What Is NAK80 Mold Steel?
NAK80 mold steel is a premium pre-hardened plastic mold steel designed for applications that demand exceptional surface finish, dimensional stability, and long mold life. Developed by Daido Steel, NAK80 is supplied in a pre-hardened condition and typically requires no additional heat treatment before machining.
Compared with traditional mold steels such as P20 and 718H, NAK80 offers superior mirror polishing performance, higher hardness consistency, excellent EDM machinability, and outstanding resistance to deformation during long production cycles.
Thanks to its unique nickel-copper alloy design and highly refined microstructure, NAK80 has become one of the most widely used mold steels for optical components, transparent plastic products, cosmetic packaging, automotive lighting parts, and premium consumer electronics.
For mold manufacturers seeking both high precision and excellent surface quality, NAK80 remains one of the most reliable and cost-effective solutions available today.
Quick Overview of NAK80 Mold Steel
| Property | Value |
|---|---|
| Steel Type | Pre-Hardened Plastic Mold Steel |
| Hardness | 38–42 HRC |
| Equivalent Grade | NAK80 |
| Heat Treatment Required | No |
| Surface Finish | Mirror and optical-grade polishing |
| Dimensional Stability | Excellent |
| EDM Performance | Excellent |
| Texture Etching Performance | Excellent |
| Typical Applications | Optical, transparent and high-gloss plastic molds |
Key Properties of NAK80 Mold Steel
Outstanding Mirror Polishing Performance
The most recognized advantage of NAK80 is its exceptional polishing capability.
The steel is produced with an extremely clean microstructure and very low impurity content, allowing mold makers to achieve optical-grade mirror finishes without common polishing defects such as pinholes, orange peel, or grain marks.
Proper polishing can achieve surface roughness levels suitable for:
- Optical lenses
- Transparent plastic covers
- Cosmetic packaging
- Automotive lighting components
- Premium consumer electronics
For molds where appearance directly affects product value, NAK80 is often the preferred choice.
High and Uniform Hardness
NAK80 is supplied at 38–42 HRC, providing higher hardness than most conventional pre-hardened mold steels.
Its hardness remains highly consistent throughout the steel block, helping reduce uneven wear and ensuring stable production quality over long manufacturing cycles.
Excellent Dimensional Stability
Dimensional accuracy is critical for precision molds.
NAK80 exhibits extremely low deformation during machining and production, making it suitable for:
- Thin-wall plastic parts
- Multi-cavity molds
- Precision electronic components
- Long-run production molds
The steel maintains stable dimensions even after extended injection molding operations.
Superior EDM Performance
NAK80 performs exceptionally well during electrical discharge machining.
The material produces smooth EDM surfaces with minimal recast layers, reducing polishing time and improving overall manufacturing efficiency.
Excellent Texture Etching Capability
The uniform microstructure allows NAK80 to produce highly consistent texture patterns.
This makes the material suitable for:
- Fine leather grain textures
- Matte finishes
- Decorative patterns
- Precision surface engraving
Long Service Life
The combination of high hardness, wear resistance, and structural stability helps extend mold life significantly compared with conventional mold steels.
For high-volume production environments, this translates into lower maintenance costs and reduced downtime.
Chemical Composition of NAK80 Mold Steel
The typical chemical composition of NAK80 mold steel is shown below.
| Element | Content (%) | Function |
|---|---|---|
| Carbon (C) | 0.12–0.20 | Provides balanced hardness and toughness |
| Chromium (Cr) | 1.00–1.30 | Improves wear resistance and hardenability |
| Nickel (Ni) | 3.00–4.00 | Enhances toughness and dimensional stability |
| Copper (Cu) | 0.90–1.30 | Improves hardness and polishing performance |
| Molybdenum (Mo) | 0.20–0.40 | Increases structural stability |
| Manganese (Mn) | 1.40–1.60 | Supports machinability |
| Silicon (Si) | 0.10–0.30 | Improves oxidation resistance |
| Phosphorus (P) | ≤0.010 | Controlled to reduce brittleness |
| Sulfur (S) | ≤0.005 | Maintained at extremely low levels for polishing quality |
The combination of nickel and copper is one of the key reasons NAK80 delivers outstanding polishing performance while maintaining excellent toughness and machinability.
NAK80 Mold Steel Hardness
NAK80 is supplied at a hardness range of 38–42 HRC.
This hardness level offers an excellent balance between:
- Wear resistance
- Machinability
- Surface finish quality
- Mold service life
Because the steel is already pre-hardened, mold makers can machine cavities directly without additional quenching or tempering processes.
This significantly shortens manufacturing lead times while reducing the risk of heat-treatment distortion.
Does NAK80 Require Heat Treatment?
No.
NAK80 is specifically designed as a pre-hardened mold steel and is normally supplied ready for machining.
Benefits include:
- Faster mold manufacturing
- Lower production costs
- Reduced deformation risk
- Consistent mechanical properties
- Improved dimensional accuracy
Additional heat treatment is generally unnecessary and may negatively affect the steel’s original structure and polishing performance.
