Buyer Guide
How to Choose Mold Steel: P20, 718H, H13, S136 and 420
Mold steel should match resin, texture, polish, corrosion, expected shots and maintenance plan.
Why this matters
Mold steel should match resin, texture, polish, corrosion, expected shots and maintenance plan. Steel choice should follow resin, expected shots, polish, texture, corrosion risk and maintenance plan rather than a single default grade.
Buyer checks
Match steel to mold life and resin abrasivenessConfirm polish or optical requirementsReview corrosion risk from resin, additives or cooling environmentAsk which inserts or wear areas need higher-grade steelDocument maintenance and repair assumptions
Quote variables
| Quote variable | Why it changes the mold route |
|---|---|
| Resin | Glass fiber, flame retardants and corrosive materials change steel choice. |
| Polish | Clear or glossy parts may need steel that polishes and holds surface quality. |
| Shot life | Longer life can justify harder or higher-grade steel. |
| Maintenance | Wear areas may need inserts or localized steel upgrades. |
Common mistakes
Choosing the cheapest steel without mold-life contextUsing one steel grade for every insert and wear surfaceIgnoring resin corrosion or polish needs
How to apply it
Ask the supplier to explain the steel selection against resin, surface finish, volume and warranty expectations. If the project is early, the guide can show whether the next move is CAD cleanup, DFM review, prototype tooling, production mold planning, export mold handoff or repair review.