CNC Machining
Tool Steel
Tool steel is the cornerstone of industrial mass production. Characterized by its distinctive hardness, resistance to abrasion, and ability to hold a cutting edge at elevated temperatures, it is the ultimate material for injection molds, stamping dies, and heavy-duty cutting tools.
Core Mechanical Properties
Tool steels are defined by their response to heat treatment. Below is the typical mechanical data for common tool steels in their fully hardened and tempered state.
| Alloy Grade | Yield Strength | Tensile Strength | Hardness (Rockwell C) |
|---|---|---|---|
| D2 (High-Carbon, High-Chrome) | ~ 1650 MPa | ~ 1900 MPa | 55 - 62 HRC |
| A2 (Air-Hardening) | ~ 1400 MPa | ~ 1700 MPa | 57 - 62 HRC |
| O1 (Oil-Hardening) | ~ 1350 MPa | ~ 1650 MPa | 57 - 61 HRC |
International Grade Comparison
Matching tool steel grades globally is critical for mold making and die stamping. Use our cross-reference chart for American (AISI), European (DIN/EN), and Chinese (GB) equivalents.
| AISI / ASTM (USA) | DIN / EN (Europe) | GB (China) | Key Characteristics |
|---|---|---|---|
| D2 | 1.2379 / X153CrMoV12 | Cr12Mo1V1 | Extremely high wear resistance due to high carbon and chromium content. The absolute standard for long-run cold forming and stamping dies. |
| A2 | 1.2363 / X100CrMoV5 | Cr5Mo1V | Air-hardening steel offering a superb balance between wear resistance and toughness. Highly dimensionally stable during heat treatment. |
| O1 | 1.2510 / 100MnCrW4 | 9CrWMn | Oil-hardening steel. Very good machinability in its annealed state. Preferred for custom cutting tools, gauges, and short-run dies. |
Hardcore Industrial Applications
Tool steels are not typically used for the final product; they are the high-precision "parent tools" used to manufacture millions of other products.
Injection Mold Cores & Cavities
We 5-axis mill complex mold geometries from tool steels (like H13 or P20) capable of withstanding millions of high-pressure plastic injection cycles without losing dimensional integrity.
Stamping & Blanking Dies
D2 tool steel is CNC machined and ground to exact tolerances to create heavy-duty punches and dies that shear and form sheet metal for automotive and appliance manufacturing.
Industrial Cutting Tools & Knives
From paper shredding blades to tube-cutting shears, O1 and A2 tool steels are machined and heat-treated to retain razor-sharp edges under continuous friction.
Expert Machining Tips
Machining tool steel requires a two-phase approach: roughing in the soft state, followed by hard-milling after heat treatment. Huade engineers excel in this precise workflow:
- 1
Annealed Roughing & Allowances
We perform heavy material removal while the steel is in its annealed (soft) state. Crucially, our programmers leave specific material allowances (typically 0.2mm to 0.5mm) to account for slight warping that occurs during the quenching process.
- 2
Hard Milling (HRC 50+)
After heat treatment, the steel is incredibly hard. We utilize highly rigid 5-axis machines equipped with CBN (Cubic Boron Nitride) or TiAlN-coated solid carbide end mills to "hard mill" the part to its final, exact micron tolerance.
- 3
Integration with Wire EDM
For sharp internal corners or extreme precision in stamping dies (where end mills cannot reach), we seamlessly transition the hardened tool steel blocks to our Wire Electrical Discharge Machining (EDM) centers for flawless final cutting.
Top 3 Surface Treatments
For tool steels, "surface treatment" primarily refers to thermal processing and advanced tribological coatings designed to extend tool life.
1. Vacuum Heat Treatment
An absolute necessity. The raw part is quenched and tempered in a vacuum furnace to achieve its target Rockwell hardness (HRC) without suffering from surface oxidation or decarburization.
2. PVD Coatings (TiN, TiAlN)
Physical Vapor Deposition adds an ultra-thin, extremely hard (up to 80+ HRC equivalent) and highly lubricious layer to the tool steel. This prevents wear and galling in high-friction molding and stamping applications.
3. Black Oxide & Mechanical Polishing
To prevent rust on non-cutting surfaces, Black Oxide is applied. For injection molds, the cavities are hand-polished to an optical mirror finish to ensure plastic parts eject cleanly with a pristine surface.
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