Best Plastics for Injection Molding: A Material Selection Guide

Quick answer: Some of the best plastics for injection molding include polypropylene (PP) and ABS, but China plastic injection molding companies also offer a wider range of thermoplastics, from nylon (PA) and polycarbonate (PC) to polyethylene (PE) and acetal (POM). Ultimately, the right material depends on your part’s requirements, including temperature and mechanical loads. HLH Prototypes is one of the trusted names in injection molding in China and they can make your part from a wide range of high-quality plastics based on your application and needs.

The resin you choose can affect how well your part holds up and meets the tolerances required for assembly. The last thing you want is to choose the wrong material that can result in warped parts and poor fits. So before sending your files to a manufacturer in China for plastic injection molding, use this guide to compare some of the best plastics for your project.

The most common plastics for injection molding

You’ll come across several plastics when planning an injection molding project. Some materials appear more often because they offer properties that suit a wide range of applications.

Plastic	Key properties	Common applications
Polypropylene (PP)	Flexible, chemical-resistant and relatively inexpensive	Consumer products and packaging
ABS	Rigid, impact-resistant and easy to process	Electronics housings and automotive components
Nylon (PA)	Strong, wear-resistant and able to handle heat	Mechanical components, such as gears and brackets
Polycarbonate (PC)	Optically clear with high impact strength	Lenses and medical devices
Polyethylene (PE)	Soft and chemical-resistant, with food-safe grades available	Containers and fittings
Acetal (POM)	Dimensionally stable with low friction	Precision mechanical components

When choosing from these options, figure out what your finished part actually needs to do, from the loads it will experience to the environment where you’ll use it.  This can help you narrow down the options before you send your project to a manufacturer in China for plastic injection molding.

Which plastic suits your part?

A component that stays inside a temperature-controlled enclosure won’t face the same conditions as one sitting outdoors or near a hot engine. Consider asking yourself these questions to help narrow down your options for China plastic injection molding:

Temperature	How hot or cold will the part get?	Some plastics soften at relatively low temperatures, while others can maintain their shape above 200°F.
Chemical exposure	Will the part contact oils, solvents, cleaners or other fluids?	Certain chemicals can weaken or damage some plastics after prolonged exposure.
Mechanical load	Will the part carry a static load, flex repeatedly or experience impacts?	Different plastics respond differently to continuous loads, movement and sudden forces.
UV exposure	Will you use the part outdoors or in direct sunlight?	Some plastics need UV stabilisation to prevent degradation. Standard ABS, for example, can degrade outdoors without it.
Production volume	How many parts do you need?	Common resins can help you save money, especially for larger production runs. However, you should consider engineering plastics when performance is a priority, no matter the cost.
Tolerance	How precise do the finished dimensions need to be?	Your manufacturer needs to account for plastic shrinkage when designing the mould.
Compliance	Does your part need food-contact, medical or flame-rating compliance?	You can rule out certain materials to meet regulatory requirements before production begins.

Choose a plastic based on your application

It’s easier to choose a plastic when you know what your finished part must do instead of comparing a long list of materials.

Take automotive components, for example. Parts under the hood may deal with heat and vibration at the same time. Nylon and POM can handle these conditions better compared to many general-purpose plastics. For exterior parts where appearance also matters, ABS and PC/ABS blends can give you a good combination of surface quality and impact resistance.

Medical and food-contact components come with different priorities. Compliance requirements can quickly narrow your choices. You’ll find PP and PE are available in medical-grade and food-safe variants, but their material grade should match compliance requirements.

Nylon can be a good choice for functional or mechanical parts, but it absorbs moisture from the air. In humid environments, that moisture can make the part swell or change size slightly, which can affect fit and performance.

We can help you choose your plastic

Not sure which plastic to use for China plastic injection molding? Get in touch with our team here at HLH Prototypes so we can review your project and give suggestions based on your design and production needs.

To get started, fill out our online contact form with your details or email us at  FreeQuote@HLHPrototypes.com.