General Speeds and Feeds Formulas
December 24, 2010, 2:10 pmArticle Summary
Eldar Gerfanov
December 24, 2010, 2:10 pm
Eldar Gerfanov
September 30, 2019, 1:11 am
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Author Summary
Wed May 12, 2021, 10:26 am
Wed May 12, 2021, 10:26 am
Free Online Speed and Feed Calculators
Imperial Speed and Feed Calculator
| RPM= | 12 x SFM | = Please enter Speed and Diameter |
| 3.14 x in |
Feed Rate = RPM x x in = Please enter RPM, number of teeth and chip load (in/min)
Feed Rate = RPM x x mm = Please enter RPM, number of teeth and chip load (mm/min)Metric Speed and Feed Calculator
RPM=
1000 x M/min
= Please enter Speed and Diameter
3.14 x mm
Want something better?
Try our desktop HSMAdvisor Speed and Feed Calc or Mobile/Online FSWizard
More about formulas needed to calculate turning, drilling and of course milling speeds and feeds
Here are few basic formulas with term explanations to get you going:
Calculating Spindle Speed (RPM) Using Imperial Cutting Speed:
Simplified imperial formula:
RPM=
12 x SFM
3.14 x Diameter
RPM=
3.8 x SFM
Diameter
Calculating Spindle Speed (RPM) using Metric Cutting Speed:
Simplified metric formula:
RPM=
1000 x SMM
3.14 x Diameter
RPM=
318 x SMM
Diameter
Calculating Feed Rate :
Feed_Rate=RPM x N(teeth) x CL(chip load)
Definitions
- RPM = Revolutions Per Minute, Spindle Speed, Number of revolutions of spindle per minute
- SFM = Imperial. Surface Feet Per minute, Cutting speed, Speed at which tip of tool travels through material
- SMM= Metric. Surface Meters Per minute, Cutting speed, Speed at which tip of tool travels through material
- Feed_Rate = Inches Per Minute or Millimeters Per Minute, Feed Rate, Distance in inches or millimeters the tool the will travel through work piece per minute.
- N = Number of teeth on the cutter
- CL= Chip Load per tooth, This is the advancement of the cutter per revolution per each cutting edge. Otherwise generally explained as thickness of material each tooth takes per each revolution
Examples:
Calculate Speeds and Feeds for 1/2" (0.5 inch) 2 flute end mill in Mild Steel at cutting speed = 100(ft/min), Chip Load=0.001(inch per tooth)
Calculating Spindle Speed (RPM):
=
RPM=
12 x SFM
3.14 x Diameter
RPM=
12 x 100(ft/min)
=764(revs/min-1)
3.14 x 0.5(in)
For turning applications we do not need this formula since Spindle Speed is usually given in Constant Surface Speed (CSS), which uses SFM value directly. But if you still want to use RPM formula, then diameter value is the actual diameter of work piece.
Calculating Feed Rate in Inches Per Minute (IPM)
Formula used for milling and drilling applications. Please note that some tool manufacturers provide their recommended feed rate as feed per revolution. In such case do not multiply by number of teeth.
Feed Rate = RPM x N x CL
Feed Rate = 800(RPM) x 2(teeth) x 0.001("chip load) =1.600 (in/min)
Easily Calculating Speeds and Feeds on your smartphone or computer
Our own free Speed and Feed Calculator can help you calculate cutting parameters for many different material groups.
