Extrusion: A panoramic view
The term extrusion defines a shaping process used in the plastics and food industries. In the extrusion process, the material is pressed out of a die under high pressure and usually at high temperature. This produces a strand of any length that can be further processed into an end product. Depending on the intensity of the pressure in the extruder, a distinction is made between piston and screw extruders.
Questions & information on extrusion at a glance
Which significance does extrusion have in the industry?
In the plastics processing industry, extrusion with the extruder is now one of the most widely used processes of all. The decisive reason for this is, among other things, high efficiency in the series production of plastic parts. In the food industry, the extrusion process is an efficient method for mass production of food products with a uniform texture. It is also suitable for brittle and soft material.
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What extrusion processes are there?
Extrusion technologies enable the production of different end products, such as films, car parts and pasta. Depending on the material used, the desired end product, pressure generation, temperature and shear forces, a distinction is therefore made between different extrusion processes. As a rule, the temperature during the extrusion process is 60 to 300°C and the pressure is 10 to 700 bar. The following processes are available:
- Cold extrusion
- High moisture extrusion
- Hot extrusion
- Coextrusion
- Profile extrusion
- Film extrusion
What kind of plastics can be processed by extrusion?
Granules or powders of plastic are melted (plasticized) during extrusion. Depending on the application, cooling of a plasticized plastic can also take place via a cooling fan or cooling channel with cooling medium, e.g. water. Some plastics also require additional equipment, such as a fume hood for pumping out gases produced during processing. These materials can be processed during the extrusion of plastic:
- Clay
- Ceramic masses
- Rubber
- Aluminum
- Thermoplastic polymers such as: Polyvinyl chloride (PVC), polyethylene (PE), polyurethane (PUR), polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET), polyamide (PA)
- Thermoplastic compounds made from lignin or corn starch
- Biomaterials such as wood-plastic composite (WPC), polylactic acid (PLA), polyhydroxybutyric acid (PHB), cellulose acetate (CA)
What are the applications in extrusion for plastics?
Via plastics extrusion, numerous products such as sheets, pipes and films can be manufactured in any shape and length. Therefore, many industries use extrusion products. These include in particular the medical technology and automotive industries, but also the furniture, packaging, construction and aerospace industries. Profile extrusion is also widespread. These products are among the most extruded items:
- Tubes and rods
- Man-made fibers
- Door seals
- Sheathings
What are the food applications of extrusion?
In food extrusion, crushed raw materials such as coarse flour are used and, depending on the target product, mixed with, for example, fats, colorants, sugar, meat and water. With the aid of steam, this mixture is cooked and passed through the extruder, in which one or two rotating screws force the materials through a die. Via food extrusion, these products can be manufactured:
- Pasta such as noodles
- Potato snacks
- Textured Vegetable Proteins (e.g. textured soy, meat substitutes)
- Pet food for dogs, cats, fish (kibbles)
- Chewing gum and chewy sweets
- Crunchy bread
- Peanut flips
- Some breakfast cereals
- Rice crispies
- Chocolate flakes
- Caramel
Food extrusion: Extruders & Applications
Pet food extrusion
Perform pet food extrusion flexibly with the compact TwinLab-F twin screw extruder.
Extrude gluten free materials
Extrude gluten free flours . Details on the application and further analysis options.
Which extrusion tooling is available ?
For the production of cables, hoses, pipes and films, extrusion dies with known standards or individually tailored to the customer, are required. In extruders with blown film lines for film production, spiral mandrel dies are found. So-called quill dies are used in the production of cable sheathing or hose production because, unlike the mandrel die, the quill die can be passed through something, such as wire.
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Which components make up extrusion lines?
Extrusion lines refer to the machinery required for the production process, which are arranged one behind the other along a single axis. Components of such an extrusion line are the extruder, calibrating table, haul-off, the cutting unit and the collecting table. The calibration table prevents the deformation of extruded material and the haul-off is necessary for the transport of the material, which is shortened by a cutting unit.
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Extruder peripherals for your extrusion line
Which extrusion dies are available for specific purposes?
Depending on the requirements and specifications, different extrusion dies are needed, because the die in extrusion is used to shape the end product. A so-called wide slot die is suitable for the production of films, sheets or tapes. Single-channel dies can be used together with a coex feedblock for multilayer products, such as paper coated with thermoplastics, cast and stretch films, and any type of film or sheet.
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