---
title: "718H Injection Mold: Material Properties, Processing Tips, and Application Scenarios - JATERSON"
description: "Global manufacturers increasingly demand high-precision, long-lasting injection molds for complex plastic components. 718H mold steel stands out for its balanced mechanical properties, durability, and cost efficiency. Zhejiang-based manufacturing experts share actionable tips on selection, processing, and quality control to maximize mold lifespan and cut production costs."
url: "https://www.jaterson.com/manufacturing/718h-injection-mold-properties-processing-applications.html"
language: "en"
type: "Article"
category: "Injection Molding Guide"
datePublished: "2026-10-22"
dateModified: "2026-10-22"
brand: "JATERSON"
manufacturer: "JATERSON"
image: "https://static.jaterson.com/uploads/industry/injection/Kn4RCqIWaxYu7.webp"
---

# 718H Injection Mold: Material Properties, Processing Tips, and Application Scenarios

A common misconception among procurement teams and even some engineers is that 718H mold steel is simply a premium,overpriced alternative to standard P20 steel for injection molds.This couldn’t be further from the truth.718H is a pre-hardened,chromium-nickel-molybdenum alloy engineered for specific high-demand scenarios where balance between durability,precision,and cost is non-negotiable.Unlike P20,which works well for low-to-medium volume production of simple parts,718H excels in complex molds that require consistent dimensional stability over thousands of cycles,making it a strategic choice rather than a generic upgrade.

## What is 718H Mold Steel?

![JATERSON’s Guide to 718H Injection Molds: Selection, Processing, and Quality Assurance](https://static.jaterson.com/uploads/industry/injection/Kn4RCqIWaxYu7.webp)

718H is a pre-hardened mold steel,typically supplied in a 29-33 HRC hardness range,eliminating the need for post-machining heat treatment for most applications.Its alloy composition—including 0.35-0.45% carbon,1.4-1.8% chromium,1.8-2.2% nickel,and 0.2-0.3% molybdenum—delivers a unique blend of key properties:

- Excellent machinability in its pre-hardened state,reducing production lead times and machining costs
- High dimensional stability,even after repeated cycles and minor repairs
- Good weldability,allowing for easy mold modifications or repairs without compromising structural integrity
- Medium-high wear resistance,suitable for use with filled plastic resins (e.g.glass fiber,mineral filled)
- Fine-grained structure that enables mirror-like surface finishes for aesthetic or functional parts

## 718H vs.Common Mold Steels: A Comparative Analysis

To understand when 718H is the right choice,it’s important to compare it to other widely used mold steels.The following table breaks down key properties and ideal applications:

| Property | 718H | P20 | S136 | H13 |
| --- | --- | --- | --- | --- |
| Hardness (HRC post-treatment) | 29-33 (supplied) / up to 42 | 28-32 | 48-52 | 46-50 |
| Toughness | High (resists chipping in complex molds) | Medium | Medium-Low | Very High |
| [Corrosion Resistance](https://www.jaterson.com/knowledge/resistance-to-corrosion/) | Medium (resists mild moisture) | Low | High (stainless steel) | Medium |
| Machinability | Excellent (pre-hardened state) | Good | Medium (needs pre-machining before hardening) | Medium (requires post-hardening grinding) |
| Wear Resistance | Medium-High (ideal for filled plastics) | Medium | High | Very High (for abrasive materials) |
| Ideal Applications | Complex plastic components,medium-to-high volume,filled resins,precision parts | Simple parts,low-to-medium volume,non-abrasive resins | Clear/transparent parts,corrosion-prone environments | High-temperature resins,abrasive materials,high-volume production |

## Key Applications of 718H Injection Molds

718H’s balanced properties make it ideal for specific manufacturing scenarios where neither entry-level nor high-end steels offer the right mix of performance and cost.Below are the most common use cases:

- Complex structural plastic components with tight dimensional tolerances,such as automotive interior brackets,electronic enclosures,and medical device housings
- Medium-to-high volume production runs (100,000 to 500,000 cycles) where mold longevity is critical to reducing per-unit production costs
- Molds for filled plastic resins,which increase wear on mold surfaces and require a steel that can withstand abrasive forces without premature degradation
- Precision tool accessories and standard hardware parts that require consistent surface finish and dimensional stability across thousands of units
- OEM/[ODM projects](https://www.jaterson.com/custom-manufacturing/odm/) where mold modifications or repairs are likely,thanks to 718H’s excellent weldability that minimizes downtime and rework costs

## Critical Processing Considerations for 718H Molds

![Avoid 718H Injection Mold Mistakes: Critical Manufacturing and Quality Control Tips](https://static.jaterson.com/uploads/industry/default/njg9HXiRtyLMt.webp)

While 718H is relatively easy to work with,proper processing is essential to maximize its performance and lifespan.Below are key best practices from our 20+ years of manufacturing experience in Zhejiang:

### Heat Treatment Optimization

For applications requiring enhanced wear resistance,718H can be further hardened to 40-42 HRC.However,this requires strict control to avoid warping or decarburization.We recommend a two-step heat treatment process: first,pre-heat the steel to 600-650°C to release residual stress,then raise the temperature to 840-860°C before quenching in oil or air.After hardening,temper at 500-600°C to restore toughness and dimensional stability.

