Milling Cutter Speeds Feeds Calculator

Milling Formulas:

\[ RPM = \frac{SFM \times 3.82}{D} \] \[ Feed = RPM \times \text{chip load} \times \text{teeth} \]

SFM (surface feet/min):

ft/min

Diameter (D):

inches

Chip Load:

inches/tooth

Number of Teeth:

teeth

RPM:

Feed Rate:

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1. What is Milling Speed and Feed?

Milling speed (RPM) and feed rate are critical parameters in machining operations that determine how fast the cutter rotates and how fast it moves through the material. Proper settings ensure efficient material removal while maintaining tool life and surface finish.

2. How Does the Calculator Work?

The calculator uses these fundamental milling formulas:

\[ RPM = \frac{SFM \times 3.82}{D} \] \[ Feed = RPM \times \text{chip load} \times \text{teeth} \]

Where:

\( RPM \) — Revolutions per minute of the cutter
\( SFM \) — Surface feet per minute (cutting speed)
\( D \) — Cutter diameter in inches
\( Feed \) — Table feed rate in inches per minute
\( Chip Load \) — Feed per tooth in inches
\( Teeth \) — Number of cutting teeth on the tool

Explanation: The 3.82 constant converts SFM to RPM for a given diameter. Feed rate depends on how much material each tooth removes per revolution.

3. Importance of Proper Speeds and Feeds

Details: Correct speeds and feeds prevent tool breakage, minimize wear, optimize surface finish, and maximize material removal rates. Too slow causes rubbing and tool wear; too fast causes overheating and breakage.

4. Using the Calculator

Tips: Enter SFM based on material being cut (see reference charts), tool diameter, recommended chip load for your tool/material, and number of teeth on your cutter.

5. Frequently Asked Questions (FAQ)

Q1: What are typical SFM values?
A: Varies by material: Aluminum 250-500 SFM, Steel 100-300 SFM, Titanium 50-150 SFM. Always consult tool manufacturer recommendations.

Q2: How do I determine chip load?
A: Chip load depends on tool material, workpiece material, and rigidity. Start with manufacturer recommendations (typically 0.001-0.010 in/tooth for small end mills).

Q3: What if my machine can't reach calculated RPM?
A: Use maximum available RPM and adjust feed proportionally to maintain proper chip load.

Q4: How does tool coating affect speeds?
A: Advanced coatings (TiAlN, etc.) often allow higher SFM values (20-50% more than uncoated tools).

Q5: Should I adjust for slotting vs. peripheral milling?
A: Yes, slotting typically requires 20-30% reduction in feed rate compared to peripheral milling.