Choosing mould steel is not simply about selecting the hardest material available. The correct grade must balance wear resistance, toughness, machinability, polishability, corrosion resistance and production requirements.
Different mould applications can therefore require different steels.
P20-type pre-hardened mould steels are widely used for plastic mould applications because they combine machinability, toughness and good surface-finishing properties.
H13-type tool steels offer good resistance to mechanical and thermal stresses and can be considered for demanding tooling components where higher stress and wear resistance are required.
Corrosion-resistant stainless mould steels, including 420-type grades, can be useful when tooling is exposed to corrosive polymers, humid production conditions or applications requiring high-quality polished surfaces. But steel grade alone does not determine mould life.
The correct heat treatment, machining parameters, component design, surface finish, cooling system and maintenance strategy all influence long-term performance.
At LEO Precision, material selection forms part of the complete mould-engineering process for PET preforms, caps and closures, single-stage moulds and other precision tooling.
The right mould steel is not simply a material choice—it is a production-life decision.
