7 Types of Injection Molding Materials

Injection molding is one of the most preferred manufacturing processes for fabricating a wide variety of plastic products, from simple household articles to highly complicated parts for automotive and medical applications. Injection molding is a process in which molten material is injected into a mold whereby it cools and solidifies in the desired configuration. One of the main advantages of this procedure is in producing custom machined parts to precision, consistency, and efficiency.

This is the reason why not all injection molding materials are the same; the selection of material is intimate to the strength, flexibility, durability, and the overall quality of the resulting parts. Let's take a look at seven types of commonly used injection molding materials and what makes each of them different.

1. Polypropylene (PP)

Polypropylene is among the plastics that are most extensively involved in the injection molding process, mainly due to its versatility, low cost, and excellent chemical resistance properties. It is lightweight and very durable, while at the same time moisture-repellent, which is suitable for use in foods, medicines, and automotive products. Further, it is highly flexible, a factor that aids in the prevention of cracking when subjected to stress. On the other hand, it has relatively poor heat resistance properties and this limits its application in high-temperature uses.

2. Acrylonitrile Butadiene Styrene (ABS)

Typically machined custom ABS is a strong and impact-resistant material. ABS is used in delicate and durable applications, like automotive parts, electronic housings, or LEGO bricks. ABS is indeed strong in resisting stress and has a very glossy finish, which is pleasing to the eye in consumer products. On the downside, it is not very UV or temperature resistant, so it will likely suffer degradation if used outdoors in harsh conditions over long periods.

3. Polyethylene (PE)

There are many forms of polyethylene like high-density polyethylene (HDPE) with strong and rigid characteristics for products like milk jugs, piping, and storage containers. LDPE is more flexible and is used for plastic bags and squeeze bottles. Both types are equally resistant to moisture and chemicals, making them compatible for food packaging and industrial applications. PE's downside is that it has lower resistance against heat compared to other plastics.

4. Polycarbonate (PC)

Polycarbonate, a high-impact strength material, is known for its clear and strong visibility qualities. Safety glasses, medical devices, and even bulletproof windows make extensive use of this material; it puts up well against extreme conditions with clarity. Hence, it becomes the most preferred material for a product that is both strong and transparent. Although the PC is very strong, it is also costlier than other injection molding materials and is prone to scratches.

5. Nylon (Polyamide – PA)

Nylon is a strong and durable material used for custom machined parts that require a high degree of resistance to wear and tear. It exhibits excellent mechanical properties, which include toughness, flexibility, and resistance against abrasion and chemicals, making it widely used in automotive components, gears, and industrial machinery. However, it tends to absorb moisture, which may lead to the loss of dimensional stability over time. Therefore, it is important to properly store and treat the nylon to maintain its properties.

6. Polystyrene (PS)

Polystyrene is a material: thin, light, and versatile, used in many applications. It is mainly classified into two general types: general-purpose polystyrene (GPPS) and high-impact polystyrene (HIPS). GPPS is colorless and brittle, commonly used for items such as disposable cutlery and CD covers, while HIPS is tougher and used for appliance casings and toys. Easy to mold, polystyrene is not the heavyweight champ by far if resilience is what is desired; it is rather easy to break under stress.

7. Polyether Ether Ketone (PEEK)

PEEK represents an ultra-high performing engineering plastic with extraordinary strength, heat resistance, and chemical resistance. The material is particularly suited for advanced applications in aerospace, medical implants, and industrial machinery. Because it can withstand extreme temperatures and very hostile environments, it remains the material of choice for high-performance demanding industries. High performance comes at a fairly steep price, making PEEK difficult to find outside certain niche applications, such as consumer products.

Choosing the Right Material for Injection Molding

The right material for the injection molding process must be chosen based on the specific requirements of your product. If you need custom machined parts that require high strength and durability, ABS or Nylon could be the best materials. On the other hand, if flexibility and resistance to chemical action are most important, Polypropylene or Polyethylene could be suitable options. Finally, for higher-performance applications, Polycarbonate and PEEK are probably list-toppers, but priced very much higher than the other alternatives.

Understanding the advantages and limitations of each material helps manufacturers to optimize production while ensuring the best quality of their products. With the proper choice of material, injection molding remains one of the very efficient and reliable methods by which large numbers of plastic components are fabricated.

Contact us today to find out more about our different injection molding projects and how we can assist the manufacturing of different components for your industry. Let us build something incredible together!

 

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