2-Flute · nACo · R4mm Ball · HRC65 · Standard Reach
8mm 2-Flute nACo Solid Carbide Ball Nose End Millfor HRC65 Hardened Steel 3D Contouring
nACo (nano-AlCrN composite) ball nose end mills represent the pinnacle of carbide ball-end tooling for hard milling. With coating hardness exceeding 3,800 HV and oxidation stability up to 1,100°C, nACo enables dry Z-level finishing in hardened mould steel (P20, H13, S7, D2) up to HRC65 — directly replacing the need for grinding after heat treatment. 2-flute geometry reduces vibration in long-reach configurations common in deep die cavities. Achieves Ra 0.4–0.8µm surface finish in HRC65 steel.
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Reference price
$34.28
Ref. factory price (USD)
Based on rod stock cost as of 2026-03-31. Final quotation may differ.
R4mm 2F nACo Ball Nose EM
L2 20mm · D2 8mm · OAL 60mm
Standard Reach · HRC65
✓ Factory direct pricing
✓ MOQ 1 piece, ships 1–5 days
✓ Custom ball radii available
Full Dimensions
Technical Specifications
| Ball Radius (R) | 4 mm |
| Cutter Diameter (D1 h7) | 8 mm |
| Flute Length (L2) | 20 mm |
| Shank Diameter (D2 h6) | 8 mm |
| Overall Length (L1) | 60 mm |
| Number of Flutes | 2 |
| End Geometry | Ball Nose (Spherical) |
| Coating | nACo Nano-AlCrN composite |
| Max Material Hardness | HRC65 |
| Reach Category | Standard (L1/D1 = 7.5×) |
| Substrate | K10/K20 Ultra-Fine Grain Carbide |
| Shank Tolerance | h6 |
| MOQ | 1 piece |
| Lead Time (standard) | 1–5 business days |
| Lead Time (custom) | 5–15 business days |
nACo · 2 Flute · HRC65
Where This Tool Excels
R4mm nACo 2F — Recommended Applications
- ▸Large mould cavity semi-finish and finish passes
- ▸Automotive stamping die contouring
- ▸Compound curve aerospace structural parts
- ▸Forging die cavity profiling
3D Finishing Reference
Scallop Height vs Step-Over — R4mm
Residual scallop height (cusps) between adjacent tool paths, calculated for R4mm ball nose:
| Step-Over | Step-Over mm | Scallop Height (µm) | Typical Ra (µm) |
|---|---|---|---|
| 2% D1 | 0.16 | 0.8 | ≈ 0.16 |
| 5% D1 | 0.40 | 5.0 | ≈ 1.00 |
| 8% D1 | 0.64 | 12.8 | ≈ 2.56 |
| 10% D1 | 0.80 | 20.1 | ≈ 4.01 |
| 15% D1 | 1.20 | 45.3 | ≈ 9.05 |
| 20% D1 | 1.60 | 80.8 | ≈ 16.16 |
h = R − √(R² − (ae/2)²). Actual Ra depends on feed rate, chip load, and material.
Coating Performance
nACo — Why It Works for Ball-End Machining
- ▸nACo hardness > 3,800 HV — sustains edge sharpness in HRC65 steel
- ▸Oxidation stable to 1,100°C — enables dry hard milling
- ▸Eliminates grinding after heat treatment for mould steel
- ▸Achieves Ra 0.4–0.8µm in HRC65 P20/H13/S7/D2 steel
- ▸2-flute reduces vibration in deep-cavity long-reach cuts
Related Ball Nose Variants
Same Size in Other Coatings
Same Ball Radius, Different Reach
R4mm nACo · 2 Flute · HRC65 — Other Flute Lengths
Order R4mm 2-Flute nACo Ball Nose Today
Factory direct. MOQ 1 piece. Pricing confirmed within 4 hours.