#1 Approach length for plain milling cutter:

Approach “A” for a plain milling cutter can be determined by the equation:


  • A = the approach in mm.
  • B = the depth of cut in mm.
  • C = the diameter of the cutter in mm.

#2 Approach length for face milling cutter:

Referring to the above figure, the approach length for a face milling cutter can be calculated from the equation


  • A = it is the length of approach in mm.
  • D = it is the cutter diameter.
  • B = it is the width of the work.
  • Substituting the value of “C” in equation “A”

Average Cutting Speed and Feed of Different Materials

Let’s Consider One Example

#1 Example

Evaluate the cutting parameters for the slab milling operation for the following date:

  • Milling cutter diameter = 100 mm
  • Cutter speed = 500 r.p.m
  • Width of cutter = 100 mm
  • Depth of cut = 5mm
  • Table feed = 100 mm/min
  • Length of workpiece = 50 cm
  • Width of workpiece = 80 mm
  • Number of teeth in cutter = 8

Ans: Cutter diameter = 100 mm, cutter speed = 500

MRR = b.d.F

b = width of job = 80 mm, d = depth of cut = 5 mm, F = Table feed = 100 mm/min.


= 500 mm, Here y = 4 mm


This is a complete list of milling formulas and definitions that are useful in any milling process and milling cutter. Understanding how to calculate accurate cutting speed, feed per tooth, or metal removal rate and machining time is very important for good results in any milling operation.