Common Plastic Injection Molding Materials

Intro

As you might already know, injection molding is one of the best ways to mass-produce parts at affordable prices. It’s common to have per-unit costs of just a few cents for products that you can sell for dollars. In injection molding, plastic is the preferred material.

In this guide, we’ll dive into some of the most common plastic injection molding materials. We’ll explain what they are, why you might pick them, and some advantages of using each particular material.

Polycarbonate (PC)

Believe it or not, PC is used to make bulletproof glass across the world. As such, it’s a very strong material that’s naturally see-through. 

It’s about 250-times stronger than standard glass, and just as transparent. On top of that, it’s a lot lighter and easier to work with.

In injection molding, PC parts can hit tight tolerances very reliably. They can also be machined and finished afterwards with relative ease, making PC a versatile option.

Thermoplastic Elastomers (TPE)

TPE parts are naturally flexible, thanks to their unique blends of plastic and rubber. Even though the part is rubber-like after getting injection molded, you would treat a TPE just like any other plastic. 

Compared to a comparable liquid silicon rubber (LSR), TPE is a lot easier to work with and less expensive. 

Since TPE can elongate so well, it makes the injection molding process easier. These parts are faster to make but a little more expensive than other plastic options.

This material is also more eco-friendly. A typical injection molding facility can recycle TPE parts a number of times, up to about six times altogether. With less waste and more recyclability, you can save money on bulk purchases since scrap parts can be reused.

Nylon Polyamide (PA)

Nylon polyamide is a synthetic material that is very heat-resistant and resilient. In the field, a Nylon part is abrasive-resistant and has great long-term durability and fatigue resistance.

In injection molding, these properties make the material a little more difficult to work with. We have to carefully design the tooling and watch for shrinkage while running the molder. Regardless, the parts you get from us will be high-quality and a great option for long-term use in your operation.

Acrylic (PMMA)

Acrylic is very similar to PC on paper, but with some big strength and cost differences. Acrylic is a less-strong version, but it’s still much stronger than glass and easier to work with. Like glass, PMMA is also transparent.

It’s lightweight and shatter-resistant, which is a big benefit. During injection molding, Acrylic can be held to tight tolerances repeatably. In the field, PMMA can be used to support a load without failing, and it doesn’t degrade in wet environments.

In addition, Acrylic doesn’t contain any BPA, making it a food-safe material in most applications.

The potential downside is that PMMA is known to crack under large loads, and the material is more prone to scratching. However, it’s a less expensive, less strong version of Polycarbonate that offers a lot of the same benefits without breaking the bank.

Acrylonitrile Butadiene Styrene (ABS)

ABS is a style of “engineered” plastic. That means that the plastic is synthetic and built to serve a very specific purpose. In this case, ABS is used as a strong, rigid material option. 

It’s fairly inexpensive and offers some great color options. The finish is typically shiny and attractive, making it a popular choice for commercial goods.

From a materials perspective, ABS deals with heat, oil, fading, and heavy loads fairly well. The problem is that ABS doesn’t perform very well in wet environments, and it is known to wear away when exposed to high friction. 

ABS is very easy to work with and fills injection molds well, allowing for tight tolerances and high precision. We offer a number of different ABS options in-house, allowing you to fine-tune the color and have the final product look perfect without any finishing steps required.

Polyethylene (PE)

Across the board, polyethylene is the most commonly-used plastic in the world. The densities can be customized so you can hand-pick a material selection based solely on its density (which affects the weight of the part).

It’s great at resisting moisture and chemicals, making PE a versatile plastic choice. They can be completely see-through or colored to any color of your choice. You’ll commonly see PE used in children’s toys, since it’s an inexpensive option with good material properties.

It’s the same plastic used in water bottles and milk jugs (though they don’t use injection molding, they use blow molding).

Conclusion

If you’re in the market for mass-produced plastic parts, injection molding might be the right choice for you. We hope that our quick definitions of some of the more popular plastic injection molding materials will help you make your decision.

If you need any more help with material selection, you can talk to our experts at Rapid Axis. In addition, feel free to reach out for a free quote today and get started. 

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