Understanding the most common types of plastic resins used in Injection Moulding


Understanding the most common types of plastic resins used in Injection Moulding

Authored By: SDI Plastics

Plastic resins are the fundamental building blocks of producing plastic products and form the foundation of the plastic injection moulding process. They are typically derived from petroleum or natural gas through a process called polymerisation. Plastic resins are widely used in various industries, including plastic injection moulding, due to their versatility, durability, and cost-effectiveness.

In this blog post, we will explore the meaning of plastic resin, discuss the most common types of plastic resins used in injection moulding and highlight the advantages of using high-grade performance plastics in the manufacturing process.

Understanding plastic resin

Plastic resin refers to a raw, polymeric material in a solid or liquid form that can be melted, shaped, and cooled to create plastic products. Resins possess different physical and chemical properties depending on their composition, molecular structure, and processing methods. These characteristics determine the resin’s suitability for specific applications, including injection moulding.

Plastic Resins Used in Injection Moulding

Plastic resins used in Injection Moulding

Injection moulding deploys a wide range of plastic polymers. The resins have unique properties that make them ideal for certain product types that need to be produced.

The following are popular plastic resin types used in injection moulding manufacturing:

1. Low-Density Polythene (LDPE)

This plastic resin is resistant to both moisture and chemicals. It offers excellent strength, chemical resistance, and impact resistance. It is also less expensive than other plastic resins, making it highly cost-effective. Commonly used for rigid containers, computer components, pipes, and automotive parts.

2. High-Density Polythene (HDPE)

In the field of food packaging, High-Density Polythene outperforms the majority of plastic resins. This resin provides flexibility, moisture resistance, and good electrical insulation. Its high tensile strength makes steel challenging to break or fracture.

HDPE is the plastic material of choice when strength, heat resistance, and durability are required. Because of their excellent heat resistance, they are ideal for producing kitchenware, water bottles, packaging films and coatings.

3. Polypropylene (PP)

There are numerous advantages to using this Polypropylene (PP), ranging from chemical and electrical resistance to high elasticity. It also has a high melting point, making it helpful in creating plastic parts exposed to high temperatures.

There are two types of PP;
Polypropylene Homopolymer, which offers high stiffness, heat resistance, and chemical resistance. This type of plastic resin is most commonly used for automotive parts, appliances, and consumer products.

The second type is Polypropylene Copolymer, which provides improved impact resistance, clarity, and flexibility. Polypropylene is a safe material for making food containers and has packaging applications in the food and beverage industries. This is most suitable for applications like packaging, toys, and household goods.

4. Polystyrene (PS)

Polystyrene (PS) is a widely used plastic resin known for its versatility, affordability, and excellent electrical insulation properties. It is derived from styrene monomers through a process called polymerisation. Polystyrene can be processed into two main types: General-Purpose Polystyrene (GPPS) and High-Impact Polystyrene (HIPS).

Polystyrene is favoured in injection moulding due to its ease of processing, good flow properties, and compatibility with various manufacturing techniques. It can be moulded into intricate shapes with tight tolerances, making it suitable for producing intricate and detailed products.

One notable characteristic of polystyrene is its susceptibility to degradation when exposed to heat, UV radiation, and certain chemicals. This can limit its applications in outdoor or high-temperature environments. However, the addition of additives, such as UV stabilisers and flame retardants, can enhance its performance and broaden its range of applications.

High-Impact Polystyrene (HIPS) usage is popular in industries such as electronics packaging, appliances, toys, and consumer goods. It is also used as a structural material in the automotive industry, particularly for instrument panels, interior trim, and exterior body parts.

5. Polyamide (Nylon)

Polyamide, commonly known as Nylon, is a versatile plastic resin with numerous benefits. It exhibits excellent strength, toughness, and resistance to abrasion, making it ideal for applications requiring durability and wear resistance.

Nylon finds extensive use in industries such as automotive, aerospace, textiles, and consumer goods. It is utilised for manufacturing components like gears, bearings, bushings, and various structural parts due to its high mechanical properties and ability to withstand harsh operating conditions.

6. Polycarbonate (PC)

Polycarbonate (PC) is a highly advantageous plastic resin. It offers exceptional transparency, impact resistance, and heat resistance. PC is widely used in industries such as automotive, electronics, construction, and medical equipment. Its remarkable properties make it ideal for manufacturing safety glasses, automotive headlights, electronic display screens, protective equipment, and durable structural components that require clarity and robustness in challenging environments.

