ABS Mold Material Selection

ABS (Acrylonitrile-Butadiene-Styrene copolymer) is a widely used engineering plastic in injection molding, valued for its impact resistance, rigidity, corrosion resistance and processability, and applied in home appliance shells, automotive interiors and electronic housings. Mold material selection directly affects mold lifespan, product precision, surface quality and costs, requiring a comprehensive choice based on ABS properties, product demands and production scenarios.

I. Core Requirements for Mold Materials

ABS has moderate melt fluidity, requiring mold temperatures of 50–80℃ during molding and no corrosive gas release, so mold materials need good wear resistance (especially for glass fiber-reinforced ABS) and polishability for high-gloss or complex products. Thermal conductivity, toughness, cost and processing cycles should also be considered according to production batches and precision needs.

II. Common Mold Materials and Applications

1. Pre-hardened Steel (Cost-Effective for Medium and Small Batches)

Pre-hardened steel (HRC 28–35) can be processed directly without heat treatment, shortening manufacturing cycles.

P20: Low-cost, suitable for small-batch (10,000–50,000 shots) products with general surface requirements.

718H: Better purity and polishability than P20, ideal for medium-batch (50,000–100,000 shots) home appliance shells.

NAK80: Precipitation-hardened steel (HRC 38–42) with mirror finish capability, applicable for high-gloss electronic housings in 100,000–300,000 shot batches.

2. Quenched and Tempered Steel (For High-Volume, High-Requirement Products)

After quenching and tempering, this steel reaches HRC 50–60, offering excellent wear resistance and dimensional stability for large batches (≥ 300,000 shots) or reinforced ABS.

H13: Good heat resistance and toughness, suitable for high-volume automotive interiors after nitriding treatment.

S136: High-purity stainless steel (HRC 58–62) with mirror polishability, ideal for high-gloss or reinforced ABS products.

SKD11: High hardness and wear resistance, applicable for simple, heavily worn parts like gears.

3. Stainless Steel (Specialized for Corrosion-Resistant Scenarios)

Used for modified ABS (flame-retardant, weather-resistant) or food-contact products to avoid corrosion or rust contamination.

SUS420J2: Heat-treatable to HRC 50–55, suitable for slightly corrosive environments.

SUS304: Excellent corrosion resistance but low hardness, requiring surface hardening for ABS mold applications.

4. Aluminum Alloy (For Rapid Prototyping and Small Batches)

Lightweight with good thermal conductivity, it shortens cooling time and cuts costs for small-batch trial production (≤ 10,000 shots). However, its low hardness and poor wear resistance limit it to simple product trials, with steel molds replacing it for mass production.

III. Key Selection Factors

Batch Size: Small batches use P20 or aluminum alloy; medium batches choose 718H/NAK80; large batches or reinforced ABS adopt H13/S136.

Surface Quality & Precision: General surfaces use P20/718H; mirror finishes require NAK80/S136; precision parts prioritize dimensionally stable steels.

ABS Type & Process: Reinforced ABS needs high-hardness steel; flame-retardant/weather-resistant ABS may require stainless steel; high-temperature processes favor heat-resistant materials like H13.

Cost & Cycle Balance: Avoid overusing high-end materials for low-requirement products; use composite structures (high-end steel for cores, ordinary steel for bases) to save costs. Pre-hardened steel shortens processing cycles, while quenched and tempered steel takes longer.

IV. Practical Cases

Ordinary home appliance shells (100,000 shots): 718H balances cost and lifespan.

High-end electronic housings (300,000 shots): S136 ensures mirror finish and wear resistance.

Reinforced ABS automotive parts (500,000 shots): H13 with nitriding treatment resists severe wear.

Small-batch toy trials (5,000 shots): Aluminum alloy enables rapid, low-cost validation.

V. Conclusion

ABS mold material selection should balance performance, cost and efficiency. 718H and NAK80 are cost-effective for ordinary scenarios; H13 and S136 suit high-volume, high-requirement products; aluminum alloy works for trials. Heat treatment and surface processing should be considered alongside material selection to ensure stable mold performance.