Steel Selection for PET Preform Moulds: How the Right Grade Determines Mould Life
A PET preform mould is a precision instrument that operates millions of cycles over its lifetime. The steel grades used for core, cavity, and hot runner components determine whether that lifetime is 1 million shots or 5 million. Here is what every buyer needs to know.
Key Steel Grades Used in PET Preform Moulds
| Steel Grade | HRC Hardness | Corrosion Resistance | Application in Preform Mould | Typical Mould Life |
|---|---|---|---|---|
| P20 / 1.2311 | 28–34 HRC | Low | Mould plates, backing plates, lower-stress components | 500K–1M shots |
| H13 / 1.2344 | 48–54 HRC (heat treated) | Medium | Core pins, cavity inserts — standard preform moulds | 2M–3M shots |
| S136 / 1.2083 | 50–54 HRC | Excellent | Core and cavity for pharma, water, high-clarity applications | 3M–5M+ shots |
| 420 Stainless | 48–52 HRC | Excellent | Gate inserts, nozzle tips, components in wet environments | 3M–5M shots |
| Stavax ESR (S136 ESR) | 50–54 HRC | Outstanding | Mirror-finish cavity inserts; highest-quality water applications | 5M+ shots |
Shot life is indicative — actual mould life depends on maintenance, operating conditions, and cavity count
Surface Treatments and Coatings
| Treatment | Purpose | When to Specify |
|---|---|---|
| Mirror polishing (Ra < 0.05 µm) | Optical clarity; preform release | Water bottles, pharma, any high-clarity application |
| PVD coating (TiN, CrN) | Wear resistance; reduced friction | Gate inserts, ejector pins, high-wear zones |
| Hard chrome plating | Surface hardness; corrosion protection | Core pins in low-budget applications |
| Nitriding | Case hardening; improved fatigue resistance | Cavity plates, parting face surfaces |
Every Hexamech preform mould is built with certified, traceable steel. Material certificates for core, cavity, and hot runner components are part of the project documentation provided with every mould — essential for pharmaceutical customers and ISO-audited operations.
Built for Long Life — Hexamech Precision Engineering
Steel selection, heat treatment, and surface finishing at Hexamech are engineering decisions — not cost-cutting choices. Every mould component is specified for the expected production environment and shot life target.
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