There are hundreds of different plastic resins available for the injection moulding process, so narrowing down your options can be tricky. This article provides a starter guide on how to choose a material for your plastic product and a list of most commonly used injection moulding resins and their typical applications.
When you’re designing a part for injection moulding, it’s important to choose a suitable material. Here are the five basic steps we recommend following to select the right plastic for your custom product:
A good place to start is by asking yourself the following questions:
While a product’s structural integrity and functionality are paramount, you shouldn’t undermine aesthetics. In the world of product design, the look and feel of a product play a crucial role in its market appeal. Consider that some plastics are better suited for achieving certain SPI textures or may be more compatible with specific paints, coatings, or adhesives.
Understand how different materials will affect the injection moulding process — as different resins behave differently during moulding. Make sure to consider factors such as melt flow characteristics, shrinkage rates, cooling times, and tooling requirements. Neglecting these aspects can lead to inefficiencies in production or unexpected costs.
Use the guide above to identify candidate materials and narrow down your options to the materials that fulfil all (or most) of your design requirements. But also make sure to seek input from an experienced injection moulding expert like HLH Rapid. Plastic injection moulding is a complex and specialized process, so it’s advisable to consult with someone skilled in the area.
Before finalizing your choice of plastic, it’s essential to conduct material tests to ensure that it will perform well under the intended conditions. This may include stress tests, chemical resistance tests, or other evaluations relevant to your project. These tests will ensure that the chosen material meets the performance and durability requirements for your application and help avoid costly mistakes down the road.
When it comes to injection moulding transparent parts, PMMA is the top choice. It has high gloss, good abrasion resistance and performs well in outdoor applications since it cannot corrode and is resistant to UV light and moisture. Overall, it is an excellent alternative to glass and can be moulded to achieve complex shapes for a wide variety of applications.
PMMA injection moulding applications:
PC is a good alternative to injection moulding PMMA. While acrylic can produce exceptionally clear results, PC offers superior scratch and impact resistance. This makes it favoured for applications where high strength and clarity are crucial like protective equipment, safety goggles, and bulletproof glass.
PC injection moulding applications:
ABS is a lower-cost engineering grade plastic found in many commercial products. It is known as a ‘general-purpose’ plastic because it offers a good balance of mechanical properties, ease of processing, and affordability, making it suitable for a wide range of applications. ABS is also compatible with colorants and has multiple options for various textures and surface finishes.
ABS injection moulding applications:
PP is another low-cost injection moulding material option. It has high impact resistance, is water-resistant, flexible, and resistant to acids. This versatility makes it one of the most widely used plastics in the world. It’s worth noting that PP has a relatively slippery surface and is resistant to glue, which can make bonding parts with adhesive challenging.
PP injection moulding applications:
PA (nylon) is a strong, durable thermoplastic and an excellent alternative to metal components in high-temperature environments. There are many different types of Nylon grade available, the most common grades used in plastic injection moulding includes PA6, PA 6/6, and PA66. It’s worth noting that nylon can be susceptible to degradation from sunlight exposure and has limited resistance to strong acids and bases, but additives and fillers can help with these shortcomings.
PA injection moulding applications:
PEEK is a high-performance engineering polymer with exceptional thermal stability and excellent mechanical properties and resistant to wear, making it ideal for lightweight aerospace components. It is also a versatile moulding resin ideal for applications requiring sterilised equipment or electrical insulation. One of the main drawback is that it is higher in cost compared to other injection moulding materials.
PEEK injection moulding applications:
POM is an high strength engineering thermoplastic with excellent fatigue resistance and good chemical resistance. Its low coefficient of friction and outstanding wear resistance, make it a go-to choice for moving components in pumps and valves and other mechanically stressed components.
POM injection moulding applications:
TPE is a blend of plastic and rubber materials. It has shorter mould cycles and supports two-shot injection moulding, making it easier and less expensive to mould than rubber. Although it has a tendency to lose rubber properties at high temperatures, it generally maintains good impact resistance, making it a valuable material in various applications, especially where flexibility and durability are required.
TPE injection moulding applications:
TPU is a type of thermoplastic elastomer (TPE) which has rubber-like elasticity but can be injection moulded to produce a harder rubber with high durometer. It has the ability to withstand extreme temperatures, as well as its resistance to chemicals and abrasion. TPU is also available in commercial, medical, and industrial grades, making it a versatile material for a range of applications.
TPU injection moulding applications:
PC-ABS plastic is one of the world’s most widely used engineering thermoplastics. It is a combination of PC and ABS that boasts the high processability of ABS, making it easy to work with, while having the heat and impact resistance and excellent mechanical properties of PC material. In addition, PC-ABS holds its dimensional stability over time.
PC/ABS injection moulding applications:
PC-PBT is a type of engineering plastic that offers a high strength-to-weight ratio. It is a combination of PC and PBT that boast the high toughness and dimensional stability of PC and good chemical, heat resistance, and high processability of PBT material.
PC/PBT injection moulding applications:
If you’re unsure of which plastics or grades to use for your project, our engineering team is always available to give recommendations and help you with your decisions. Simply send your CAD and project details to our contact form here to get a FREE quote and start your project review.
