What is the function of screw in extruder?

Jan 15,2024

In an extruder, a screw plays a crucial role in the plastic processing or material extrusion process. The primary functions of the screw in an extruder include:

Material Conveyance: The screw's main purpose is to convey and move the raw material (such as plastic pellets) along the barrel of the extruder. The rotation of the screw pushes the material from the hopper towards the die.

Melting: As the material moves along the screw, it experiences increasing temperature and pressure. This leads to the melting of the material, transforming it from a solid state into a molten or viscous state. This molten material is then ready for shaping or forming.

Mixing and Homogenization: The screw design may include elements that promote mixing and homogenization of the molten material. This is important in ensuring uniform properties and composition of the extruded product.

Pressure Build-Up: The screw design contributes to the build-up of pressure within the extruder. This pressure is necessary for forcing the molten material through the extrusion die to achieve the desired shape.

Temperature Control: The screw can also play a role in temperature control by regulating the heating zones along the barrel. Different sections of the barrel may have varying temperatures to optimize the extrusion process.

Metering: The screw is responsible for metering or controlling the flow of the molten material. This is important for achieving consistent extrusion and product quality.

Overall, the screw in an extruder is a critical component that facilitates the transformation of raw materials into a molten state and controls various parameters to ensure a smooth and controlled extrusion process. The design of the screw can vary based on the specific requirements of the extrusion process and the type of material being processed.




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