Face Milling Formulas

Cutting Speed (vc)

• π (3.14): Circular constant
• DC (mm): Cutter diameter
• n (min^-1): Spindle speed

memo

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)

memo

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

memo

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 × 10⁶× 0.8)
= 3.937 kw
The net power required for face milling (Pc) is approximately 3.94 kW.

Kc Values