7. Acrylic (PMMA)

Acrylic, also known as Polymethyl Methacrylate (PMMA), is a versatile plastic resin known for its transparency, impact resistance, and weatherability. Acrylics, like PC resin, are translucent. It serves various industries, including automotive, architecture, signage, and lighting. PMMA’s benefits include excellent optical clarity, UV resistance, and ease of fabrication. It is widely used for manufacturing transparent windows, skylights, lighting fixtures, display panels, and protective covers, thanks to its aesthetic appeal, durability, and ability to transmit light effectively.

8. Acrylonitrile Butadiene Styrene (ABS)

Acrylonitrile Butadiene Styrene (ABS) is a highly valued plastic resin in injection moulding. It combines acrylonitrile, butadiene, and styrene monomers to offer excellent impact resistance, strength, and heat resistance.
ABS’s superior processability allows for intricate moulding with sharp corners and complex geometries.

It finds applications in automotive, electronics, consumer goods, and construction industries, providing durability, electrical insulation, and aesthetic appeal for products such as automotive parts, electronic enclosures, appliances, toys, and construction materials. ABS’s versatility, mechanical properties, and ease of processing make it a preferred choice for producing reliable and high-performance plastic components.

9. Polyetheretherketone (PEEK)

It has a broad spectrum of acceptance due to its high resilience to any chemical attack. This PEEK’s resilience to aqueous and heat degradation is another advantage.

PEEK resin is one of the most durable and is used in the automobile industry to make compressor plates, piston parts, and pumps because it is chemically robust and employed in the chemical processing sector and liquid chromatography columns.

10. Polyoxymethylene (POM)

POM is useful in any industry that requires dimensional stability due to its good colourisation qualities, minimal heat distortion, and low moisture absorption. It is used in the automotive sector, plastic gear manufacturing, and the food and beverage industries.

It has low friction, hardness, chemical resistance, and wear and tear resistance. Its ability to reduce friction makes it ideal for manufacturing pumps and valve arts. The toughness of this plastic resin benefits guitar picks, fasteners, and buckles.

11. Thermoplastic Polyurethane (TPU)

Thermoplastic Polyurethane (TPU) is the plastic resin of choice when flexibility is required in the manufacturing process. TPU is a highly versatile plastic resin known for its flexibility, durability, and excellent mechanical properties. TPU offers benefits such as high abrasion resistance, chemical resistance, and elasticity. It serves industries such as automotive, footwear, sports, and electronics. TPU is used for manufacturing applications that require flexibility, such as automotive seals, hoses, footwear soles, sportswear, and electronic device cases, due to its ability to withstand demanding environments and provide reliable performance.

The advantages of using high-grade performance plastics in Plastic Injection Moulding

It is vital to use the right type of plastic resin for producing products. There are many factors involved, and consideration must be given to factors such as the design aesthetics, durability, flexibility, colour and the industry the product is being delivered for.

Below are the advantages of using high-grade performance plastics in injection moulding.

  • Enhanced product quality: High-grade quality plastics ensure consistent performance, resulting in superior finished products with precise dimensions, excellent surface finish, and enhanced mechanical properties.
  • Improved durability: High-grade quality plastics exhibit better resistance to wear, impact, and environmental factors, enhancing the durability and lifespan of injection moulded products.
  • Cost efficiency: Using high-grade quality plastics reduces the risk of defects, rejects, and rework, leading to increased production efficiency and cost savings in the long run.
  • Design flexibility: High-grade quality plastics offer a wider range of material options, allowing for greater design flexibility and the ability to meet specific product requirements.
  • Enhanced processability: These plastics often exhibit better melt flow characteristics, which facilitate smoother injection moulding processes, reduced cycle times, and improved productivity.

In conclusion

Plastic resins are essential materials in the field of injection moulding, offering versatility, durability, and cost effectiveness. Understanding the various types of plastic resins and their properties is crucial for selecting the most suitable material for specific applications. There is no limit to what may be made using plastic injection moulding, thanks to the wide variety of plastic resins that can be used, and it is critical to remember that each application has unique material requirements when it comes to production.

By utilising high-grade performance plastics and the right plastic resin in injection moulding, manufacturers can achieve enhanced product quality, improved durability, cost efficiency, design flexibility, and enhanced processability.

The selection of high-grade quality plastics ensures consistent performance, reduces the risk of defects and rework and ultimately leads to superior finished products. With these advantages, injection moulding processes can be optimised, resulting in increased productivity, product enhancement and customer satisfaction.

Are you looking for an experienced plastic injection moulding company that understands plastic resins and how to produce high quality plastic injection moulded products?

SDI Plastics is the company for you! You can reach us on (07) 3807 8666.

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