Injection Moulding Materials Explained: ABS, PP, Nylon, PC & More

Why does the material in injection moulding matter?

Selecting the right material is one of the most critical decisions a product designer or manufacturer makes.In injection moulding, material choice directly impacts performance, manufacturability, durability and cost.

A well-designed part can still fail if the wrong material is chosen.

Here’s why material selection matters:

• Cost per Part

  Injection moulding materials can range from ₹200 per kg to way over ₹4,000 per kg.

  Choosing a high-performance material where it’s not required can:

  • Significantly increase part cost

  • Make the final product noncompetitive in the market

  • Reduce profit margins

  Material cost must always be justified by functional or regulatory requirement.

  
  

• Strength of the Part

  A moulded part must survive real-world usage.

  • Load-bearing capacity

  • Impact resistance

  • Flexibility vs rigidity

  The geometry of the part and the material properties work together to determine whether the part will perform as intended or fail prematurely.

  
  

• Endurance & Lifetime in Field Use

  Many parts are exposed to:

  • Sunlight (UV radiation)

  • Heat or temperature cycles

  • Vibrations

  • Repeated loading and unloading

  Choosing the right grade of the right material is crucial for ensuring long-term durability and consistent performance throughout the product’s life.

  
  

• Certification & Compliance

  Material choice often determines whether a product passes or fails certification.

  Examples include:

  • Flame retardancy (UL94 ratings)

  • Electrical insulation requirements

  • Medical or food-grade compliance

  Using a material that does not meet regulatory standards can lead to costly redesigns and rejected products.

  
  

• Surface Finish, Aesthetics & Colour

  Not all injection moulding materials support every surface finish or colour equally.The final appearance of a part is a combined result of material behavior, mould finish, and colour additives.

  
  

  • Surface finish compatibility

    Some plastics polish exceptionally well (high-gloss), while others naturally produce a matte or textured look. Certain materials simply cannot replicate fine textures, no matter how good the mould finish is.

  • Colour consistency

    Different materials absorb pigments differently. This affects:

    • Colour uniformity

    • Shade accuracy

    • Batch-to-batch consistency

  
  

  • Gloss vs matte behaviour

    High-gloss finishes are easier to achieve in materials like ABS and PC, while materials such as glass-filled plastics naturally lean toward a softer, matte appearance—even with a polished tool.

  
  

  • Effect of fillers and additives

    Glass-filled or mineral-filled materials often:

    • Reduce gloss

    • Alter colour brightness

      
      

  • Colour stability over time

    Some plastics are prone to:

    • Yellowing under UV exposure

    • Fading due to heat or sunlight

    Material choice must consider long-term appearance, not just out-of-the-box aesthetics.

  
  

  • Tool finish vs material reality

    Even a perfectly polished or textured mould cannot compensate for a material that does not support the desired finish or colour effect.

  
  

•  Cycle Time & Production Efficiency

  Material properties influence:

  • Cooling time

  • Mould temperature

  • Overall cycle time

  A material with poor thermal behaviour can increase cycle time, reducing:

  • Production output

  • Cost efficiency

  Over high volumes, even 10-20 seconds per cycle make a major cost difference.

  
  

• Shrinkage in Injection Moulding

  Different plastics have different shrinkage rates during cooling.This shrinkage directly affects part dimensions, tolerances, and fit.

  A mould designed for one material may not work correctly with another, especially when tight tolerances are required. Even a small change in material can result in:

  • Dimensional mismatch

  • Warpage

  • Assembly issues

  This is why material selection must be finalised before tool design begins.

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Not All Factors Matter Equally for Every Product

While all the above considerations are important, their priority varies by application.

For example:

• Engineered plastics: Cycle time is often a lower priority compared to:

  • Dimensional accuracy

  • Mechanical strength

  • Aesthetics

• Medical components: Greater importance is placed on:

  • Absence of impurities

  • Material consistency

  • Compliance with medical standards

Understanding the end use helps determine which material properties matter most.

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Commonly Used Injection Moulding Materials & Why They Are Used

ABS (Acrylonitrile Butadiene Styrene)

• General-purpose material

• Good long-term durability

• Excellent surface finish

• Balanced strength and cost

Common uses: Consumer products, electronics housings, automotive interiors

PP (Polypropylene)

• General-purpose material

• Very cost-effective

• Lightweight and flexible

• Tends to lose shape over long periods under load

Common uses: Packaging, hinges, disposable items

HIPS (High Impact Polystyrene)

• General-purpose material

• Better shape retention than PP

• Cost-effective

• Easy to process

Common uses: Appliance housings, trays, disposable products

PMMA (Acrylic)

• Excellent scratch resistance

• High optical clarity

• Brittle compared to PC

Common uses: Light covers, display panels, transparent components

PC (Polycarbonate)

• Very high impact strength

• Excellent aesthetics and clarity

• More ductile and tougher than PMMA

• Naturally glossy finish

Common uses: Safety components, lenses, electrical enclosures

PA (Nylon – PA6 / PA66)

• High mechanical strength

• Excellent heat resistance

• Good wear and fatigue resistance

Common uses: Gears, automotive parts, industrial components

PC + ABS (Blend)

• Combines strength of PC with processability of ABS

• Good surface finish and aesthetics

• Lower cost compared to pure PC

Common uses: Automotive interiors, electronic housings

POM (Acetal / Delrin)

• Low coefficient of friction

• Excellent dimensional stability

• High stiffness

Common uses: Gears, sliding mechanisms, precision components

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Final Note

Injection moulding material selection is never “one-size-fits-all.”Each material comes with trade-offs between cost, strength, appearance, durability, and manufacturability.

The best results come from choosing a material that aligns with:

• Product function

• Manufacturing constraints

• Regulatory requirements

• Cost targets

Let us assist you with material selection.

Visit us at www.gantools.com

Other related topics :

Introduction to Injection moulding

Injection Moulding Cost in India: Tooling, Part & Hidden Costs

Low Volume Injection Moulding in India for Startups