How to Choose the Right Plastic Injection Moulding Material

There are many materials available for injection moulding, including polystyrenes, polyamides, polypropylenes, polyethylenes and elastomers. Numerous qualities have to be considered to choose the right one for your production run. As well as physical and chemical characteristics, there are also regulatory factors to take into account.

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With so many products and so many features, you’ll need to be systematic to come to the right conclusion. A plastic injection moulding company will answer your questions, but you still need to know the questions to ask.

Physical for Purpose

For example, is it important for the part to be rigid, flexible or even elastic? Consider the weight or pressure it could be subjected to and the temperature range over which its properties must remain stable.

Also ask about the material’s longevity or resistance to the elements as well as how it reacts to oil or chemicals.

Product consistency and critical failure stresses are other questions to ask here. How much post-production shrinkage is tolerable? Would it be better if the product bent or snapped under excessive forces or conditions?

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Depending on your market, branding and livery may be significant issues. Even for mundane functional products, appearance and texture can have surprisingly strong influences on marketing.

Some materials are usefully transparent, but colourant additives are usually available. Others can be coloured post production or even embossed. Additives can also be antimicrobial, antistatic or flame retardant.


With so many chemical variations, costing isn’t always easy. The website provides a chart to give you an idea.


Obviously, contact with food brings a range of controls relating to the material used, its finish and even how it’s packaged. Controls are even more stringent for medical products. Contact with skin can be an allergy issue, and other regulations apply if the product is intended for children.

If you intend to export, you need to check the regulations applied in destination countries and comply with REACH standards.

Fumes during production involve you with health and safety at work regulations. Do you have adequate air filtration, ventilation and dust extraction installed? Fumes and toxic side-products can also continue to reside in products long after production. For example, there has been increasing attention in recent years to the level of volatile organics emitted by many synthetic household products and fabrics.

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