Usage Specifications for P20 Injection Mold Steel
P20 steel (GB 3Cr2Mo, WNr 2311) is the most widely used pre-hardened plastic mold steel. It offers good machinability, polishing performance, and toughness with factory hardness HRC 30–36. It is widely applied in medium-precision, medium-volume molds for household appliances, automotive interiors, daily necessities, and general plastic parts. Proper selection, processing, heat treatment, welding, and maintenance directly determine mold life and product quality. This article provides complete and practical usage specifications.
P20 is suitable for molding ABS, PP, PS, PE, and general modified plastics. It is cost-effective for molds requiring 100,000 to 500,000 shots. However, it is not recommended for corrosive materials such as PVC or POM, which may cause rust and corrosion. For such materials, surface chrome plating or corrosion-resistant steels are better choices. P20 is also not ideal for ultra-high-wear scenarios, where through-hardened steels are more suitable. Correct material selection avoids premature failure and reduces maintenance costs.
Machining Process RequirementsP20 requires stress relief before machining to prevent deformation. Rough machining should be followed by tempering to eliminate internal stress. Finishing allowance is generally 0.1–0.3mm. Polishing follows a step-by-step coarse to fine sequence to avoid surface softening. High-gloss surfaces can be achieved with chemical or electrolytic polishing. Cutting tools and parameters must be matched to tool performance to ensure dimensional accuracy and surface quality. Stable processing reduces deformation and improves consistency.
