1. What is a Speed and Feed Calculator for Turning?

Definition: This calculator determines the optimal spindle speed (RPM) and feed rate (IPM) for turning operations based on material properties and tool characteristics.

Purpose: It helps machinists and CNC operators select appropriate cutting parameters for efficient and safe turning operations.

2. How Does the Calculator Work?

The calculator uses these formulas:

Where:

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

Explanation: The SFM is converted to RPM based on workpiece diameter, then multiplied by IPR to determine the linear feed rate.

3. Importance of Proper Speed and Feed

Details: Correct RPM and IPM settings ensure optimal tool life, surface finish, and material removal rates while preventing tool breakage or workpiece damage.

4. Using the Calculator

Tips: Enter the SFM (based on material), workpiece diameter, and IPR (based on tool and operation). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical SFM for common materials?
A: Aluminum: 250-500 SFM, Mild Steel: 100-300 SFM, Stainless Steel: 50-150 SFM (varies by tool material and condition).

Q2: Why is the constant 3.82 used in the formula?
A: It's derived from (12 inches/foot) ÷ π (≈3.1416) to convert SFM to RPM for a given diameter.

Q3: What IPR should I use?
A: Roughing: 0.010-0.020 in/rev, Finishing: 0.003-0.010 in/rev (depends on tool and material).

Q4: How does diameter affect RPM?
A: Smaller diameters require higher RPM to maintain the same SFM, while larger diameters need lower RPM.

Q5: Should I adjust for tool wear?
A: Yes, as tools wear, you may need to reduce SFM by 10-20% to maintain tool life.