Injection Mold Steel Grades: Complete Comparison Chart

Selecting the right steel grade for your injection mold is one of the most important decisions in tooling. This guide provides a complete comparison of common mold steel grades, their properties, and recommended applications.

Mold Steel Grade Families in Our Tooling Program

Taize builds injection molds from pre-hardened, hot-work and corrosion-resistant steel families, supplied by certified international mills. The grade for a project is selected on part material, surface requirement and run volume after free DFM analysis — the table below shows the families, their supply sources and the applications Taize routinely builds them for.

Grade family	Supply source	Typical Taize applications
P20 / P20HH	ASSAB (IMPAX PX88), Finkl (P20HH)	General-purpose injection molds, prototype and low-volume tools
718 (718S / 718HH)	ASSAB (IMPAX)	Automotive panels, appliance housings, high-gloss surfaces
H13 (ORVAR8407 / 1.2344 / GS2344)	ASSAB, Böhler, Buderus, Saarstahl	Hot-work, die-casting molds, engineering-plastic tooling
NAK80 / NAK55	Daido (Japan)	Optical, transparent and mirror-finish cavities
S136 / STAVAX	ASSAB (STAVAX)	Food-contact, medical, corrosion-resistance
Cold-work (DC11 / DC53)	Daido (Japan)	Stamping-die inserts and wear components

P20 Steel

P20 is the most commonly used pre-hardened mold steel for general-purpose injection molding. It is supplied pre-hardened (P20HH / IMPAX PX88 in our steel program), so cavities can be machined without a separate post-machining heat-treatment step, shortening tooling lead time. It is the economical first choice for commodity plastic parts where the surface requirement is moderate.

718H Steel

718H offers higher hardness than P20 with superior polishability. It is a standard Taize selection for automotive interior and exterior panels, appliance housings and parts demanding a high-gloss surface, and it resists the fine wear caused by glass-filled compounds better than P20. It carries a modest price premium over P20.

H13 Steel

H13 is the hot-work tool steel used for high-temperature applications. It retains strength at elevated temperature and resists heat checking, making it suitable for die-casting molds and for injection tooling running engineering plastics such as nylon (PA), PC and PEEK. In our program it is supplied as ORVAR8407 (ASSAB), 1.2344 (Böhler/Buderus) or GS2344 (Saarstahl).

NAK80 and S136 for Specialty Surfaces

For mirror-finish and optical cavities, Taize uses NAK80 (Daido) which machines to a high polish in the pre-hardened state. For food-contact, medical and corrosive-resin applications we specify S136 / STAVAX stainless mold steel, which combines hardness with corrosion resistance and is straightforward to clean and maintain.

How to Choose the Right Grade

For most projects, Taize starts from P20 for general use, moves to 718H when a higher-gloss surface or longer life is required, and selects H13 or S136 for engineering plastics, medical or high-temperature applications. The final grade is confirmed against DFM and verified in the mold trial before production release.

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