Extrusion

Extrusion is a process where material is forced through a specialized tool called a die to produce continuous products with a consistent cross-sectional profile. This precise shaping method is widely used across manufacturing sectors, including wholesale grille mould production and advanced polymer component development.

Plastics Extrusion

Plastics extrusion is a high-volume manufacturing process in which a polymer material, often mixed with additives, is melted and formed continuously. The raw polymer granules are gravity-fed into a hopper and transferred into a heated barrel by a rotating screw powered by an electric motor.

The screw’s design varies based on the material and the final product requirements. As the polymer moves forward, it is gradually compressed and heated through zones controlled by PID systems. Additional heat is generated by shear friction and pressure, ensuring the polymer reaches a uniform molten state.

The molten plastic passes through a filter screen and breaker plate to remove contaminants before being shaped by the die. This die determines the product’s final geometry. After leaving the extruder, the formed plastic—known as extrudate—is cooled, with methods tailored to its shape and size.

For a broader understanding of related techniques, see our guide on what is plastic moulding and how it works.

What are the Different Types of Plastic Extrusion?

Depending on the die design, various extrusion methods are used to produce distinct plastic profiles. Below are the primary extrusion types widely applied in manufacturing:

1. Tubing Extrusion

Tubing extrusion is primarily used for creating tubes and pipes. During this process, internal air pressure may be applied to maintain the hollow structure. After exiting the die, the extruded tubes are typically water-cooled in a specialized tank to ensure dimensional stability.

2. Blow Film Extrusion

Blow film extrusion produces thin plastic films through continuous sheeting. In this process, the molten polymer is cooled before exiting the die, forming a semi-solid tube that is inflated to achieve the desired diameter and thickness. This method is commonly used to manufacture products like plastic packaging and shopping bags.

3. Sheet Film Extrusion

Sheet film extrusion is applied to produce thicker plastic sheets that cannot be made by blowing. The molten plastic is passed through a flat die and pulled over a series of cooling rolls. These rolls regulate sheet thickness and enhance surface smoothness for industrial and commercial applications.

4. Over Jacket Extrusion

Over jacket extrusion is widely used in wire and cable coating. The wire is pulled through the die’s center and coated with molten plastic. When adhesion between the wire and coating is required, pressure tooling is used; if not, jacketing tooling ensures a smooth, non-bonded finish. This process is vital in electrical and communication cable production.