Jul 10, 2026
Mold Material Cost Calculation (As Practiced in Chinese Factories)
How Chinese Factories Calculate Mold Steel Costs
Material cost typically represents 30-40% of the total mold price. Understanding how Chinese factories calculate this cost helps you evaluate quotes more effectively and negotiate with confidence.
The Calculation Formula
The standard formula used by Chinese mold shops is:
Material Cost = (Steel Weight × Price per kg) × Loss Factor
The loss factor (typically 1.5-2.5) accounts for machining waste, since a mold cavity block may start at 200kg and end at 80kg after CNC machining, EDM, and grinding.
Common Mold Steels and Their Prices (2026)
- 45# Carbon Steel — $1.5-2.5/kg. Used for prototype molds, low-volume production, and mold base plates.
- P20 (Pre-hardened) — $3-5/kg. The most popular choice for injection molds. Good machinability, pre-hardened to 30-32 HRC.
- 718H — $4-7/kg. Superior P20 with better hardness uniformity. Ideal for larger molds.
- NAK80 — $6-10/kg. Pre-hardened to 37-43 HRC with excellent polishability. Used for optical and cosmetic parts.
- S136 (420SS) — $8-12/kg. Stainless mold steel for corrosive plastics (PVC, POM with flame retardants).
- H13 (SKD61) — $5-9/kg. Hot work steel for die casting molds. Excellent thermal fatigue resistance.
- Cr12MoV (D2) — $4-7/kg. High-carbon chromium steel for stamping dies.
Material Grades by Application
Injection Molds: P20 (standard) → 718H (large molds) → NAK80 (high polish) → S136 (corrosive materials)
Die Casting Molds: H13 (standard) → DHA1 (Improved H13) → DAC55 (Premium)
Stamping Dies: Cr12MoV (standard) → SKD11 (wear-resistant) → DC53 (high-performance)
Tips to Avoid Overpaying
- Ask for the steel certificate. Reputable factories provide mill certificates showing the actual steel grade and heat treatment.
- Confirm the loss factor. A reasonable loss factor for cavity blocks is 1.5-2.0. Anything above 2.5 suggests the factory is padding costs.
- Verify actual vs. quoted material. Some factories quote P20 but use 45# steel for non-critical components. Specify that all cavity and core inserts must use the quoted steel grade.