What kind of steel is used for ABS plastic molds?
2026-01-05 15:26:52
Injection Molds
ABS materials, with balanced strength, toughness and processability, are widely used in home appliances, automotive and electronics industries. The steel selection for ABS injection molds directly determines product dimensional accuracy, surface quality and production efficiency. Rational selection should be based on ABS properties, product requirements and production volume, aligned with current mold steel trends to balance performance and cost.
I. Requirements of ABS Properties for Mold Steel
1. Process Compatibility Requirements
ABS has a wide melting range. During injection molding, molds bear moderate temperature (25–70°C) and pressure (500–1000 bar). Thus, steel must have stable heat and pressure resistance to avoid deformation under long-term cyclic conditions.
2. Molding Quality Requirements
ABS has moderate fluidity and stable shrinkage, enabling high-precision appearance parts production. It requires mold cavities with excellent polishability and low surface roughness. For flame-retardant modified ABS, trace corrosive gases may be released, demanding certain corrosion resistance of steel.
II. Common Steel Types & Applications for ABS Injection Molds
1. Pre-Hardened Steel: Cost-Effective
Pre-hardened steel (e.g., P20, 718H) is ready for machining without secondary heat treatment, shortening mold cycle. P20 is suitable for small-to-medium batch general ABS products (100,000–300,000 shots). 718H, an improved version, fits high-precision ABS or glass fiber-modified ABS (300,000–500,000 shots).
2. Mirror Steel: For High-Gloss Parts
NAK80 is preferred for high-gloss ABS parts (e.g., appliance panels). It achieves high hardness in pre-hardened state, with over 10,000-mesh polishing grade and 500,000–1,000,000 shots life, ensuring mirror finish without heat treatment.
3. Corrosion-Resistant Steel: For Special Modified ABS
S136, with high chromium content, offers excellent corrosion resistance and polishability, suitable for flame-retardant or acid-alkali resistant ABS (e.g., medical, food packaging) with over 500,000 shots life. Chrome-plated ordinary pre-hardened steel is an alternative for cost control.
4. Hot Work Steel: For Extreme Conditions
H13 steel is used for glass fiber-reinforced ABS, resisting severe scouring and wear with excellent heat resistance and high hardness after heat treatment, suitable for mass production of high-strength ABS.
III. Core Principles for Steel Selection
1. Match Production Volume
Choose P20 for small-batch general products, 718H/NAK80 for large-batch high-precision products, and H13 for ultra-large-scale glass fiber-reinforced ABS production.
2. Align with Product Quality
P20 for ordinary structural parts, NAK80 for high-gloss/transparent parts, and S136 for corrosive modified ABS.
3. Balance Cost & Performance
Avoid over-selecting high-end steel. For example, 718H with fine polishing meets general ABS appearance requirements instead of costly NAK80.
IV. Steel Selection Trends
With mold steel industry moving towards high-end, intelligent and green development, new powder metallurgy steel is increasingly used in high-precision ABS molds. Digital technology enables data-driven selection, while green technologies (e.g., chromium-free passivation) replace traditional chrome plating.
In summary, steel selection for ABS injection molds should integrate ABS properties, production volume, product requirements and cost, with attention to technological trends to ensure stable efficiency and quality.
