1. What is Turning Feeds and Speeds Calculator?

Definition: This calculator determines the optimal rotational speed (RPM) and feed rate (IPM) for turning operations based on material, tool, and diameter.

Purpose: It helps machinists and CNC operators set up lathes correctly for efficient material removal and good surface finish.

2. How Does the Calculator Work?

The calculator uses two fundamental formulas:

Where:

• \( RPM \) — Spindle speed (revolutions per minute)
• \( SFM \) — Surface feet per minute (cutting speed)
• \( D \) — Workpiece diameter (inches)
• \( IPM \) — Feed rate (inches per minute)
• \( IPR \) — Feed per revolution (inches per revolution)

Explanation: The 3.82 constant converts SFM to RPM for a given diameter. IPM combines RPM with the desired feed per revolution.

3. Importance of Proper Feeds and Speeds

Details: Correct settings prevent tool wear, improve surface finish, optimize cycle times, and avoid workpiece damage or machine overload.

4. Using the Calculator

Tips: Enter the recommended SFM for your material/tool combination, workpiece diameter, and desired feed per revolution (chip load).

5. Frequently Asked Questions (FAQ)

Q1: Where do I find SFM values?
A: Consult tooling manufacturer recommendations or material machining guides. Common SFM ranges: 100-200 for aluminum, 50-100 for mild steel.

Q2: What's a typical IPR value?
A: Depends on material and tool, but often 0.005-0.020 in/rev for roughing, 0.002-0.010 in/rev for finishing.

Q3: Does diameter affect calculations?
A: Yes! Smaller diameters require higher RPM to maintain the same SFM. Always recalculate when changing diameters.

Q4: Should I use calculated RPM exactly?
A: Round to nearest available machine RPM. For CNC, use exact value if within machine capability.

Q5: How do I adjust for different materials?
A: Change the SFM value based on material hardness. Harder materials generally require lower SFM.