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Feed Rate Calculator

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When milling or drilling, or creating a tool path for a CNC machine the feed rate must be determined.  Materials have rated surface speeds for a given type of cutter.  The harder the material the slower the speed. Given the diameter of the tool and the surface speed, the RPMs of the spindle can be calculated.  Then if the tooth load for the cutter is know, and the number of teeth, the feed rate can be determined.


Units English 
Cutter Diameter:
Surface Speed:  (sfm) (See tables below)  

Spindle Speed (RPM)

Spindle Speed (RPM)
Feed/Tooth, (Tooth Load)
Number of Teeth


Feed Rate


Milling Speeds (HSS End Mills)

Material Average Tool Speed (S.F.M) 
Magnesium 300
Aluminum, 7075 300
Aluminum, 6061 280
Aluminum, 2024 200
Aluminum, Cast 134
Brass 400
Bronze 150
Copper 100
Cast Iron (soft) 80
Cast Iron (hard) 50
Mild Steel 90
Cast Steel 80
Alloy Steels (hard) 40
Tool Steel 50
Stainless Steel 60
Titanium 50
High Manganese Steel 30

S.F.M. is surface feet per min.

Drilling Speeds (HSS Drills)

Material Average Tool Speed (S.F.M) 
Magnesium 300
Aluminum 250
Brass and Bronze 200
Copper 70
Cast Iron (soft) 120
Cast Iron (hard) 80
Mild Steel 110
Cast Steel 50
Alloy Steels (hard) 60
Tool Steel 60
Stainless Steel 30
Titanium 30
High Manganese Steel 15


TOOL FEED (in/tooth)

Material End Mills

0.005 - 0.010

Aluminum 0.005 - 0.010
Brass and Bronze 0.005 - 0.010
Copper 0.004 - 0.008
Cast Iron (soft) 0.004 - 0.008
Cast Iron (hard) 0.002 - 0.006
Mild Steel 0.002 - 0.010
Cast Steel 0.002 - 0.006
Alloy Steels (hard) 0.002 - 0.006
Tool Steel 0.002 - 0.006
Stainless Steel 0.002 - 0.006
Titanium 0.002 - 0.006
High Manganese Steel 0.002 - 0.006


Design Equations:

RPM = (12 * Surface_Speed) / (PI * Cutter_Diameter)

RPM= 3.82*Surface_Speed/Cutter_Diameter

Fm = Ft x Num_Teeth x RPM, where Ft is feed/tooth, and Fm feed rate.

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