Understanding Plastic ExtrusionThe Spiratex Company | 6333 Cogswell Rd, Romulus, MI 48174 | 734-992-7229

Importance of Plastic Extrusion

Use of plastic has increased manifold in the daily life. Either it is for packing food material or soft drinks or for industrial piping and other uses, plastic is used extensively in all sectors. Plastic can be given various shapes and sizes conforming to your specific requirements using the plastic extrusion method. This has turned very advantageous for industries as they put great emphasis on consistency of the shape, size and quality of the product.

Plastic extrusion process involves melting plastic and giving it various shapes by forcing it into various dies to give shape of continuous of continuous profiles. This is then cut to various sizes.

Using plastic extrusion process we can get final product with constant cross sections which are perfect for industrial use. Plastic extrusion is a great way of achieving standardized sizes which are easily workable.

…Importance of Plastic Extrusion

…Importance of Plastic Extrusion

• Plastic extrusion is the best way to make low cost plastic products at a faster pace and hence it yields greater productivity too.

• Plastic extrusion method is used for manufacturing products such as piping, plastic sheets, weather stripping, wire insulation tapes, adhesive tapes, etc.

Requirements

Plastic extrusion can be carried out with the help of a simple plastic extrusion machine. The main components of the plastic extruder machine are hopper, barrel, screw drive, and the screw drive motor.

Thermoplastic material is the basic raw material used for the plastic extrusion process. It is used in the resin form which is easy to for loading and melting.

… Requirements

The most common materials used for this procedure are high impact polystyrene (HIPS), PVC, polyethylene, polypropylene, and ABS.

For getting the final desired result or dies are used. Dies are prepared specifically as per the requirement of the shape or size of the final product. The accuracy of the die would decide the finish and consistency of the final product.

The Process

The resins are put in the extruder’s hopper and it is ensured that they contain the proper additives required for the work. In case it lacks proper additives then additive such as UV inhibitors, anti-oxidants, or colorants are also added with the resins

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…The Process

These resins are then passed on to the extruder barrel through the feed throat of the hopper. The barrel has a long rotating screw that forces the resins towards the die.

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…The Process

The resins are subjected to extremely high temperature and pressure in the barrel where they start to melt which is necessary to give them the required shape.

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…The Process

The temperature in the barrel can range between 400-530 degrees Fahrenheit. Most of the barrels have the settings which provide increasing temperature at the farther end so that degradation of the plastic can be controlled.

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…The Process

Once the molten plastic reaches the end of the barrel it is forced through a screen pack and then fed into feed pipe which leads to the die. The screen pack serves as a filtering medium where the contaminants in the molten pipe are removed. The number of screens, its porosity and other factors ensure that the right kind of material under the required pressure is attained which can be put to the die.

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…The Process

The molten plastic is then put into the dies where it cools off, hardens and attains the required shape. For expediting the cooling process the newly formed plastic is given sealed water bath. For plastic sheeting extrusion cooling rolls are used in place of water baths.

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Importance of Maintaining the Temperature

Temperature plays a very important role in plastic extrusion process. Maintaining the correct temperature level and melting rate is very important for smooth fluidity of the plastic resins. It is important for minimizing problems like stress and wrapping of the final product.Monitoring of heaters is very important as they need to be lowered, raised or shutoff as per the temperature requirement from time to time. Cooling fans and cast-in heater jackets also play a very important part in attaining the required extrusion temperature.

Screw Design- An Important Consideration

Screw is the only moving part in the plastic extruding procedure and hence various factors like melting rate, size of the resin, type of raw plastic, and amount of pressure required maintaining uniformity, etc. play an important part in deciding the size, design and diameter of the screw.

Few applications in which materials need to be compounded within the barrel of the extruder a twin screw design may be used for adequate mixing.

Some Specialized Extrusion Procedures

One solution fits all can never be fit for industrial purposes as every process has a definite set of requirements. Some specialty extrusion processes are explained ahead

…Some Specialized Extrusion Procedures

Blow Film Extrusion

This is a process ideal for fabricating plastic films such as grocery and food storage bags.

…Some Specialized Extrusion Procedures

Coextrusion

This process is used for extruding several layers of material at the same time. This may require two or more extruder feeds feeding different type of material at the same into a

single extrusion head.

…Some Specialized Extrusion Procedures

Overjacketing

This is used for coating a material with plastic. It is commonly used for exterior wire or cable

jacketing.

…Some Specialized Extrusion Procedures

Tubing Extrusion

This is used for making plastic tubes. The process is similar to plastic extrusion just pins

or mandrels are used in place of dies for producing hollow plastic tubes.

…Some Specialized Extrusion Procedures

Injection Molding

In this process the molten plastic is injected into the mold which is then allowed to cool and

attain the required shape.

…Some Specialized Extrusion Procedures

Blow Molding

This is a process used for manufacturing hollow objects such as plastic bottles and containers. In this process after injecting the plastic hot air is blown in the mold with pressure so that the

plastic attains the required shape.

…Some Specialized Extrusion Procedures

Thermoforming

This is the process of giving the required shape to plastic sheets by applying high temperature

and pressure.

The Spiratex Company

The Spiratex Company is a leader in custom plastic extrusion, serving customers with production facilities in Romulus and Monroe, Michigan. As apioneer in the extrusion process for UHMW/PE, The Spiratex Company has set industry standards for the global extrusion marketplace.

Visit www.spiratex.com to learn more about The Spiratex Company or to request a free estimate.