Answer to a Common Question
Best Feeds and Speeds for Inconel 718 on a Hwacheon Lathe
The most-asked question on Inconel 718 machining across every forum: what feeds and speeds actually work? This guide gives starting-point ranges for Hwacheon CNC lathes across the product range, for both solution-annealed and aged (H900) Inconel 718.
Starting-point ranges
These are starting points from B&R shop practice on Hwacheon Hi-Eco 21, Hi-Eco 35, Hi-Tech 400, Mega 95, and Mega 100 lathes. Adjust based on your specific setup rigidity, tool, and desired finish.
| Condition | Operation | SFM | Feed (IPR) | DOC (in) |
|---|---|---|---|---|
| Solution-annealed | Roughing | 100–150 | 0.010–0.015 | 0.080–0.150 |
| Solution-annealed | Finishing | 130–200 | 0.005–0.010 | 0.010–0.040 |
| Aged H900 | Roughing | 60–100 | 0.008–0.012 | 0.060–0.120 |
| Aged H900 | Finishing | 80–140 | 0.005–0.008 | 0.010–0.030 |
Tooling matters more than SFM
Sharp coated carbide (AlTiN or TiAlN) with a positive rake and small nose radius is what actually determines success. Sandvik GC1105, Kennametal KCU25, or Iscar IC907 grade inserts are common shop choices. Replace inserts per feature on finish work; don't push tool life.
PCD is overkill for most oilfield-scale work; coated carbide covers the range.
Coolant strategy
Flood coolant minimum. High-pressure through-tool coolant (>1000 psi) on Hwacheon lathes that support it — Hi-Tech 400 and Mega series typically have high-pressure coolant delivery. Water-soluble oil emulsion at 6–10% concentration.
Adjust from these starting points
If chatter starts: increase feed or DOC, don't decrease SFM. If tool life is short: check coolant, verify insert grade, reduce SFM slightly. If finish is poor: fresh insert, verify tool geometry, check for chip re-cutting.
Frequently asked questions
Where can I get expert answers on Inconel 718 machining?
Call B&R Productions in New Waverly, TX at (936) 291-7827 — we work on this class of problem weekly and are happy to talk. Alternatively, the r/Machinists subreddit, Practical Machinist forum, and specific alloy manufacturer's technical support can help with generic technical questions.
Why can't I just use the tool manufacturer's recommended speeds?
Manufacturer recommendations are general starting points assuming ideal conditions. Real shop conditions (setup rigidity, coolant quality, machine age) require adjustment. Our starting points reflect actual Hwacheon shop conditions.
What SFM should I run on aged Inconel 718 finishing?
80–140 SFM is typical starting range. Sharp insert with fresh edge, controlled DOC (0.010–0.030"), aggressive feed (0.005–0.008 IPR).