Plastic Extrusion

How Does Plastic Extrusion Work?

01 Design & Preparation

Several critical factors must be addressed when designing the tool and die for plastic extrusion. Flow balancing is a must to ensure that the molten plastic flows evenly through the die. Uniform wall thickness and avoiding sharp corners are also important. They must be slightly smaller than the desired product dimensions because the plastic expands as it cools. Special dies with internal pins (mandrels) are used to create hollow extruded profiles.

02 The Extrusion Process

The feed process for plastic extrusion is similar to injection molding: Plastic pellets are fed into a heated barrel with a rotating screw. The melted material is forced through the die and then cooled by water or a series of rollers. Uniform cooling is critical to prevent warping and shrinkage. A “puller” maintains tension and ensures consistent line speed during the cooling process.

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03 Post-Production

Common post-production steps for plastic extrusions include surface finishing (such as painting, surface texturing and labeling), mechanical modifications (drilling, punching and milling) and joining (via ultrasonic welding or liquid adhesives). In short, both the extruding and finishing processes can be highly tailored to meet the customer’s needs.

Is Plastic Extrusion A Fit For Your Needs?

Advantages

Cost-Effective

The continuous plastic extrusion process combines high production efficiency with minimal material waste. It is a cost-effective choice for large-scale manufacturing runs.
Consistent Quality

Plastic extrusion lends itself to consistency – especially uniform material flow and proper sizing. This results in smooth surface finishes and high quality across long production runs.
Flexibility

Custom-designed dies enable the production of complex cross-sections. This helps manufacturers meet specific design and application requirements.
Versatile Materials

A wide variety of thermoplastics can be used – with each offering different properties such as strength, flexibility or UV resistance. Products therefore can be tailored to a variety of applications, both indoor and outdoor.

Disadvantages

Initial Costs

Creating custom dies and tooling involves significant upfront investment. This makes plastic extrusion impractical for prototyping or short production runs.
Limited Shapes

Extrusion is best suited for parts with uniform cross-sections. Complex or irregular shapes with varying profiles are better suited to molding or machining methods.
Shrinking and Swelling

Plastic materials can expand when leaving the die – and contract during cooling. Achieving extremely tight tolerances can be challenging.

What Industries Are The Best Fit For Plastic Extrusion?

Plastic extrusion supports multiple industries through its long-run efficiency and uniform properties.

Construction

Plastic extrusion is used to make pipes and tubing for plumbing, drainage systems and electrical conduit. Other common products include window and door frames, deck planks and siding.

Automotive

Extruded plastics are used for weather seals, gaskets, interior trim and protective coatings for wires and cables. These parts provide durability and excellent resistance to heat and moisture.

Consumer Goods

Plastic extrusion is used to make many household items like storage containers, window blinds and decorative trim.

Medical

Plastic extrusion is essential for producing medical tubing, catheters and components. Its ability to create smooth, sterile and uniform products makes it ideal for healthcare.

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