Turning cycle time calculator
Minutes per part for a turned job, with every pass shown so you can argue with it. RPM comes from surface speed, passes come from stock on the radius, minutes come from feed per revolution. No fudge factors.
The part
Inches and minutes. Change anything that does not match your machine.
Conservative carbide numbers. A rigid setup can push them.
On the radius
0 if solid
0 to skip parting
Air moves, tool changes, gauging
The line most estimates leave out
Handling time — air moves, tool changes, opening the door, measuring, deburring — is not cutting, so it tends to fall out of the calculation. On a part with a ninety second cut, two minutes of handling means the estimate is less than half of reality.
It is a separate line here on purpose. If your number looks wrong, that is usually the one to change first, and the honest way to find your real figure is to time yourself on a few parts rather than guess.
Common questions
- How do you calculate cycle time for a turned part?
- Work out RPM from surface speed and diameter — RPM = (SFM × 12) ÷ (π × diameter in inches). Then each pass takes length ÷ (feed per revolution × RPM) minutes. Count roughing passes by dividing the stock on the radius by your depth of cut. Add facing, drilling, parting and, critically, handling time.
- What surface speed should I use?
- With carbide, roughly 450 SFM on mild steel, 350 on 4140, 250 on 304 stainless and 1000 on aluminum. Those are conservative mid-range numbers for a shop with decent rigidity. A tight setup on a modern machine can go considerably faster; a worn manual lathe cannot.
- Why is my real cycle time longer than the calculation?
- Almost always because the calculation left out the parts that are not cutting: tool changes, air moves, opening the door, measuring, deburring and the first article you scrap. On short-cycle parts this handling time can be more than the cutting. That is why it is a separate, editable line here rather than hidden in a fudge factor.
- Does cycle time include setup?
- No. Cycle time is per part. Setup is once per lot, and mixing them is the most common quoting mistake in a job shop — it makes small lots look profitable and large lots look expensive.
Cycle time is half the quote
The other half is what an hour costs you and how the setup gets spread. Both are a click away.