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head plastic extrusion

Plastic Extrusion

The Plastic Extrusion Process

Plastic extrusion means or is defined as a manufacturing process in which the raw plastic / raw plastic material is melted and then formed in a continuous profile. Extrusion is a fascinating technology that can be referred to as an “integrated processing technology,” as it combines various unit operations into one system. It is a continuous processing system with the ability to convey, mix, shear, and transform plastic and food materials as they are processed through it.

With this process various products can be manufactured such as:

  • Pipe/tubing
  • Window frames
  • Weather stripping
  • Wire insulation
  • Cereals and pet food

For example, Bausano extrusion lines can produce pipes, window and other technical profiles, pellets/compounds and medical tubes&bags. Bausano is active in plastic extrusion, also known as plasticizing extrusion, this process is a continuous high-volume manufacturing process in which a thermoplastic material -- in a form of powder, pellets or granulates -- is homogeneously melted and then forced out of the shaping die head by means of pressure.

plastic extrusion

Plastic Extruders

The machine which forces the mix through the die is a plastic extruder, and the mix is known as the extrudate. A typical extruder usually consists of seven major components, such as:

  • Feed assembly
  • Extruder barrel
  • Extruder screw
  • Extruder drive
  • Extrusion discharge or die system
  • Heating/cooling system
  • Adequate safety and control facilities

An important part of the extruder is the motor, which provides the energy to rotate the extruder screws. But the first step in raw material processing with Bausano extrusion process is when the raw thermoplastic material is gravity fed from a hopper (top mounted) into the barrel, which is the first part after the feeder of the extruder. The raw material is in the form of small pellets and is generally called resin. Before the material is put in the feeder, it can be mixed with different additives like colorants & UV inhibitors to enhance properties and quality of the raw material.

In the extrusion process, the raw material is subjected to compaction, shearing, particle size reduction, phase transition, and molecular breakdown, because of shear which is generated by the action of the screws and particles of the material rubbing against each other. So, the material once it goes into the barrel and screw it typically changed into a melt form thanks to high pressure, high temperature and shear.

This melt is finally pushed through the die at the end of the screw and barrel, to form the desired shape. The internal temperature varies according to the type of raw material processed. When plastic is extruded from the die, it is fed onto a conveyor belt for cooling, which can be air or water. This phase is very important for the success of the process. At the end of the cooling process some extruders have also end of line equipment like haul-off units or cutters to complete production.

Extrusion systems have evolved over the decades and one of the critical, and most important elements, is the extruders screw.

The screw along with the barrel accomplishes the roles of conveying, mixing, metering, and kneading the raw material in the barrel. The different extruders are distinguished by the number of screws they have. This means that principally two are the types of Extruders, Single Screw Extruders and Twin-Screw Extruders. Single-screw extruders can be classified based on shear capabilities, heat source, screw design (segmented vs solid) while twin-screw extruders are classified into counter-rotating or corotating with intermeshed or non-intermeshed screw systems. The major difference between single- and twin-screw systems, apart from the fact that they have single versus double screws, is that twin-screw extruders have a wide range of operational capabilities in terms of the type of raw materials they can handle and the operating conditions. So Twin screw extruders are more versatile in terms of material processing.

For example, for processing PVC, a Twin Screw is needed due to the characteristics of the material that is harder to process and a Twin screw extruder is more efficient and withstands more difficult materials, because Twins have a better mixing capability. In addition to the two types of extruders available, there isalso the possibility of combining several extruders to produce more complex products and shapes from different materials. This process is called Co-extrusion and involves combining two streams of products in the final die, resulting in the products that have multiple textures. Generally, the end products have an inner core and an outer shell.


Other materials used in extrusion are also Thermoplastic elastomer (TPE), Thermoplastic polyurethane (TPU), Thermoplastic rubber (TPR), Poly (methyl methacrylate) (PMMA)

Additives, such as colorants and UV inhibitors, in either liquid or pellet form are often used and can be introduced into the resin below arriving at the hopper. The use of additives during the extrusion process help to enhance processing characteristics of the polymer or to alter product properties.

Application and Advantages

Extrusion is an efficient way to produce many shapes and is essential in industrial and domestic product applications. Bausano has many years of experience in many different applications, thanks to the personalized solutions offered.
Personalized application sectors:

  • Granules and pellets

  • Pipe for drinking water, sewage, gas transportation and many other

  • Window&doors profiles and technical profiles

  • Medical Tube, Bags and Sheets

  • WPC pellets and profiles

These types of application are made with extrusion thanks to the high advantages of the Extrusion process in respect to other methods. Extrusion is a simple but efficient production process, and the most important advantages are:

  • Low cost per part.
  • Flexibility of operation.
  • Continuous operation.
  • High production volumes.
  • Many types of raw materials can be used.
  • Good mixing (Compounding)

Complementary to Extrusion


Dosing System

Feeding system are an important part of the extrusion process. You have to choose the right system for your desired production.

intelligent automation

Intelligent automation

Bausano's 4.0 Digital Extruder Control to monitor the extruders performance. 


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