrusions are tougher, shinier and higher priced than HIS, though worth the cost, if the properties are necessary. Polyethylene (PE) plastic extrusions are an economically priced and of flexible material that can be coiled or spooled in its extruded form and can be cut in the field. When more rigidity is required for PE, high density formulations are available. Other materials used in plastic extrusions include flexible vinyl (F/PVC), acrylic (also called Plexiglass), SAN, polypropylene (PP) and K-Resin. Suppliers of plastic extrusions may have a number of materials in stock: ABS, acrylic, butyrate, fiberglass, nylon, polyamide, polycarbonate, polyethylene, polyethylene terepthalate glycol, polypropylene, polystyrene, PTFE, polyurethane, urethane and PVC.

Custom plastic extrusions are available in many shapes, including thin film plastic extrusions, plastic sheets, plastic rods, wire plastic extrusions and any other custom plastic extrusions to be configured. Methods utilized to create custom plastic extrusions include hot plastic extrusion, cold plastic extrusion, co-extrusion, dual plastic extrusion, multi-durometer plastic extrusion, hydrostatic plastic extrusion, impact plastic extrusion, pultrusions, reverse plastic extrusion, backwards plastic extrusion and wire drawing plastic extrusion. Hot-working plastic extrusion processes use the good deformability of heated metallic or thermoplastic materials for shaping them.
 

Plastic Extrusions and Custom Plastic Extrusions Image Provided by Petro Extrusion Technologies, Inc.

Plastic Extrusions and Custom Plastic Extrusions Image Provided by Plastic Processors, Inc.	Plastic Extrusions and Custom Plastic Extrusions Image Provided by Preferred Plastics, Inc.

Types of Plastic Extrusions

• Co-extruded plastic is material that is a combination of one or more polymers combined in the extrusion process.
  
• Extruded plastics are made by pouring liquid plastic into dies.
  
• Extruded plastic channels are strips of plastic that are shaped for a specific purpose and cut to length.
  
• Extruded plastic netting is produced in a continuous process resulting in a stable net structure in which the hole size is held constant, unlike a woven or knitted product. Extruded plastic netting is typically utilized in vertical applications such as walls for pens, separation in water, filtration, predator control or barriers.
  
• Extruded plastic profiles are shapes that are formed through the extrusion process.
  
• Extruded plastic sheets are plastic powder or pellets that have been formed into sheet products with a range of thickness from less than 0.010 in. (film) up to and exceeding 2.0 inches, with widths as great as 30 ft. This sheet can be further processed into parts via thermoforming.
  
• Extruded tubing is any tube product that has been made through the extrusion process out of thermoplastic or other rigid, semi-rigid or flexible materials.
  
• Plastic extruders are capable of making sheets, tubes, rods and other molded plastic materials.
  
• Plastic rods are cylinder-shaped components made of plastic materials.
  
• Vinyl extrusions are extruded products that are made of polyvinyl chloride (PVC), including pipes, siding and floor coverings

Common Terms Related to Plastic Extrusions

Adiabatic Plastic Extrusions - Plastic extrusions whose only source of heat is the conversion of the drive energy through the viscous resistance of the plastics mass in the plastic extruders.
 
Back Pressure - The resistivity of molten plastic material to forward flow.
 
Barrel - The part of the plastic extruders encasing the screw or plunger.
 
Barrel Liner - The sleeve forming the inner surface of the plastic extrusions barrel.
 
Calendering - The plastic extrusions 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 fade panels.
 
Compound - Any plastic material prepared for subsequent manufacturing processes, specifically plastic extrusions, 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 plastic extrusions are constantly passed for cooling.
 
Cure - The technique of cross-linking a plastics material.
 
Decompression Section - The section of two-stage plastic extruders in which an increase in screw channel volume occurs.
 
Die - The component on plastics extruders affixed to the plastic extruders 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 plastic extrusions or molding.
 
Extrudate - The product or result of the plastic extrusions 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 plastic extruders barrel
 
Extrusion Coating - A coating technique in which molten plastic feeds directly from plastic extruders dies 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 plastic extrusions 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 screw plastic extruders. 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 plastics 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).