ABS Injection Moulding: Properties, Uses & Design Guide
ABS (Acrylonitrile Butadiene Styrene) is the most widely used engineering thermoplastic in injection moulding. It combines rigid structural stiffness with good impact resistance, processes easily across a broad temperature window, and accepts a wide range of surface finishes. For product housings, enclosures, and structural consumer goods, ABS is typically the first material to evaluate.
What are the mechanical and thermal properties of ABS?
ABS is a two-phase polymer: a rigid SAN (styrene-acrylonitrile) matrix reinforced by dispersed butadiene rubber particles. The rubber phase absorbs impact energy; the SAN matrix provides stiffness and surface quality. This balance gives ABS predictable, all-round performance that neither PP nor PS can match at the same price point.
| Property | Typical Value | Test Standard |
|---|---|---|
| Tensile Strength | 40–50 MPa | ISO 527 |
| Flexural Modulus | 2,100–2,800 MPa | ISO 178 |
| Izod Impact (notched) | 200–400 J/m | ISO 180 |
| Rockwell Hardness | R100–115 | ASTM D785 |
| Heat Deflection Temp (0.45 MPa) | 88–100°C | ISO 75 |
| Vicat Softening Point | 95–110°C | ISO 306 |
| Density | 1.02–1.06 g/cm³ | ISO 1183 |
| Mould Shrinkage | 0.4–0.7% | ISO 294-4 |
| Water Absorption (24 h) | 0.2–0.4% | ISO 62 |
Heat deflection temperature varies significantly by grade — high-heat ABS grades can reach 110°C HDT by blending with maleic anhydride copolymers.
Where is ABS injection moulding used?
ABS is the default material for a broad range of product categories. Its processability, finishing options, and cost-effectiveness make it the go-to choice when no extreme requirement (temperature, chemical exposure, optical clarity) rules it out.
Consumer electronics: Laptop casings, keyboard keycaps, remote control shells, and printer bodies. ABS provides the dimensional accuracy needed for snap-fit assemblies and the surface quality needed for painted or textured aesthetics.
Automotive interior trim: Dashboard panels, pillar covers, door pockets, and bezel components. Automotive grades often include flame retardants or UV stabilisers.
Medical device housings: Diagnostic equipment enclosures, monitor bezels, and trolley shells. Medical-grade ABS grades meet ISO 10993 biocompatibility requirements.
Power tool bodies and industrial enclosures: ABS balances rigidity and impact resistance well for hand-held tools. UL 94 V-0 flame-retardant grades are available for electrical enclosures.
Toys and consumer goods: LEGO bricks are famously ABS, exploiting the material's tight dimensional tolerances and paint adhesion.
What are the moulding characteristics of ABS?
ABS is a forgiving material to process. Its wide processing window and low sensitivity to moisture (relative to nylon or PC) reduce cycle-time sensitivity and startup scrap.
Melt temperature: 220–270°C depending on grade. Higher-flow grades process at the lower end; high-heat grades require the upper end.
Mould temperature: 40–80°C. Higher mould temperatures improve surface gloss and reduce internal stress; lower temperatures speed cycle time. For high-gloss parts, 60–80°C is recommended.
Injection pressure: 50–150 MPa. ABS is shear-sensitive at high injection rates; gradual fill profiles reduce jetting and weld-line weakness.
Drying: ABS must be dried before processing. Inadequate drying causes surface splay, silver streaks, and reduced impact strength. Standard drying: 2–4 hours at 80°C in a dehumidifying dryer.
Shrinkage: 0.4–0.7%. Flow direction shrinkage is slightly lower than transverse shrinkage, which must be accounted for in asymmetric parts.
Draft angles: Minimum 1° on unpainted surfaces; 2–3° on textured surfaces to avoid drag marks during ejection.
Sink and warp: ABS has lower shrinkage than PP and warps less. Sink marks appear at walls thicker than 4 mm or at rib-to-wall junctions where the nominal ratio exceeds 60%.
Which ABS grades and variants should you consider?