NAK80 Mold Steel Equivalent Grades
NAK80 is a proprietary steel grade with no completely identical equivalent. However, several grades are often considered comparable depending on application requirements.
| Standard | Comparable Grade |
|---|---|
| Daido Steel | NAK80 |
| DIN | 1.2738 (similar application) |
| AISI | P20+Ni (similar category) |
| ASSAB | 718H (lower polishing capability) |
| Application Category | Premium Pre-Hardened Plastic Mold Steel |
Although 718H and P20+Ni may be used in similar mold applications, neither offers the same mirror polishing performance as NAK80.
Applications of NAK80 Mold Steel
Optical Plastic Molds
NAK80 is widely used for optical components requiring flawless surfaces.
Typical applications include:
- Optical lenses
- Light guide plates
- Transparent display components
- Precision optical housings
Transparent Plastic Product Molds
The steel is frequently selected for:
- Clear cosmetic packaging
- Transparent electronic covers
- Medical transparent components
- Premium consumer product packaging
Its ability to achieve mirror finishes helps eliminate surface defects that would otherwise be visible in transparent materials.
Consumer Electronics Molds
NAK80 is commonly used for:
- Smartphone components
- Tablet housings
- Wearable device cases
- Bluetooth earphone shells
The steel supports both precision dimensions and premium surface appearance.
Automotive Lighting Molds
Automotive manufacturers often choose NAK80 for:
- Headlight lenses
- Taillight covers
- Interior decorative trim
- Piano-black automotive components
The material provides both optical clarity and dimensional consistency.
High-Volume Production Molds
Because of its excellent wear resistance and stability, NAK80 is suitable for:
- Multi-cavity molds
- Automated production lines
- Long-run manufacturing projects
- High-volume consumer products
Machining Guidelines for NAK80 Mold Steel
CNC Machining
Recommended machining parameters include:
- Cutting speed: 40–70 m/min
- Feed rate: 0.08–0.20 mm/rev
- Depth of cut: 1–2 mm
High-quality coated carbide tooling is recommended for optimal results.
EDM Processing
NAK80 offers excellent EDM performance with smooth discharge surfaces and reduced polishing requirements.
Mirror Polishing
A typical polishing process includes:
320 → 800 → 1500 → 5000 grit abrasives followed by diamond paste polishing.
With proper procedures, NAK80 can achieve optical-grade mirror finishes suitable for transparent plastic products.
Texture Etching
NAK80 supports:
- Fine leather grain textures
- Matte finishes
- Decorative patterns
- Precision micro-textures
The steel delivers highly consistent etching quality across complex mold surfaces.
Welding Repair
For repair welding:
- Use compatible welding materials
- Preheat to 180–220°C
- Control cooling rates carefully
These practices help maintain surface quality and minimize distortion.
NAK80 vs 718H vs P20
Choosing the right mold steel depends on surface finish requirements, mold complexity, production volume, and budget.
| Property | P20 | 718H | NAK80 |
|---|---|---|---|
| Hardness | 28–32 HRC | 32–36 HRC | 38–42 HRC |
| Polishing Performance | Good | Very Good | Excellent |
| Mirror Finish Capability | Limited | High Gloss | Optical Grade |
| Dimensional Stability | Good | Excellent | Excellent |
| EDM Performance | Good | Good | Excellent |
| Wear Resistance | Moderate | Good | Excellent |
| Material Cost | Low | Medium | High |
Choose P20 If
- Budget is the primary concern
- Surface requirements are moderate
- Mold complexity is relatively low
Choose 718H If
- Higher precision is required
- Better polishing performance is needed
- Large mold blocks are involved
Choose NAK80 If
- Optical-grade polishing is required
- Transparent products are being manufactured
- Surface appearance is critical
- Long production runs are expected
For premium molds where surface quality directly impacts product value, NAK80 is often the best investment.
Frequently Asked Questions About NAK80 Mold Steel
What is the hardness of NAK80 mold steel?
NAK80 is typically supplied at 38–42 HRC.
Can NAK80 achieve a mirror finish?
Yes. NAK80 is specifically designed for mirror and optical-grade polishing applications.
Does NAK80 require heat treatment?
No. It is supplied pre-hardened and can generally be machined directly.
Is NAK80 better than 718H?
For mirror polishing, transparent products, and premium surface finishes, NAK80 generally outperforms 718H.
What are the main applications of NAK80?
Common applications include optical molds, transparent plastic molds, cosmetic packaging molds, automotive lighting molds, and high-end consumer electronics molds.
Conclusion
NAK80 mold steel is one of the industry’s leading pre-hardened steels for high-gloss and precision plastic mold applications. Its unique combination of mirror polishing capability, dimensional stability, wear resistance, and machinability makes it the preferred choice for optical components, transparent plastic products, cosmetic packaging, automotive lighting parts, and premium consumer electronics.
When surface quality, dimensional accuracy, and long mold life are critical, NAK80 consistently delivers outstanding performance and long-term value.
Looking for High-Quality NAK80 Mold Steel?
KUTU supplies certified NAK80 mold steel with custom cutting, rough machining, and professional technical support. Our engineering team can help you select the most suitable mold steel based on product requirements, production volume, surface finish standards, and budget.
Contact us today for a free quote and the latest NAK80 material datasheet.
NAK80 (Pre-Hardened 40 HRC) Mirror Polishing Plastic Mold Steel Plate for Precision Molds – KUTU