Plastic mould steel materials are often used directly to make plastic molds. They are pre-hardened to a hardness level of 28-36 HRC before being made into molds. This pre-hardening helps to stop any shaping or heat treatments later on from causing cracks or deformities.
Popular plastic mold steel grades are P20 (1.2311), P20+S (1.2312), P20+Ni (1.2738), 420 (1.2083), 1.2085, NAK80, S136 etc.
P20 (1.2311)
AISI P20 Steel Plate is a versatile, low-alloy tool steel with decent strength and good toughness. It’s commonly used for making plastic injection mold cavities, tooling, and zinc die-casting dies. P20 is often found pre-hardened with a hardness near 300 HBW.
P20+S (1.2312)
P20+S is a strong alloy used for plastic mold steel, and it comes in a hardened and tempered form. Its higher sulphur content makes it easier to machine than the regular P20 plastic mold tool steel.
P20+Ni (1.2738)
P20+Ni steel is a type of plastic mold steel, similar to DIN 1.2738. It has a mix of elements like nickel, chromium, and molybdenum, which give it hardness and toughness. This particular tool steel is made specifically for the plastic mold industry, and it’s really good for large steel mold parts.
AISI 420 (1.2083)
AISI 420 steel is a type of martensitic stainless steel. It’s known for being really hardenable and strong. Plus, it’s great at resisting corrosion from both acidic and alkaline materials.
1.2085
DIN 1.2085 steel, similar to AISI 420FM, is a versatile tool steel known for its excellent resistance to both corrosion and wear. This high-quality steel, 1.2085, is commonly used for making plastic molds and dies. It’s also used in parts for the automotive and aerospace industries.
NAK80
NAK80 steel is a type of mold steel that is aged or precipitation-hardened, maintaining a steady hardness of about 40 HRC all through. It’s an exceptionally pure steel, made using Vacuum-Arc Remelting, known for its even grain structure, consistent hardness, and excellent dimensional stability.
S136
S136 is a widely used plastic mold steel, valued for its impressive toughness, ability to resist corrosion, excellent polishability, and its clean, refined steel makeup.