Not all ABS is the same. Grade selection should be driven by the application's dominant requirement.
| Grade / Variant | Key Modification | Typical Use |
|---|---|---|
| Standard ABS | Baseline | General housings, enclosures |
| High-impact ABS | Higher rubber content | Handles, brackets |
| High-heat ABS | SAN copolymer blend | Automotive, appliances |
| Flame-retardant ABS (V-0) | Halogenated or halogen-free FR | Electrical enclosures |
| UV-stabilised ABS | Hindered amine + UV absorbers | Outdoor / signage |
| Medical-grade ABS | Low extractables, ISO 10993 | Medical device shells |
| ABS + PC blend | PC matrix | High-impact, elevated temp |
| ABS + GF (10–30%) | Glass fibre | Structural, dimensional stability |
Glass-filled ABS offers a substantial increase in stiffness (flexural modulus up to 6,000 MPa at 30% GF) at the cost of surface finish quality. If aesthetics matter, a standard grade is preferable.
What are ABS's advantages and limitations?
Advantages:
- Excellent all-round balance of stiffness, impact resistance, and processability
- Low shrinkage and good dimensional stability
- Accepts painting, electroplating, chrome, and UV-curing lacquers
- Wide choice of grades for heat, flame, and UV requirements
- Lower tooling cost than PC-only parts due to lower processing pressures and temperatures
Limitations:
- Moderate chemical resistance — solvents (acetone, MEK, esters) attack it aggressively
- Poor UV stability in standard grades; yellows outdoors within months
- Not suitable for continuous service above 90°C in standard grades
- Lower stiffness than PC or POM for precision mechanical parts
- Not intrinsically food-safe; specific compliance grades required
When should you choose ABS over alternative materials?
ABS vs PP: Choose ABS when you need tighter tolerances, better surface quality, or snap-fit stiffness. PP is preferred when chemical resistance, living hinges, or low cost per kilogram matters more.
ABS vs PC: Choose ABS when you don't need optical transparency or continuous service above 90°C. PC costs more per kilogram and is harder to process; ABS is the economical default for opaque housings.
ABS vs POM: Choose ABS for housings and aesthetic parts. Choose POM when you need precision sliding contact, high fatigue life, or low friction.
ABS vs ASA: For outdoor parts exposed to UV and weathering, ASA (Acrylonitrile Styrene Acrylate) is a direct weatherable substitute with similar processing and almost identical mechanical properties.
Is ABS recyclable?
ABS is technically recyclable (resin code 7 — Other) but is not widely collected in municipal streams. Mechanically recycled ABS is commercially available and used in automotive and electronics sectors, typically blended with virgin resin to maintain impact performance. Recycled content reduces tensile strength slightly; Nordmould can discuss recycled-content grades where applicable.
Flame-retardant ABS grades containing halogenated additives have more restricted recycling pathways. Halogen-free FR grades are preferable where end-of-life recyclability is a product requirement.
Frequently asked questions
What is the shrinkage rate of ABS in injection moulding?
ABS typically shrinks 0.4–0.7% during injection moulding. This is lower than PP and more predictable than PC, making it a reliable choice for dimensionally critical housings. Nordmould accounts for exact shrinkage in the tool design based on the specific grade selected.
What wall thickness should I use for ABS injection moulding?
For ABS, a wall thickness of 1.5–3.5 mm is recommended. Walls thinner than 1.2 mm risk incomplete fill; walls thicker than 4 mm increase the risk of sink marks and voids. Nordmould reviews wall thickness during the free DFM process.
Can ABS be used for outdoor parts?
Standard ABS has limited UV resistance and can yellow or become brittle with prolonged outdoor exposure. For outdoor applications, UV-stabilised ABS grades or a switch to ASA (a weatherable cousin of ABS) is advisable. Nordmould can source UV-stabilised grades on request.
What surface finishes are possible with ABS?
ABS accepts matt, glossy, and textured finishes very well. It paints, chrome-plates, and electroplates readily, making it a preferred material for consumer products requiring decorative surfaces. High-gloss finishes are achievable but require polished steel tooling.
Is ABS food-safe for injection moulding?
Standard ABS is not certified food-safe. Food-contact applications require specific FDA- or EU-regulation-compliant grades. If your application demands food-contact compliance, discuss material selection with Nordmould during the DFM review stage.
How does ABS compare to PC/ABS blends?
PC/ABS blends offer higher impact strength and heat resistance than pure ABS, at a higher material cost. Pure ABS is sufficient for most general-purpose housings and is easier to process. Nordmould offers guidance on whether a blend is warranted for your specific application.
What is the minimum order quantity for ABS parts at Nordmould?
Nordmould's minimum order quantity is 100 pieces, applicable to all standard materials including ABS. Tooling starts from €3,000, with aluminium bridge tooling available for low-to-mid volume runs.
Send your STEP file to Nordmould for a free DFM review and written quote — typically returned within one business day.