In the procurement of high-precision injection molds, the wide quotation range for NAK80 mold steel often confuses purchasing engineers. In real purchasing cases, quotes from five suppliers ranged from approximately $6.4/kg to $9.3/kg, with a price gap of about $2.9/kg. This article is compiled from moldsteells factory’s practical experience in custom mold steel projects and is provided for reference.
For example, in a 3C product mold procurement project, the customer once chose a NAK80 grade produced in China at about $6.4/kg. During mold trials, mirror-polished areas exhibited pinhole defects, resulting in significantly higher rework costs. This case clearly shows that important technical factors lie behind the price difference.
Material Purity and Composition Control:
Core Differences in Base Cost
Material purity and composition control are the core factors that determine the base cost of NAK80. As a pre-hardened mirror-finish steel, it requires extremely high cleanliness. For example, according to ASTM E45, A-type inclusions should be ≤ 0.5 level. Insufficient cleanliness leads to internal inclusions (high-quality material has oxide content ≤ 0.002%, while lower-grade material can reach 0.01%).
The precision of key alloy elements such as nickel (8.0%–8.5%) and copper (3.0%–3.5%) directly affects performance. For high-quality material, nickel content deviation is ≤ 0.05%, whereas for ordinary grades it can reach 0.2%. The difference in composition control precision is a major contributor to the base price gap, accounting for roughly 25% of the overall difference.
Imported Material vs. Material Produced in China:
Origin and Brand as the Source of 30% Price Difference
Origin and brand are the biggest drivers behind the price gap. Imported material (such as NAK80 from Daido Steel in Japan) is typically around 30% more expensive than material produced in China. The advantages of imported brands lie in a mature process chain of “electric arc furnace + LF refining + VD vacuum degassing,” which achieves chemical composition uniformity of 99.2%.
At the same time, brands produced in China have made remarkable progress in recent years. Leading companies have improved composition uniformity to about 98.5% by introducing SMS’s continuous-casting equipment from Germany and JFE’s online analysis systems from Japan. The performance stability gap has narrowed to around 3%–5% (for example, hardness fluctuation range reduced from ±3 HRC to ±1.5 HRC).
However, import tariffs (about 6.5%) and sea freight costs (approximately $285/ton) still push the unit price of imported material higher by about $1.4–$1.7 per kg.
Heat Treatment Process and Surface Treatment:
Key Drivers of Performance Premium
The precision of the heat treatment process directly determines the performance premium. For NAK80 pre-hardening, quenching temperature must be controlled at 860 ± 5°C, with a holding time of 2.5 hours, followed by three tempering stages (200°C × 2 h + 550°C × 3 h + 600°C × 2 h). With high-quality processing, hardness uniformity can reach ±1 HRC, while ordinary materials typically fluctuate around ±3 HRC.
For surface treatment, mirror polishability is evaluated by the Ra value. Products achieving Ra ≤ 0.01 μm usually require 12 grinding steps (from 80# to 4000# sandpaper) plus electrolytic polishing. This processing adds approximately $1.1–$1.4 per kg to the cost. This performance premium accounts for about 20% of the overall price difference.
Vacuum Degassing and Minimum Order Quantity:
Invisible Cost Drivers
Vacuum degassing can increase material density to about 99.8% (compared with about 98.5% without treatment), while reducing porosity from 0.3% to below 0.05%. In one automotive interior mold project, NAK80 subjected to vacuum degassing achieved a mold life of around 500,000 shots, whereas untreated material reached only about 300,000 shots.
This process requires dedicated equipment, with a single system investment of more than $1.14 million, which increases the unit price by roughly $0.9–$1.1 per kg.
Minimum order quantity also has a significant impact. For example, a small order of 100 kg may be quoted at about $9.3/kg, while a bulk purchase of 5000 kg can bring the price down to around $7.4/kg, resulting in a gap of about $1.9/kg. This is the scale effect that reduces unit cost.
Supplier Channel:
Cost Gap Between Direct Agents and Intermediaries
Differences in supplier channels cause a terminal price gap of about $0.7–$1.1 per kg. Direct agents (such as primary agents for Daido Steel in China) can enjoy tiered original-factory pricing (annual purchases over 1000 tons receive around a 10% discount), and their inventory turnover can reach eight turns per year (versus about three turns for intermediaries), reducing operating costs by roughly 12%.
Intermediaries, on the other hand, often involve a three-level distribution chain: “mill → regional agent → distributor → end customer.” Each layer adds a margin of about 5%–8%, resulting in the final unit price being 10%–15% higher for the end user.
Conclusion
The technical factors behind the NAK80 mold steel price gap can be ranked in terms of their weight as follows:
Origin and brand (30%) > material purity (25%) > heat treatment and surface treatment (20%) > vacuum degassing (15%) > supplier channel (10%).
When purchasing NAK80, buyers should comprehensively evaluate based on mold precision, production volume, and expected mold life:
- For molds requiring high-gloss mirror surfaces (mirror finish Ra ≤ 0.02 μm), give priority to imported grades.
- If annual NAK80 consumption exceeds 50 tons, negotiate bulk pricing to leverage scale effects.
- For molds with an expected life of more than 300,000 shots, choose material that has undergone vacuum degassing.
- Request suppliers to provide chemical composition test reports, focusing on deviation values of nickel and copper.
- For small-batch procurement, give priority to leading brands produced in China, with a minimum order quantity of around 500 kg.
- Before mirror polishing, confirm the material density report, ensuring that porosity is ≤ 0.08%.
