Types of Plastic Extruder

Plastic is an important material in modern industry and everyday life. It is popular in the manufacturing industry for its lightweight, corrosion resistance, insulation, and moldability. Plastic extrusion, as part of the plastics process, is used in a wide variety of applications to produce tubes, sheets, profiles, films, and customized shapes. The process involves the uniform melting of thermoplastic materials.

This article categorizes and describes several common types of plastic extruders, so let’s take a look at them together:

The screw is the core component of a plastic extruder, and the different configurations of the screw are also the key to differentiating between different types of extruders. Below are several common types of plastic extruders categorized according to different screw numbers and configurations:

Single Screw Extruder

The single screw extruder has one screw in the extruder barrel. The plasticized material is melted through the single screw and an agitated mixture is produced by a heater designed along the feed tube and then extruded from the die.

Single screw extruders are simple to operate and low maintenance, but are not suitable for all types of materials and may have limitations in mixing efficiency. Nonetheless, single-screw extruders are commonly utilized in various plastic processing applications, including PE, PP, and PVC.

Twin Screw Extruder

This machine’s compounding abilities enable the material to move between the screws numerous times, preserving most of the polymer and subjecting only a small portion to high-pressure shearing. This superior shear rate and mixing capability is what sets it apart from single screw machines.

Twin screw extruder occupies an important market share by virtue of its excellent performance and wide range of applications. In this article, we will make a further subdivision for the twin-screw extruder:

Intermeshing Twin Screw Extruder: The benefit of the captivating layout is the complete blending and shearing of the material within the apparatus. This design reduces the retention of the material in the conveying section, and in the plasticizing section, the melt state can be reached quickly.

Non-Intermeshing Twin Screw Extruder: The screws do not engage with each other, the degree of compactness is small, and like the single screw machine the conveyability is poor, and the shear force is lower. It is also suitable for high filler material handling because it is not easy to destroy the structure of the material. It is also suitable for high-filler materials because it is not easy to destroy the structure of the material.

Conical Twin Screw Extruder: The spacing between the screws is relatively wide enough, which can provide enough thrust bearing for the material. Low loss, high flexibility, high torque transfer, high self-cleaning ability, and good plasticizing effect are the main advantages.

Parallel Twin Screw Extruder: The two screws are in parallel shape, compared with the conical machine, this design can better convey the material and control the shear. High mixing efficiency, controlled shear, high output, and low energy consumption are its advantages.

Co-rotating Twin Screw Extruder: The screws rotate in the same direction and the threads are designed to engage with each other in corrugated, tapered, and parallel designs. This design provides excellent shear capacity. High material output rate, high melting capacity, good stability, and self-cleaning ability make the coaxial twin screw extruder more inclined to the processing of composite materials.

Counter Rotating Twin Screw Extruder: Two screws counter-rotate, providing a low shear rate and limited mixing ability, making them primarily utilized in the manufacturing of plastic pipes and profiles.

Triple Screw Extruder

The barrel contains three screws that engage with each other, usually in a triangular arrangement. This complex design provides more contact surfaces and flow paths, further improving mixing capacity, shear efficiency, and plasticizing effect. Some composite materials and polymer materials need to achieve an ideal mixing state, the three-screw extruder has obvious advantages over the above types of machines. In addition, another significant advantage of the three-screw is the high output and low energy consumption, under the same conditions the output is twice as much as the twin-screw.

In response to the constant quest for productivity, extruders have evolved from the single screw to the triple screw, and now there are also multi-screw machines available for people to choose from.

Special Types: Two Stage Extruder

The two stage extruder consists of two separate stages, which we can see as a combination of a twin-screw machine and a single-screw machine.

The first stage is mainly used for melting and plasticizing the material. The material is melted by heat under the action of the screw and is initially mixed and plasticized by the shearing action of the screw.

The second stage is mainly used for further mixing, venting, and homogenization. In the second stage, the material is further processed under low shear to ensure that volatiles and gases are fully expelled from the material.

The two stage extruder offers efficient mixing, plasticizing, and degassing capabilities for a wide range of complex and demanding plastics processes.

 

Plastic compounding technology originated in 1870 and evolved from rubber compounding. The introduction of the twin-screw extruder marked a breakthrough in plastic compounding technology. Nowadays, most thermoplastics need to be blended before processing, and plastic compounding has become the most widespread use of plastic extrusion. The process of plastic compounding can be broadly summarized as metering, mixing, plasticizing, separating, and pelletizing.

In addition to the broadest range of applications, the following is a breakdown of several other common uses of plastic extrusion:

Laboratory Twin Screw Extruder

Laboratory twin screw extruders are generally used for small-scale production and research and development of new materials and formulations. The ability to quickly test different formulations and process conditions provides the data and basis for large-scale production.

The upper part of the laboratory twin screw extruder allows frequent replacement and adjustment of screws, barrel segments, and process parameters, supporting a wide range of material and process tests. Highly accurate sensors and control systems allow precise adjustment of parameters such as temperature, pressure, and screw speed. It is usually equipped with detailed data recording and analysis functions to help R&D personnel optimize formulations and processes.

Plastic Pipe Extruder

A plastic Pipe Extruder is generally equipped with a ring die, which is used to extrude the plasticized plastic melt into a hollow pipe. Cooling and shaping are carried out by cooling tanks or spraying devices. A haul-off is provided for uniform stretching and transportation of the shaped pipe.

The sizing sleeve is used to control the outer diameter and roundness of the pipe to ensure the precision of the product size.

Plastic pipe extruder is suitable for all kinds of plastic pipes, such as PVC pipe, PE pipe, and so on.

Plastic Sheet Extruder

Plastic sheet extruders are generally equipped with a flat die to extrude the plastic melt into sheets. Air or water cooling is used for cooling and shaping. A winder is provided to roll the shaped sheet into rolls.

Plastic sheet extruders are suitable for all kinds of plastic sheets such as PP sheets, and PET sheets.

Plastic Profile Extruder

A plastic profile extruder is mainly used for the production of window frames, door frames, decorative strips, cable channels, automobile parts, and so on. The cross-section shapes of these products are complex and varied, with common shapes such as T-shape, L-shape, U-shape, etc. Therefore, the molds need to be customized according to the different cross-section shapes.

The molding device of the plastic profile extruder is complex, and the precise control system can adjust many parameters. Only skilled personnel familiar with the process of mold adjustment and product shaping can ensure accurate molding of complex cross-sectional shapes.

Plastic profile extruders are mostly used in the construction industry, home decoration, industry, and electrical.

Conclusion

With the development of technology and productivity, various types of plastic extruders have been derived. Users need to weigh the advantages and disadvantages of these plastic extruders by themselves to select the one that suits them best.

Above is the introduction of several common plastic extruders, if you want to pick a professional plastic extruder supplier, KAILIDA will be your best choice.

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