# We use the following formula to calculate the desired speed of revolution:

Speed of revolution (n) = Cutting speed (Vc) x 1000 divided by 3,14 x diameter (d), where:

n = the speed of revolution in revolutions per minute,

Vc = cutting speed in meters per minute,

d = diameter in millimetres.

A different cutting speed belongs to every combination of tools and materials. The cutting speed for non-alloy steel < 800 N/mm², for example, is Vc = 23-28 m/min. For this example we will use a cutting speed of 25 m/min.

This would make the speed of revolution n:

n = (25 x 1000) / (3,14 x 12) = 25,000/37,68 = 663 revs/min.

In order to calculate the bench feed for a 12 mm milling cutter, we will use the following formula: Bench feed Bf = Feed per tooth Fz x number of teeth Z x the speed of revolution n.

__Two Flute End Mill__

Feed per tooth Fz = 0,065 mm

Number of teeth Z = 2

Bench feed Bf = 0,065 x 2 x 663 = 86 mm/min.

__Three Flute End Mill__

Feed per tooth Fz = 0,065 mm

Number of teeth Z = 3

Bench feed Bf = 0,065 x 3 x 663 = 129 mm/min.

__Four Flute End Mill__

Feed per tooth Fz = 0,06 mm

Number of teeth Z = 4

Bench feed Bf = 0,06 x 4 x 663 = 159 mm/min.

**Please note: reduce feed when drill-cutting.**