Home » Plastic Extrusion » What is an extruder? What are the types?
extruder machine

What is an extruder? What are the types?

The extruder is one of the plastic processing machinery. With the change of temperature and stress during plastic mixing and processing, and the resulting change in the properties of molten materials, the degree of perfection directly affects the quality, output, and quality of plastic semi-finished products or cost.

In this article, we have sorted out the common extrusion molding machines. What are the different characteristics of different models? Take a look at our sharing:

What is an extruder in manufacturing?

“Extruder” also known as “Extrusion Line”, is a mass production process that melts plastic through and forms a continuous profile. Products produced by extrusion include tubing/piping, weatherstrips, fences, deck railings, window frames, plastic films and sheets/door panels, thermoplastic coatings and wire insulation.

And “Extrusion” means that the material passes through the action between the extruder barrel and the screw while being heated and plasticized, it is pushed forward by the screw, and continuously passes through the tooling or die to make a processing method for various cross-section products or semi-products.

How to choose the extruder?

The extruder is generally set as a unit, and there are many equipment components. The price is relatively high. Therefore, when purchasing an extruder, you must pay attention to the following points:

  1. Identify the manufacturer. There are many manufacturers producing extruders, which causes some confusion for customers who want to buy extruders. Which one is better? The most important thing for customers is to identify powerful manufacturers.
  2. Look at the factory. Before buying the extruder, it is best to visit the factory in person. Powerful manufacturers, the scale of the factory is relatively formal, the factory area is relatively large, and the factory is fully equipped.
  3. Listen to word of mouth. The manufacturer can be allowed to provide several customers who buy equipment. Contact them yourself and ask how the plant’s equipment is. The best experience is what other customers have used.
  4. Compare prices. When purchasing machinery and equipment, it should not be purely based on low price, but should be combined with quality. Remember not to covet cheap equipment.
  5. Have the instruction manual of the extruder and whether there is follow-up after-sales service, maintenance of the extruder, etc.

What are the types of extruder?

Classification 1: Screws

Single screw extruder

The single screw extruder is the basic model and works by feeding plastic material (granules, flakes, or powder) from a hopper into the extruder barrel. The material is gradually melted by a single screw and an agitated mixture produced by heaters designed along the feed tube. The molten plastic polymer is then extruded from the die to produce the plastic polymer in the desired finished appearance shape.

co-rotating twin screw extruder

The plasticizing capacity of the twin-screw extruder is better and faster. Granular material stays in the extruder longer than a single-screw extruder, slowing down production time. So that plastics, additives, and fillers can be fully and evenly dispersed, stirred, compressed, and kneaded, and higher quality composite materials can be obtained.

counter-rotating twin screw extruder

Counter-rotating twin-screw extruders generally use two screws of the same size but opposite screw directions. To strengthen the mixing effect, the screw adopts the structure of different thread head numbers, variable pitches, and mixing chambers. Compared with the co-rotating twin-screw extruder, the shearing is softer, the conveying capacity is strong, and the decompression capacity is strong.

Classification 2: Extruded finished product

Blown Film Extruder

blown film extruder

The blown film extruder machine line is a device that heats and melts plastic particles and blows them into films. Film blowing machines can be divided into many types according to the application materials, such as PE, POF, PVC, and so on.

Extended application:
Plastic Film Side Sealing Machine


The plastic film side sealing machine is the post-processing machine of the film extruder and always with cutting machine, which can make the plastic film into various shapes of folds and pockets, and make many types of plastic bags.

Plastic Bag Making Machine

t shirt bag making machine

With plastic packaging bags as the main product, the finished product extruded from the film: plastic bag making machine, is a machine that makes various plastic packaging bags by heat sealing and cutting, and its processing range is various sizes.

Profile Extruder

plastic profile extrusion line

Pipe Extruder

pipe extruder

The pipe making extruder machine  is to use an extruder with a longer screw to achieve better plasticizing capacity and more consistent and continuous extrusion of the finished product.

Tube Extruder

pe tube extruder machine

The tube co-extrusion line is an extruder designed to add materials that can enhance the characteristics of the pipe when producing the pipe in a co-extrusion method.

Zipper Exrtuder

zipper extruder

In addition to the die design of the extruder, Zipper extruder for zipper bags making machines also requires high speed and stability in production. It is necessary to consider the cooperation of the cooling system, such as ice water constant temperature system, vacuum high-pressure air drying, and clamp the chain at the appropriate time. The effect of the clip chain is extruded out of the finished product.

Recycling Pelletizing Extruder

recycling pelletizing extruder

The waste plastic recycling pelletizing extruder is specially designed to recycle PE (HDPE, LDPE, LLDPE) and PP packaging materials through an extrusion system, transmission system, and heating and cooling system. The regenerated granulation of various recycled plastics is made into plastic pellet raw materials.

Frequently Asked Questions about Extruders

How much does a plastic extruder cost?

The extruder is not cheap, but if there is always a demand for extrusion, you can purchase a high-precision plastic extruder depending on the company’s budget and extrusion difficulty. In addition to avoiding an OEM cost, you can extrude products more flexibly and greatly improve the connection rate. Single quantity, amortizing the production cost, in the long run, is a good way to reduce the cost.

How to stabilize the quality of the extruder?

In the daily production of extruders, various quality problems are often encountered. The following is a list of three points for us, the common plasticizing problems and solutions in the production of extruders:
The surface is powdery, dull and granular.
Causes: The temperature of the body is not enough; the temperature of the nose is too low; the speed of the screw machine is too fast.
Treatment method: Appropriately increase the temperature of the extruder body; appropriately increase the temperature of the machine head; slow down the speed of the extruder.
Matte surface.
Causes: The temperature of the machine is too low; the wire diameter is too small; the mold sleeve is too large.
Treatment method: Properly increase the temperature of the machine head; measure the outer diameter, and select the corresponding mold sleeve according to the wire diameter.
There are bubbles on the surface.
Causes: The extruder product has water and oil; the plastic is wet; the temperature is too high.
Treatment method: clean up water and oil stains for reproduction, use a preheater to heat; dry the plastic; appropriately lower the temperature of the extruder.

The difference between extrusion molding and injection molding

Extrusion and injection molding are two methods of plastic processing. Extrusion is mainly used to produce materials that can be continuously produced such as sheets, pipes, bars, special-shaped materials, and films. The injection molding process is to intermittently produce one-mold plastic parts.