Machining Speeds and Feeds Calculator: Spindle Speed, Feed Rate, Metal Removal Rate and Cutting Time

Set the spindle speed and the feed rate for a cutter or for turning.

Calculated from standard textbook formulas, with every step shown. The formulas are fixed, so the working does not need checking: what matters is the numbers you type in. Use these calculators only if you are competent to choose the inputs (loads, material strength, dimensions, supports) and check your units and assumptions. For learning and checking your own working: design and sign-off are for a qualified engineer. Drafting Central does not store the numbers you type.

How this calculator works

Choose milling (or drilling) or turning, and enter the cutting speed, the diameter, and for milling the number of flutes. Enter the feed for each tooth or revolution, the depth and width of cut and the length to cut.

The calculator finds the spindle speed N = 1000 Vc over pi D and the feed rate, then the metal removal rate and the cutting time.

It gives typical carbide cutting speeds for common materials as a starting point.

Formulas used

  • N = \frac{1000\,V_c}{\pi D}
  • v_f = f_z\,z\,N
  • \mathrm{MRR} = \frac{a_p a_e v_f}{1000}\ \ (\text{milling})
  • \mathrm{MRR} = V_c f a_p\ \ (\text{turning})

Worked example

With the default numbers in the calculator above:

  1. Spindle speed: 4774.65 rev/min
  2. Table feed rate: 954.93 mm/min
  3. Metal removal rate: 9.55 cm3/min
  4. Feed for each revolution: 0.20 mm per revolution
  5. Cutting time for the length you gave: 0.21 min (12.57 s)

Change the numbers in the calculator to see the full working, every step, for your own case.

Common questions

What is the cutting speed?

The speed of the cutting edge over the work in metres a minute. It is set by the tool material and the work material.

What is chip load?

The thickness of material removed by each tooth, which is the feed for each tooth. Too small and the tool rubs, too large and it breaks.

Why does a bigger cutter turn slower?

The edge of a big cutter travels farther in each turn, so it reaches the same cutting speed at fewer revolutions.

Are these figures safe to use?

They are starting figures. Reduce them for a weak machine or a long tool, and follow the tool maker's data.

Related calculators

Got a question about this? Ask an engineering question and get a plain-language answer with references.

Further reading: Machinery's Handbook (cutting speeds and feeds); Sandvik Coromant and Kennametal cutting data guides.

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