Hardness Comparison Table of Plastic Mold Steels
The hardness of plastic mold steel is a key performance indicator, which directly affects its wear resistance, polishability, machining difficulty and service life. Different mold steels have different hardness ranges, heat treatment methods and applicable scenarios, as shown in the following comparison table.
difficulty and service life. Different mold steels have different hardness ranges, heat treatment methods and applications shown in the following comparison table.
Commonly Used Plastic Mold Steel Hardness Comparison Table
| Steel Grade | Hardness (HRC) | Heat Treatment | Application Scenarios |
|---|---|---|---|
| 45# Steel | 18-22 | Simple quenching & tempering | Prototype molds, small-batch |
| P20/718S | 28-32 | Pre-hardened (no post-treatment) | Ordinary PP/ABS parts, small-batch |
| 718H | 33-37 | Pre-hardened | Medium-surface-quality products |
| NAK80 | 35-40 | Pre-hardened | High-gloss, transparent, precision parts |
| S136/STAVAX | 50-55 | Professional quenching | High-mirror, long-life molds |
| H13/SKD61 | 48-52 | Professional quenching | Glass fiber reinforced parts, mass production |
| DC53 | 60-62 | Professional quenching | Ultra-wear-resistant molds, high glass fiber products |
Relationship Between Hardness and Mold Performance
Low Hardness Mold Steels (<30HRC)
Mainly including 45# steel and P20/718S, with low cost and easy machining, suitable for prototype molds and small-batch trial production. However, their wear resistance and rust resistance are poor, and they are prone to deformation during long-term use, which is not suitable for mass production.
Medium Hardness Mold Steels (30–40HRC)
Including 718H, NAK80 and S136H, which are the mainstream of plastic mold steels. They balance machinability, wear resistance and cost, do not require complex heat treatment, and are suitable for most medium-batch production scenarios such as home appliance panels, high-gloss parts and textured parts, with high cost-effectiveness.
High Hardness Mold Steels (>48HRC)
Mainly quenched steels such as S136, H13 and DC53, with significantly improved wear resistance, polishability and service life. However, they are difficult to machine, high in cost, and require professional heat treatment equipment, suitable for mass production, high-requirement transparent parts and glass fiber reinforced part molds.
Key Notes for Hardness Selection
Select mold steel hardness according to production scale, product material characteristics and performance requirements, balance machining difficulty and cost, and match the corresponding heat treatment method according to the steel grade to ensure mold performance.
