1. What is a Feed and Speed Turning Calculator?

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

Purpose: Helps machinists and CNC operators calculate proper cutting speeds and feed rates for lathe operations.

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)
• \( FR \) — Feed rate (inches per minute)
• \( IPR \) — Inches per revolution (feed 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 Feed and Speed

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

4. Using the Calculator

Tips:

• SFM depends on material (e.g., 100-300 for aluminum, 50-150 for mild steel)
• IPR depends on tool and operation (0.005-0.020 for roughing, 0.002-0.010 for finishing)
• All values must be > 0

5. Frequently Asked Questions (FAQ)

Q1: What's the 3.82 constant in the RPM formula?
A: It's the conversion factor from SFM to RPM (12/π ≈ 3.82) when diameter is in inches.

Q2: How do I determine the right SFM?
A: Consult tooling manufacturer recommendations or material-specific machining guides.

Q3: What's a typical IPR for turning?
A: Common ranges are 0.005-0.020" for roughing and 0.002-0.010" for finishing, depending on material and tool.

Q4: Does this work for metric units?
A: No, this calculator uses imperial units. For metric, use: RPM = (meters/min × 1000) / (π × mm diameter).

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.