⚙️ Milling Operations

Milling Calculator Suite

Four calculators for everyday milling work. RPM and feed rate, chip load, spindle power and torque, and cycle time. Free, no login required.

Cutter Diameter *

Outside diameter of the milling cutter

Cutting Speed (Vc) *

m/min

From material / toolmaker data

Optional: Table Feed Rate

Feed per Tooth (fz)

mm/tooth

From toolmaker chip load recommendations

Number of Flutes (z)

flutes

Number of cutting edges on the cutter

Enter valid values for Cutter Diameter and Cutting Speed.

Spindle Speed (N)

RPM

⚙️

Table Feed Rate (Vf)

N/A

mm / min

Cutting Speed Input

m / min

📐

Formulas Used

N = (1000 × Vc) / (π × D) (RPM)
Vf = fz × z × N (mm/min)

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Cutting Speed Reference

Mild Steel (HSS) Vc: 20–40 m/min | fz: 0.05–0.15 mm

Mild Steel (Carbide) Vc: 80–160 m/min | fz: 0.08–0.20 mm

Aluminium Vc: 200–600 m/min (carbide) | High Vc preferred

Stainless Steel Vc: 50–100 m/min (carbide) | Keep tool engaged

Table Feed Rate (Vf) *

mm/min

Actual or planned table feed rate

Number of Flutes (z) *

flutes

Spindle Speed (N) *

RPM

Use Tool 01 to calculate RPM first

Enter valid values for all three fields.

Chip Load per Tooth (fz)

mm / tooth

🔩

📐

Formula Used

fz = Vf / (z × N) (mm/tooth)
Typical HSS: 0.01–0.05 mm | Carbide: 0.02–0.15 mm

📖

Chip Load Reference

HSS End Mills fz: 0.01–0.05 mm/tooth for steel. Exceeding this causes tool wear and chatter.

Carbide End Mills fz: 0.02–0.15 mm/tooth. Carbide needs adequate chip load to avoid rubbing.

Aluminium fz: 0.05–0.20 mm/tooth. Higher chip load to clear chips and avoid built-up edge.

Under-loading Too-low chip load causes rubbing instead of cutting. This shortens tool life faster than over-feeding.

Material Removal Rate *

cm³/min

MRR = (ae × ap × Vf) / 1000

Specific Cutting Force (Kc) *

N/mm²

Mild Steel ~1800, Alloy Steel ~2500

Machine Efficiency (η) *

Typical: 0.80–0.90 for a manual mill

Spindle Speed (N)

RPM

Required for torque calculation

Enter MRR and Specific Cutting Force at minimum.

Spindle Power Required (Ps)

⚡

Cutting Power (Pc)

Cutting Torque (Tc)

N/A

N·m

Efficiency (η)

fraction

📐

Formulas Used

Pc = (MRR × Kc) / 60000 (kW)
Ps = Pc / η (kW)
Tc = (Ps × 9550) / N (N·m)

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Power and Force Reference

Typical Kc Values Mild Steel: 1800 N/mm² | Alloy Steel: 2500 N/mm² | Aluminium: 700 N/mm²

Machine Efficiency Manual knee mills: 0.75–0.85 | CNC machining centers: 0.85–0.92

MRR Calculation MRR (cm³/min) = (ae × ap × Vf) / 1000. ae = radial depth, ap = axial depth, Vf = table feed.

Power Check Always compare Ps against the machine spindle motor rating. Running at over 80% of rated power continuously causes overheating.

Milling Type

Number of Passes *

passes

Pass Length (L) *

Approach and Overrun

Typically cutter radius + 2–5 mm

Table Feed Rate (Vf) *

mm/min

Enter Pass Length and Table Feed Rate at minimum.

Total Cycle Time

minutes

⏱️

Time per Pass

minutes

Number of Passes

passes

📐

Formulas Used

Time/pass = (L + approach) / Vf (min)
Total = Time/pass × No. of passes

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Cycle Time Reference

What is Included Pure cutting time only. Add 15–25% for tool changes, fixture adjustments, and operator time in a real quote.

Approach and Overrun For face milling: add cutter radius + 2 mm each side. For slotting: add 3–5 mm for the lead-in.

Face Milling L = part length + approach. Multiple passes needed if part width exceeds cutter diameter.

Roughing vs Finishing Calculate separately if roughing and finishing use different feed rates. Add both for total time.

👨‍🔧

Vaibhav Dhokpande

Builder, TaskJunction

Walk into any machine shop in India and you will find engineers doing RPM and feed calculations on scrap paper or from memory. The good online tools are either behind a paywall, covered in ads, or built for American and European work culture with no feel for how things actually run on the shop floor here.

I got tired of it. So I built these four calculators to cover the daily milling calculations that actually matter: spindle speed from cutting data, chip load verification, power and torque checks before you run a heavy cut, and cycle time estimates for quoting jobs. No login. No paywall. No nonsense. Put in your numbers and get your answer.

If these save even one engineer from a broken cutter or a wrong quote, the effort was worth it.

This is for the mechanical student working through a workshop assignment, the machinist at a small job shop who needs a quick check before setting up, and everyone in between. The same tools. No account needed. Works on your phone in the workshop.

If you need a calculator that does not exist on TaskJunction yet, just reach out. I am always working on the next one.

Vaibhav

taskjunction.org