Speed 1 = 300

Tool Life @ Speed 1 = 10

Speed 2 = 200

Tool Life @ Speed 2 = 50

n =

C [sfpm@1min. tool life] =

Speed 3 =

New Tool Life =

Desired Tool Life =

New Speed =

A milling or lathe (turning) machine tool will last for a certain amount of time under specific conditions. The largest factor affecting the life of a tool is the speed at which the cutter is being driven through the material.

The speed is measured in units if surface feet per minute. On a lathe, the rpm of the work piece (material being cut) is adjusted based on its diameter. For a mill, the rpm of the tool is adjusted based on the diameter of the cutting tool to reach the correct surface speed. A smaller tool must spin faster than a larger tool for a given surface speed.

The Taylor's Equation for Tool Life Expectancy provides a good approximation for how long a milling or turning tool will last.

A general form of the equation is

C=VT^n

V=cutting speed (sfpm)

T=tool life (min.)

C=cutting speed for 1 minute tool life

n=exponent

n and C are constants found by experimentation or published data; they are properties of tool material, workpiece and feed rate.

To find n and C for a given machining and material condition, measure tool life at one speed, and then measure tool life for a second speed. Enter the values into this calculator.

Make sure you push all the equal signs to update the calculation each time you make a change.

Contributed by jeffsowden

Say, at a speed of 300 sfpm, tool life is 10 minutes and at the speed of 200 sfpm, tool life is now 50 minutes.

Enter these values to see what the n and C values are. Enter a new speed for speed 3 to see what the new tool life is.

Or enter a new time for Desired Tool Life and see what the required speed is for that tool life.

Speed 1

Tool Life @ Speed 1

Speed 2

Tool Life @ Speed 2

n

C [sfpm@1min. tool life]

Speed 3

New Tool Life

Desired Tool Life

New Speed

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