1. What is a HSS Drill Bit Feed and Speed Calculator?

Definition: This calculator determines the optimal rotational speed (RPM) and feed rate (IPM) for drilling with High-Speed Steel (HSS) bits.

Purpose: It helps machinists and metalworkers achieve efficient material removal while extending tool life.

2. How Does the Calculator Work?

The calculator uses these formulas:

Where:

• \( RPM \) — Spindle speed (revolutions per minute)
• \( SFM_{hss} \) — Surface feet per minute for HSS material
• \( D \) — Drill 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. Feed rate is then calculated based on the desired chip load.

3. Importance of Proper Feed and Speed

Details: Correct RPM and feed rates prevent tool breakage, reduce heat buildup, improve surface finish, and maximize tool life.

4. Using the Calculator

Tips: Enter the SFM for your material (default 100 for mild steel with HSS), drill diameter, and desired feed per revolution (default 0.010").

5. Frequently Asked Questions (FAQ)

Q1: What are typical SFM values for HSS drills?
A: Mild steel: 80-120 SFM, Aluminum: 200-300 SFM, Stainless steel: 30-60 SFM.

Q2: How do I determine IPR?
A: Start with 0.001-0.002" per diameter inch (e.g., 0.010" for 1/2" drill), adjust based on material.

Q3: Why does RPM decrease as diameter increases?
A: Larger diameters have greater circumference, so they must rotate slower to maintain the same surface speed.

Q4: When should I reduce the calculated values?
A: For deep holes, hard materials, or when using older machinery, reduce by 20-30%.

Q5: How does this differ for carbide drills?
A: Carbide can run 2-3 times faster than HSS - use appropriate SFM values for carbide.