1. What is a Punching Tonnage Calculator?

Definition: This calculator estimates the force required to punch through sheet metal based on material properties and punch geometry.

Purpose: It helps metal fabricators select appropriate press brake tonnage for punching operations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The formula calculates the total force required to shear the material along the punch perimeter.

3. Importance of Punching Tonnage Calculation

Details: Proper tonnage estimation ensures successful punching operations, prevents machine overload, and maintains tooling life.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What's the 2000 divisor for?
A: It converts pounds to tons (1 ton = 2000 lbs).

Q2: How do I measure punch perimeter?
A: For round punches: π × diameter. For other shapes, sum all side lengths.

Q3: What's typical shear strength for common materials?
A: Mild steel: 45,000 psi; Aluminum: 25,000 psi; Stainless: 65,000 psi.

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

Q5: Does this account for die clearance?
A: No, this is basic tonnage. Additional factors like clearance may affect actual requirements.