Advantages of cBN tools in hardened steel machining
Proper cutting work
requires a tool that is three times harder than the work material!
Characteristics of cBN end mill
Concept of cBN end mill
Innovation from electrical discharge machining to direct milling
- Reduced delivery time Example: Previously, 5 days for mold designing + 5 days for electrode processing + 5 days for electrical discharging/finishing, or 15 days in total. Presently, 5 days for mold designing + 1 day for direct milling, or 6 days in total.
- Reduced cost (75% reduction in power consumption, and no need for electrode fabrication) → Resource savings
- No drain from electrical discharge machining (0 → Eco-friendly)
Cuts two times faster and lasts five times longer than carbide-coated tools.
- Reduced machining time
- Fewer changes of tools during long period of cutting
- Less time for polishing process
Direct milling vs. electrical discharge machining
| Workpiece | Bevel gear cavity (60×60×50) |
| Work material | DC53 (HRC60) |
| Processing machine | Yasuda Precision Tools YBM640V |
| Cutting fluid | Oil mist (cBN for dry machining) |
| Tools used | Five carbide end mills, eight R1s, one cBN end mill |
| Machining description | Machining test by direct milling with carbide tools and cBN tool. (Time and surface roughness compared with conventional electrical discharge machining) |
| Cutting conditions | ||||
| Machining process | Tool used | Rotational frequency (min−1) | Feed(mm/min) | Machining time(min) |
| Prepared hole machining | Carbide R5 ball end mill | 600 | 240 | 7.4 |
| Roughing | Carbide φ10 end mill | 4,000 | 2,500 | 6.2 |
| Semi-roughing | Carbide R3 ball end mill | 5,000 | 1,200 | 19.0 |
| Semi-finishing | Carbide R1.0 ball end mill | 8,500 | 2,000 | 36.1 |
| Semi-finishing | Carbide R1.0 ball end mill | 15,000 | 2,400 | 28.5 |
| Final finishing | cBN R1.0 ball end mill | 20,000 | 2,000 | 50.3 |
| Prepared hole machining | Carbide R5 ball end mill | 600 | 240 | 7.4 |
| Roughing | Carbide φ10 end mill | 4,000 | 2,500 | 6.2 |
| Semi-roughing | Carbide R3 ball end mill | 5,000 | 1,200 | 19.0 |
| Semi-finishing | Carbide R1.5 ball end mill | 8,500 | 2,000 | 36.1 |
| Semi-finishing | Carbide R1.0 ball end mill | 15,000 | 2,400 | 28.5 |
| Final finishing | cBN R1.0 ball end mill | 20,000 | 2,000 | 50.3 |
Conclusion:
Approx. 10 h with conventional method (electrical discharge machining + polishing) vs. approx. 2.5 h with direct milling method
This translates to a 75% reduction in time.
Features of our CBN tool: Electrolytic abrasive grain polishing
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| Unprocessed product (Grinding stone traces are seen, with the likelihood of causing surface accuracy deterioration and chipping.) | Processed product (The smooth cutting edge provides high accuracy and long life.) |
