The plastic extrusion process is a normally high-volume manufacturing technique. The procedure can be defined as a polymer material that is melted and formed in a continuous process.   

The plastic extrusion process is used to create a wide range of products used in our everyday lives. Some example includes piping, tubing, plastic films, and more.

In this article, we will comprehensively discuss the plastic extrusion process. We will consider the plastic extrusion types, equipment components, and processing.  

Introduce to the plastic extrusion process

A plastic extruder typically consists of four zones:

Feed Zone: In the feed zone, the ¡°flight depth¡± is constant. The term ¡°flight depth¡±  refers to the distance between the major diameter at the top of the flight and the minor diameter of the screw at the bottom of the flight.

Compression Zone: The flight depth starts to decrease in the compression zone. As a result, the thermoplastic material will be compressed and begins to plasticize.

Mixing Zone: In the mixing zone, the flight depth return to be constant. A special mixing element can be placed to ensure the material is completely melted and homogeneously mixed.

Metering Zone: The flight depth in a metering zone is smaller than in a mixing zone. The pressure pushes the melt through the shaping die in a metering zone.

Types of the plastic extrusion process

Depending on the die shape, the plastic extrusion process can create different products. Following, we will discuss the four types of plastic extrusion processes.

Tubing Extrusion

The Tubing Extrusion is employed for the extrusion of tubes and pipes. In the process, air with positive internal pressure can be applied. After exiting the die, the tubes or pipes will be pulled into a cooling tank.

Blow Film Extrusion

The ¡°Blow Film Extrusion¡± is utilized for the production of plastic films tubes through continuous sheeting. The film tube melt will be cooled before leaving the die to produce a semi-solid tube and blown to the desired size and film thickness. In general, the blow film extrusion process is used to manufacture products such as shopping bags.

Sheet Film Extrusion

The ¡°Sheet Film Extrusion¡± is used for plastic sheets or films that are too thick to be blown. After exiting the die, the sheets will be pulled, cooled, and regulated through a series of cooling rolls.

Over Jacket Extrusion

In general, the ¡°Over Jacket Extrusion¡± applies to wire coating. In the process, the wire is pulled through the center of the die. If adhesion is required between the wire and the coating, the operator should use pressure tooling. The wire will be covered in molten plastic while in the die and be pressurized when exiting the die. If adhesion is not required, the operator should use jacketing tooling. The wire will be covered by the melt when it exits the die.

How the plastic extrusion process works

Below, we will introduce how the plastic extrusion process works in detail:

1. In the form of granulates, the raw material (polymer) is gravity fed into the hopper and drops on a rotating screw. The rotation of the screw forces the plastic forward through a heated barrel.

2. When the plastic is conveyed through the barrel, the channel or thread of the screw will decrease to compress the plastic.

3. Three or more independent "Proportional Integral Derivative PID" controllers create zones of gradually increasing temperature and heat the barrel.

4. When the plastic melt reaches the end of the screw, the plastic melt is well mixed and pushed through a screen pack to filter contaminants.

5. Finally, the filtered melt is then pushed through the die. The die gives the final product the desired profile and shape.

6. After exiting the extruder, the extrudate is pulled and cooled. The cooling method is dependent on the profile and shape of the extrudate.

How Boyu can help you

Boyu is the right choice to boost the efficiency and quality of your extruded materials with reliable plastic extruders and entire production lines.

Over the years, we have accumulated more than 90 technical patents resulting from our R&D team's efforts to innovate our product lines and technologies. Our products include a full set of systematic solutions from plastic floor extruders to entire extrusion production lines. 

As your reliable partner in the plastic floor industry, we can provide you with high-quality, innovative, and efficient extrusion production lines. Contact us!