Formula Used
Feed rate: F = N × Z × fz
Feed per revolution: F_rev = Z × fz
Metric spindle speed: N = 1000 × Vc ÷ πD
Inch spindle speed: N = 12 × SFM ÷ πD
Material removal rate: MRR = F × ae × ap
Metric power estimate: kW = Kc × MRR ÷ 60,000,000
Inch power estimate: hp = MRR × unit horsepower
When chip thinning is active, the calculator raises programmed chip load
for small radial engagement. The correction is only applied when radial
depth is below half of cutter diameter.
How To Use This Calculator
- Select metric or inch units.
- Choose whether spindle speed is known or calculated from cutting speed.
- Enter cutter diameter, teeth, chip load, and depth values.
- Add cutting force or unit horsepower for power estimation.
- Enable chip thinning for low step-over milling paths.
- Press calculate to view results above the form.
- Download CSV or PDF for setup records.
Example Data Table
| Material |
Cutter Diameter |
Teeth |
RPM |
Chip Load |
Feed Rate |
| Aluminum |
10 mm |
3 |
6000 |
0.05 mm/tooth |
900 mm/min |
| Mild Steel |
12 mm |
4 |
2500 |
0.035 mm/tooth |
350 mm/min |
| Plastic |
0.25 in |
2 |
12000 |
0.003 in/tooth |
72 in/min |
Why Milling Feed Rate Matters
Milling feed rate controls how fast the cutter moves through material. It links spindle speed, chip load, and cutter teeth into one useful number. A correct feed protects the tool. It also improves surface finish and keeps cycle time realistic. Too little feed can rub the work. Too much feed can overload the cutter, spindle, or fixture.
Physics Behind the Cut
Every tooth removes a small chip. That chip has thickness, width, and length. The machine must supply force to shear it away. Feed rate decides how much material each tooth meets during every revolution. Cutter diameter affects surface speed. Radial and axial depth affect material removal rate. These values help estimate heat, power, and chip flow.
Practical Shop Benefits
This calculator supports both metric and inch units. You can enter a known spindle speed. You can also derive speed from cutting speed and diameter. The tool then finds feed per minute, feed per revolution, surface speed, removal rate, and estimated power. Optional radial chip thinning helps when step-over is small. This is useful for high-efficiency toolpaths.
Choosing Input Values
Start with the cutter supplier’s chip load range. Use the lower side for weak setups, long tools, or hard materials. Use the higher side for rigid machines and stable holders. Enter the actual flute count. Count only cutting teeth that engage the material. Use realistic depth values. A deep axial cut with wide engagement needs more power than a light finishing pass.
Interpreting Results
The recommended feed is a planning value. Listen to the cut after setup. Chips should form cleanly. The sound should stay steady. Watch spindle load and tool wear. Reduce feed when chatter, poor finish, or heavy burrs appear. Increase feed only when the process remains stable.
Better Process Control
Exported results can support setup sheets, job notes, and repeat work. A saved record helps compare tools and materials. It also reduces guesswork between operators. Use the example table as a quick check. Then adjust values for your cutter, machine, coolant, and workholding. Keep notes on tool coating, coolant style, and holder length. These details explain many feed changes and make future milling estimates more dependable. Small records prevent repeated mistakes.
FAQs
What is milling feed rate?
Milling feed rate is the linear speed of the cutter through the workpiece. It is usually shown as millimeters per minute or inches per minute.
What is chip load?
Chip load is the material thickness removed by each cutting tooth. Correct chip load helps avoid rubbing, heat, tool breakage, and poor finish.
Can I calculate RPM from cutting speed?
Yes. Select the cutting speed mode. Then enter cutter diameter and cutting speed. The calculator will derive spindle speed before finding feed rate.
What does radial chip thinning mean?
Radial chip thinning happens when step-over is small. The chip becomes thinner, so programmed feed can often increase while keeping target chip thickness.
Should I always use the calculated feed?
No. Treat it as a starting value. Reduce feed for chatter, weak fixtures, long tools, poor coolant, or hard spots in the material.
What is material removal rate?
Material removal rate estimates how much material is cut each minute. It uses feed rate, radial depth, and axial depth of cut.
Why is power estimation included?
Power estimation helps check whether the machine can handle the planned cut. It is approximate and depends on material data and machine efficiency.
Can this calculator be used for finishing cuts?
Yes. Use light depth values and suitable chip load. Finishing often needs stable feed, sharp tools, and low runout for better surface quality.