1. What is a Hole Punch Tonnage Calculator?

Definition: This calculator estimates the force required to punch a hole through metal based on material properties and punch dimensions.

Purpose: It helps metal fabricators determine the appropriate press brake or punch press capacity needed for specific hole punching operations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( T \) — Required tonnage (tons)
• \( P \) — Perimeter of punch (inches)
• \( t \) — Material thickness (inches)
• \( S \) — Shear strength of material (psi)

Explanation: The formula calculates the total force needed by considering the cutting length (perimeter), material thickness, and resistance to shearing.

3. Importance of Tonnage Calculation

Details: Accurate tonnage estimation ensures proper equipment selection, prevents machine overloading, and helps achieve clean cuts without tool damage.

4. Using the Calculator

Tips: Enter the punch perimeter (circumference for round holes), material thickness, and shear strength (default 45,000 psi for mild steel). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I calculate perimeter for non-round punches?
A: For square/rectangle punches: P = 2 × (length + width). For complex shapes, sum all side lengths.

Q2: What's the shear strength for common materials?
A: Mild steel ~45,000 psi, Stainless steel ~65,000 psi, Aluminum ~25,000 psi.

Q3: Why divide by 2000 in the formula?
A: This converts pounds-force (result of P×t×S) to tons (2000 lbs = 1 ton).

Q4: Should I add a safety factor?
A: Yes, consider adding 20-30% to the calculated tonnage for tool wear and material variations.

Q5: How does material hardness affect tonnage?
A: Harder materials require more tonnage. Use higher shear strength values for hardened metals.