Common Injection Moulding Plastics: Properties, Uses & Selection Guide

Injection moulding is one of the most widely used manufacturing processes for producing high-volume plastic components. From automotive parts and medical devices to packaging and consumer goods, the process relies heavily on the choice of material. Each plastic has unique characteristics—such as strength, flexibility, heat resistance, and cost—that determine its suitability for a given application.

Below, we explore the most common injection moulding plastics, their properties, advantages, and key applications.

1. Acrylonitrile Butadiene Styrene (ABS)

Properties:

Tough and impact-resistant

Good dimensional stability

High surface finish quality

Easily coloured and painted

Advantages:

Affordable and versatile

Excellent mechanical properties for structural applications

Common Applications:
Automotive dashboards, power tool housings, consumer electronics, toys (e.g., LEGO bricks).

2. Polypropylene (PP)

Properties:

Lightweight with low density

High chemical resistance

Good fatigue resistance (hinge-like applications)

Low moisture absorption

Advantages:

Cost-effective and recyclable

Excellent for living hinges and packaging

Common Applications:
Food containers, medical syringes, automotive bumpers, household goods.

3. Polyethylene (PE) – HDPE & LDPE

Properties:

Excellent toughness and flexibility

High impact resistance

Chemical and moisture resistant

Advantages:

Food-safe and widely used in packaging

Good electrical insulation properties

Common Applications:
HDPE: Bottles, crates, piping.
LDPE: Plastic bags, squeeze bottles, toys.

4. Polycarbonate (PC)

Properties:

Extremely strong and impact-resistant

Transparent with excellent light transmission

High heat resistance

Advantages:

Optical clarity similar to glass

Flame-retardant grades available

Common Applications:
Eyewear lenses, automotive headlamps, protective gear, medical devices.

5. Nylon (Polyamide, PA)

Properties:

Strong, abrasion-resistant, and durable

Excellent mechanical properties

Resistant to many chemicals

Advantages:

Suitable for demanding engineering applications

Can withstand repeated stress and wear

Common Applications:
Gears, bearings, automotive parts, sports equipment.

6. Polystyrene (PS)

Properties:

Lightweight and rigid

Good dimensional stability

Low cost

Advantages:

Easy to process

Transparent grades available

Common Applications:
Disposable cutlery, CD cases, packaging inserts, laboratory ware.

7. Polyvinyl Chloride (PVC)

Properties:

Good mechanical strength

Excellent chemical resistance

Flame retardant

Advantages:

Available in rigid and flexible forms

Cost-efficient for a wide range of uses

Common Applications:
Pipes, fittings, window profiles, electrical cable insulation.

Choosing the Right Plastic for Injection Moulding

When selecting a material, engineers and manufacturers must balance several factors:

Mechanical requirements (strength, impact, flexibility)

Environmental resistance (temperature, moisture, chemicals)

Aesthetic needs (colour, surface finish, transparency)

Regulatory compliance (food-safe, medical-grade, flame retardant)

Cost-effectiveness (raw material price and processing efficiency)

Conclusion

Injection moulding plastics form the backbone of modern manufacturing. ABS, PP, PE, PC, Nylon, PS, and PVC are the most common choices, each with strengths tailored to different industries. By understanding their properties and applications, businesses can make informed material decisions to ensure durability, performance, and cost-efficiency in their products.