Milling speed and feed
How cutting speed, tool diameter, teeth and feed per tooth create initial machine settings for milling.
ENGINEERING PRINCIPLE
Cutting speed sets spindle speed at a selected tool diameter; feed per tooth multiplied by teeth and rpm gives table feed.
N = 1000Vc/(πD); Vf = fz z NVariables and units
- Vc = cutting speed (m/min)
- D = tool diameter (mm)
- fz = feed per tooth (mm/tooth)
- z = tooth count
Worked example
For Vc = 120 m/min, D = 16 mm, fz = 0.08 mm/tooth and z = 4, N ≈ 2,387 rpm and Vf ≈ 764 mm/min.
Calculation method
- Select a starting cutting speed for the tool and work material.
- Calculate spindle rpm from tool diameter.
- Apply feed per tooth and tooth count, then verify machine and tool limits.
Practical applications
- Milling setup sheets
- CNC program preparation
- Machining process comparison
Review boundary and reference
- Rigidity, radial engagement, tool coating, coolant and power can require lower values.
- Use validated shop data and tooling guidance for production release.
Formula and displayed units independently checked for the stated conditions. This is not a code-compliance design method.
Source: Machinery’s Handbook milling speed and feed relations; toolmaker data governs final values.