### Machining Best Practices

718H’s pre-hardened state allows for efficient machining,but tool selection and parameters are critical.For rough machining,use **carbide end mills with a 30-degree helix angle** to handle the alloy’s toughness without chipping.For finish machining,switch to coated carbide tools or high-speed steel (HSS) tools to achieve smooth surfaces that require minimal polishing.Maintain cutting speeds of 150-200 m/min for roughing and 250-300 m/min for finishing to prevent excessive tool wear.

### Polishing and Surface Finish

718H’s fine-grained structure enables mirror-like surface finishes (up to Ra 0.2 μm),which are essential for parts requiring high aesthetic appeal or low friction.Start with coarse abrasives (180-320 grit) to remove machining marks,then progress to finer grits (600-1200) before using diamond paste for final polishing.Avoid over-polishing,as this can degrade the mold’s surface integrity; always test a small area first to ensure the desired finish.

### Maintenance and Repair

To extend the lifespan of a 718H mold,regular maintenance is crucial.After every 10,000 cycles,inspect the mold for signs of wear,such as cavity erosion,gate damage,or surface scratches.718H’s weldability makes repairs straightforward: use a matching alloy filler rod,pre-heat the repair area to 200-250°C to avoid cracking,and stress-relieve the mold post-repair to restore [dimensional stability](https://www.jaterson.com/knowledge/dimensional-stability/).Additionally,apply a rust inhibitor after maintenance and store molds in a dry environment to prevent corrosion.

## Quality Control Checkpoints for 718H Injection Molds

Ensuring the quality of 718H molds is critical to avoiding production delays and costly rework.Below are the non-negotiable QC steps we follow at JATERSON:

- **Material Verification:** Conduct spectrometry testing to confirm the steel’s chemical composition meets 718H standards,ensuring it delivers the expected mechanical properties.
- **Hardness Testing:** Use a Rockwell hardness tester to verify the supplied steel falls within the 29-33 HRC range; post-heat treatment,check for consistent hardness across the mold surface.
- **Dimensional Inspection:** Use a coordinate measuring machine (CMM) to check cavity and core dimensions against design specs,paying close attention to tight tolerances (±0.01 mm) for precision parts.
- **Surface Finish Validation:** Use a profilometer to measure surface roughness (Ra) and ensure it meets customer requirements,especially for parts that require high gloss or smooth functionality.
- **Warpage Testing:** After machining and heat treatment,use a flatness gauge to check for warping; any deviation beyond 0.05 mm per 100 mm of mold length requires [corrective action](https://www.jaterson.com/knowledge/corrective-action/).

## Common Mistakes to Avoid with 718H Molds

Even with proper knowledge,manufacturers often make avoidable mistakes that reduce the performance of 718H molds.Here are the most frequent issues and how to prevent them:

- **Mistake 1: Skipping pre-heat treatment before machining** – This can lead to internal stress buildup and warping.Always pre-heat 718H to 150-200°C for 2-4 hours before rough machining to release residual stress.
- **Mistake 2: Using incorrect welding parameters** – Poor welding can cause cracks or soft spots.Pre-heat the repair area,use low-heat input welding,and post-weld stress-relieve to avoid these issues.
- **Mistake 3: Overlooking corrosion protection** – While 718H has medium corrosion resistance,prolonged exposure to moisture or corrosive resins can cause rust.Apply a rust inhibitor after maintenance and store molds in a dry environment.
- **Mistake 4: Running molds at excessive temperatures** – For resins requiring temperatures over 200°C,718H may not offer sufficient heat resistance.Consider switching to H13 steel or adding a heat-resistant coating to the mold surfaces.

718H injection molds are a strategic investment for manufacturers looking to balance precision,durability,and cost-effectiveness for medium-to-high volume production of complex parts.By understanding its unique properties,comparing it to alternative mold steels,and following best practices in processing and quality control,you can maximize the lifespan of your 718H molds and reduce overall production costs.As a Zhejiang-based manufacturer with decades of experience in injection molding and hardware production,our engineering team is equipped to guide you through every step of 718H mold selection,manufacturing,and maintenance to meet your specific OEM/ODM project needs.

## Related Resources

- [Injection Molding Guide](https://www.jaterson.com/manufacturing/injection-molding/)
- [Plastic Component Manufacturing Guide](https://www.jaterson.com/manufacturing/plastic-components/)
- [Hardware Manufacturing Guide](https://www.jaterson.com/manufacturing/hardware/)
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- [Custom Manufacturing](https://www.jaterson.com/custom-manufacturing/)
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- [Manufacturing Knowledge Base](https://www.jaterson.com/knowledge/)
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