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Request A ToolUse this page as a quick reference for the relationships behind the calculators. The tables are explanatory; the exact cutting-data value should still come from the actual tool and material source.
Metric RPM
RPM = (1000 × Vc) ÷ (π × D)Vc in m/min; D in mmImperial RPM
RPM = (12 × SFM) ÷ (π × D)SFM in ft/min; D in inMilling Feed
F = RPM × Z × fzZ = flute countFeed per Rev
f/rev = F ÷ RPMKeep units consistentChip Load
fz = F ÷ (RPM × Z)Feed per toothMilling MRR
MRR ≈ F × ae × apRectangular approximationCutting Time
t = distance ÷ feedUse matching distance/feed unitsTurning Feed
F = RPM × f/revCommon turning relationshipUnit check
Write the units beside every source value. Convert before applying the equation, not after the result has already been created.
Check Dimensions Before Comparing Results
A feed per tooth in mm/tooth belongs with a metric linear feed result. For example, 0.05 mm/tooth is about 0.001969 in/tooth; retaining the number 0.05 after changing the unit would describe a different tooth feed. Keep full intermediate precision and round the result after the calculation is checked.
For removal volume, 1,000 mm/min × 5 mm × 2 mm gives 10,000 mm³/min. Dividing by 1,000 gives 10 cm³/min. The MRR guide explains the steady-cut assumption, while the chart interpretation guide helps recover the source definitions before a number reaches the calculator.
Use The Appropriate Operation Reference
Milling introduces effective teeth and engagement. Turning uses workpiece diameter and feed per revolution. Drilling connects drill diameter with penetration rate, while tapping follows thread lead. These references explain why a shared-looking feed number can represent different quantities.
Formula Reference Questions
Why Does The Metric RPM Formula Use 1000?
Cutting speed is in metres per minute while diameter is in millimetres. The factor converts metres to millimetres before relating circumference to revolutions.
How Do I Convert Cubic Millimetres To Cubic Centimetres?
Divide by 1000, because a centimetre contains 10 millimetres in each of three dimensions. For a volume rate the same conversion changes mm³/min to cm³/min.
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