Face Milling Formulas
This page introduces formulas for calculating basic parameters necessary for face milling. The figures obtained from the calculation are for reference only. The conditions for machining depend on the machine tool you are using. Use the optimal conditions according to your actual machining circumstances.
Cutting Speed (vc)
 π (3.14): Circular constant
 DC (mm): Cutter diameter
 n (min^{1}): Spindle speed
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This formula is used to calculate the cutting speed from the spindle speed and the outer diameter of the cutter.
Example:
Cutter diameter (DC) = 100 mm
Spindle speed (n) = 400 min^{1}
In this case, the cutting speed (vc) is approximately 125.6 m/min.
Feed per Tooth (f)
 vf (mm/min): Table feed per minute
 z: Number of teeth
 n (min^{1}): Spindle speed (Feed rate fr = zxfz)
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This formula is used to calculate the feed per tooth from the table feed per minute (feed rate), the number of teeth, and the spindle speed.
Example:
Table feed per minute (vf) = 450 mm/min
Number of teeth (z) = 10
Spindle speed (n) = 600 min^{1}
In this case, the feed per tooth (f) is 0.075 mm/t.
Table Feed (Vf)
 fz (mm/tooth): Feed per tooth
 z: Number of teeth
 n (min^{1}): Spindle speed (Feed rate fr = zxfz)
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This formula is used to calculate the table feed per minute (feed rate) from the feed per tooth, the number of teeth, and the spindle speed.
Example:
Feed per tooth (fz) = 0.2 mm/tooth
Number of teeth (z) = 8
Spindle speed (n) = 600 min^{1}
In this case, the table feed rate is 960 mm/min.
Machining Time (Tc)
 L (mm): Total table feed length (Length of material (l) + Face mill diameter (DC))
 vf (mm/min): Table feed per minute
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This formula is used to calculate the machining time from the total table feed length and the table feed per minute (feed rate).
Example of finishing a block of FC200 cast iron to have a flat surface of:
Width = 150 m
Length = 250 mm
Face milling conditions used:
Feed per tooth (fz) = 0.35 mm
Number of teeth (z) = 12
Spindle speed (n) = 200 min^{1}
Cutting speed (vc) = 120 m/min
Face mill diameter (D1) = 220 mm
In this case,
the table feed per minute (vf) and the total table feed length (L) are:
vf = 0.35 × 12 × 200 = 840 mm/min
L = 350 + 220 = 570 mm
Substitute these values into the formula:
Tc = L ÷ vf
= 570 ÷ 1120
= 0.679 (min) × 60
= 40.74 (sec)
The machining time (Tc) is approximately 40.74 seconds.
Net Power (Pc)
 ap (mm): Depth of cut
 ae (mm): Width of cut
 vf (mm/min): Table feed per minute
 Kc (MPa): Specific cutting force
 η: Machine efficiency
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This formula is used to calculate the net power required for face milling based on the depth and width of cut, the table feed per minute, the specific cutting force, and the machine efficiency. Example of calculating the net power required to cut tool steel with:
Depth of cut (ap) = 5 mm
Width of cut (ae) = 70 mm
Table feed per minute (vf) = 300 mm/min
Other conditions:
Specific cutting force (Kc) = 1800 MPa
Machine efficiency (η) = 80% (0.8)
Cutting speed (vc) = 80 m/min
Cutter diameter (DC) = 250 mm
Number of teeth (z) = 16
In this case, first you calculate the spindle speed (n) and then the feed per tooth of the cutter (fz).
Spindle speed (n) = 1000・vc ÷ π・D
= (1000 × 80) ÷ (3.14 × 250)
= 101.91 min^{1}
Feed per tooth (fz) = vf ÷ (Z × n)
= 300 ÷ (16 × 101.91)
= 0.184 mm/tooth
Substitute the above into the formula:
Pc = (5 × 70 × 300 × 1800) ÷ (60 × 10^{6}× 0.8)
= 3.937 kw
The net power required for face milling (Pc) is approximately 3.94 kW.
Kc Values
Workpiece material  Tensile strength (MPa) and stiffness  Specific cutting force Kc (MPa) for each feed  

0.1 (mm/tooth)  0.2 (mm/tooth)  0.3 (mm/tooth)  0.4 (mm/tooth)  0.6 (mm/tooth)  
Mild steel (SS400, S10C, etc.)  520  2200  1950  1820  1700  1580 
Medium steel (S45C, S50C, etc.)  620  1980  1800  1730  1600  1570 
Hard steel (S55C, S58C, etc.)  720  2520  2200  2040  1850  1740 
Tool steel (Carbon tool steel (SK), etc.)  670  1980  1800  1730  1700  1600 
Tool steel (Alloy tool steel (SKS), etc.)  770  2030  1800  1750  1700  1580 
Chromemanganese steel (Manganese carbide (MnC), etc.)  770  2300  2000  1880  1750  1660 
Chromemanganese steel (Manganese carbide (MnC), etc.)  630  2750  2300  2060  1800  1780 
Chrome molybdenum steel (SCM grades, etc.)  730  2540  2250  2140  2000  1800 
Chrome molybdenum steel (SCM grades, etc.)  600  2180  2000  1860  1800  1670 
Nickel chrome molybdenum steel (SNCM415, etc.)  940  2000  1800  1680  1600  1500 
Nickel chrome molybdenum steel (SNCM439, etc.)  352HB  2100  1900  1760  1700  1530 
Austenitic stainless steel (SUS304, etc.)  155HB  2030  1970  1900  1770  1710 
Cast steel (SCC, etc.)  520  2800  2500  2320  2200  2040 
Hard cast iron  46HRC  3000  2700  2500  2400  2200 
Meehanite cast iron (FC350, etc.)  360  2180  2000  1750  1600  1470 
Gray cast iron (FC250, etc.)  200HB  1750  1400  1240  1050  970 
Brass (C3710, etc.)  500  1150  950  800  700  630 
Light alloy (AlMg, A5005, etc.)  160  580  480  400  350  320 
Light alloy (AlSi, A4032, etc.)  200  700  600  490  450  390 
Light alloy (AlZnMgCu, A7075, etc.)  570  880  840  840  810  720 