Mold Materials

Selecting the right mold steel is critical for tool life, part quality, and cost efficiency. Different applications require different material properties: hardness, wear resistance, corrosion resistance, polishability, thermal conductivity, and machinability.

Pre-Hardened Steels (28-38 HRC)

P20 (AISI 618) is the most economical general-purpose steel for low to medium volume molds. 1.2311 and 1.2312 offer improved machinability with sulfur addition. P20+Ni provides better through-hardening for larger molds. Typical applications: household appliance parts, automotive interior trim, toys, and general industrial parts.

Through-Hardening Steels (48-52 HRC)

H13 (AISI H13, 1.2344) offers excellent toughness and resistance to thermal fatigue, making it ideal for die casting and high-temperature molding. 1.2343 ESR has finer carbide distribution for better polishability. Suitable for high-wear applications: connectors, gears, and molds with tight tolerances.

Corrosion-Resistant Steels

S136 (AISI 420, 1.2083) provides good corrosion resistance for PVC, POM, and other corrosive materials. S136H is the pre-hardened version at 30-35 HRC. 1.2316 offers improved corrosion resistance over 1.2083. Stainless mold steels require careful heat treatment to avoid decarburization.

High-Polish Steels (Mirror Finish)

NAK80 (40 HRC pre-hardened) provides excellent polishability to mirror finish (SPI A1) without heat treatment. STAVAX ESR (AISI 420 modified) achieves superior corrosion resistance and polishability. Typical applications: optical lenses, transparent parts, and medical devices requiring mirror surfaces.

Surface Treatments

Nitriding (gas or plasma) increases surface hardness to 900-1100 HV. PVD coating (TiN, TiCN, TiAlN, CrN) provides wear and corrosion resistance. Hard chrome plating (20-50 microns) improves surface hardness and release properties for rubber molds. Texturing (chemical etching) creates specific surface finishes for cosmetic parts.