Choosing the Right Tool Steel for Injection Molding

Selecting the right tool steel is one of the most critical decisions in injection mold manufacturing. The tool steel not only impacts mold durability and surface finish, but also cost, maintenance, and cycle time. With so many steel grades available, understanding the differences can save both time and money.

In this guide, we break down the most commonly used tool steels in injection molding: P20, 1.2311, 1.2738, H13, 1.2343, and others.

Why Tool Steel Matters in Mold Making

The tool steel determines:
– Lifespan of the mold (number of cycles)
– Polishability and surface finish quality
– Machinability and production speed
– Corrosion and wear resistance
– Suitability for special features like hot runners or precision inserts

Tool Steel Overview Table

Steel Grade	Region	Hardness (HRC)	Mold Life Expectancy	Key Traits
P20	USA	~28–32 (pre-hardened)	Up to 500,000 shots	Good machinability, medium wear resistance
1.2311	Europe (DIN)	~28–32 (pre-hardened)	Up to 500,000 shots	EU equivalent of P20
1.2738	Europe (DIN)	~30–36 (pre-hardened)	Up to 1,000,000 shots	Excellent polishability for large molds
H13	USA	~48–52 (after hardening)	1,000,000+ shots	High wear & heat resistance
1.2344	Europe (DIN)	~48–52 (after hardening)	1,000,000+ shots	EU equivalent of H13
1.2343	Europe (DIN)	~48–52 (after hardening)	1,000,000+ shots	Better toughness than 1.2344, great for complex molds

P20 / 1.2311

Best for: Medium-volume production molds
Delivered: Pre-hardened (~28–32 HRC)
Used for: Consumer parts, automotive trim, electronics housings
Pros: No heat treatment needed, easy to machine, low cost
Cons: Limited wear resistance, not suitable for abrasive plastics

1.2738

Best for: Large molds with high polish requirements
Delivered: Pre-hardened (~30–36 HRC)
Used for: Transparent parts, aesthetic housings, multi-cavity molds
Pros: Nickel content improves hardness uniformity and polishability
Cons: Slightly more expensive than 1.2311

H13 / 1.2344

Best for: Long-life molds with high thermal and mechanical loads
Delivered: Annealed, then hardened to ~48–52 HRC
Used for: High-temperature or abrasive plastic materials, hot runners
Pros: Excellent thermal fatigue resistance, high durability
Cons: Requires heat treatment, more difficult to machine

1.2343

Best for: Molds requiring excellent toughness and long life
Delivered: Annealed, then hardened (~48–52 HRC)
Used for: Molds with complex geometries or stress points
Pros: Better toughness than 1.2344, lower risk of cracking
Cons: Slightly less wear resistance than H13

Steel Selection Based on Mold Use

Application Type	Recommended Steel
Prototype molds	1.1730 (mild steel), P20
Medium-volume production	P20 / 1.2311 / 1.2738
High-gloss surface parts	1.2738
Transparent parts (e.g. PC)	1.2738 or hardened steels with polishing
High-temperature / abrasive plastics	H13 / 1.2343 / 1.2344
Long-life multi-cavity molds	1.2343 / 1.2344 / hardened steels

What If You’re Not Sure?

If you’re unsure which steel is best for your tool, here’s what we recommend:
– Start with P20 (1.2311) for basic needs.
– Upgrade to 1.2738 for aesthetic parts or large molds.
– Choose H13 / 1.2343 for tough jobs, long tool life, or demanding plastic types.

Our engineering team will always help you choose the most cost-effective option that meets your quality and durability expectations.

Need Help With Mold Design or Steel Choice?

Whether you’re building your first mold or scaling up production, we’re here to help. Share your part file and basic requirements, and we’ll guide you through material selection, gating systems, surface finish, and more.

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