Nickel-based superalloys (Inconel 718, 625, Waspaloy, Hastelloy) and titanium alloys are grouped as ISO S. They share one defining property: they keep their strength at cutting temperature. In steel, the chip softens as it forms and carries the heat away. In a superalloy it does not, so the heat and the mechanical load both stay at the cutting edge.
Real cutting data for ISO S
Aggregated from 1046 insert records published for heat-resistant alloys in our catalogue:
| Parameter | Full published range | Typical (median) |
|---|---|---|
| Cutting speed vc | 20 – 200 m/min | 30 – 90 m/min |
| Feed fn | 0.02 – 1.20 mm/rev | 0.10 – 0.30 mm/rev |
| Depth of cut ap | 0.15 – 10.30 mm | 0.6 – 3.2 mm |
Inconel 718 typically runs at 30–60 m/min with carbide. Titanium Ti-6Al-4V is usually 40–90 m/min. Those numbers feel slow, and they are — but raising them shortens tool life dramatically and non-linearly.
牌号s that work
Our most-stocked S-group grades: AC200M, AC100M, AP200U, AP301M, AP403M, AP351U, AP100S, AP351M, AP403S, AP010S.
These are tough, PVD-coated, fine-grain substrates. The coating must be thin so the edge stays sharp and resists chipping; a thick CVD coating will fracture under the mechanical load long before it gets a chance to wear.
The rules
1. Constant feed — never let the tool rub
Rubbing work-hardens the surface instantly and destroys the edge on the next pass. Use lead-in arcs, never dwell, and avoid spring passes. If you must dwell, retract instead.
2. Keep ap above the work-hardened layer
Same rule as stainless, more severe. Minimum ap around 0.2 mm, and vary it between passes so notch wear does not concentrate at one line.
3. Positive geometry and a sharp edge
Positive rake reduces force, heat and work-hardening. Reserve negative 刀片 for the roughest operations on rigid setups.
4. Expect notch wear
Notch wear at the depth-of-cut line is the normal failure mode in superalloys, not an anomaly. Plan insert indexing around it; the way to slow it is varying ap and using a tougher grade.
5. Use coolant — high pressure
Unlike hard turning, superalloys benefit strongly from coolant, and high-pressure coolant delivered accurately to the edge can significantly extend life. It also helps break the chips, which in Inconel are tough and stringy.
Titanium is a separate case
Titanium has low thermal conductivity and is chemically reactive with many tool materials at temperature. The rules overlap with Inconel but:
- Use a sharp, positive, uncoated or lightly coated carbide — PVD is fine, avoid anything with high titanium affinity.
- Keep speed moderate (40–90 m/min) but feed high — a thick chip carries heat away from the edge.
- Use copious coolant; titanium fires are a real risk with fine chips and insufficient cooling.
- Titanium generates thin chips that can ignite — manage chip accumulation.
Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
| Notch wear at ap line | Work-hardening (normal for S) | Vary ap; tougher grade; more coolant |
| Edge chipping | Mechanical overload / interruption | Tougher grade, honed edge, positive geometry |
| Plastic deformation | Speed too high | Lower vc substantially |
| Crater wear | Heat + chemical affinity | Lower vc, PVD grade, high-pressure coolant |
Related
- ISO 513 material groups explained
- 不锈钢 turning (ISO M)
- Carbide grades explained
- Cutting parameters calculator
Standards and further reading
The material group definitions used throughout this site follow ISO 513. The manufacturer links below are independent technical references.