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Punch Press Force — Tonnage & Clearance

Calculate force and tonnage for punching holes in sheet metal. Force = Perimeter × Thickness × Shear Strength. Essential for press selection and tool design.

Concept Fundamentals
P × t × τ
Force
Force / 2000
Tonnage
3–8% of thickness
Clearance
1.5× factor
Safety
Calculate Punch ForceEnter hole shape, dimensions, material, and thickness.

Why This Construction Metric Matters

Why: Undersized press damages tooling; oversized wastes capital. Clearance affects hole quality and tool life. Shear strength varies by material.

How: Perimeter from shape (πD round, 2(L+W) rect). Force = P × t × shear strength. Tonnage = Force / 2000 lbs. Clearance 3–8% of thickness.

  • Mild steel ~45 ksi shear; stainless ~55–65 ksi.
  • Clearance 3–8% of thickness; too tight = burrs.
  • Add 1.5× safety factor for press selection.
  • Stripping force ~10–20% of punch force.

Punch Force Calculator

Tonnage • Clearance • Press • Tool Sizing

Quick Examples — Click to Load

Round Hole in Steel

1" diameter hole in 0.125" mild steel

Square Hole Aluminum

2" square hole in 0.25" aluminum

Slot in Stainless

3" × 0.5" slot in 0.1875" stainless

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Multiple Holes

10 × 0.5" holes in 0.1" steel

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Heavy Gauge Punch

2" round hole in 1" thick steel

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Precision Hole

0.25" round hole in 0.0625" titanium

Round Hole

Circular hole - most common shape

Perimeter: π × Diameter

📏 Hole Dimensions

🔩 Material Properties

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Mild Steel (A36)

Low carbon steel, most common

Shear: 36,000 PSIHardness: SoftClearance: 5%

⚙️ Press & Safety

Planning estimates only. Verify with a licensed engineer or contractor before construction.

📐 Construction Industry Facts

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Force = Perimeter × Thickness × Shear Strength.

— ASME

⚙️

Tonnage = Force (lbs) / 2000.

— Industry

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Clearance 3–8% of material thickness.

— Tool design

🛡️

Use 1.5× safety factor for press selection.

— Best practice

What is a Punch Force Calculator?

Determines force required to punch holes in sheet metal. Essential for press tonnage selection, punch/die design, clearance calculation.

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Press

Tonnage selection

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Tool Sizing

Punch & die

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Clearance

Die clearance

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Safety

Safety factors

How to Calculate

Force = Perimeter × Thickness × Shear Strength. Tonnage = Force / 2000.

When to Use

Sheet metal fabrication, stamping, fastener holes, design.

Why It Matters

Correct press tonnage, safe operation, proper tool sizing.

Where Applied

Metal fabrication, stamping, automotive, HVAC.

Formulas

P = πD (round) or 2(L+W) (rect). F = P × t × τ. Tonnage = F/2000.

Tips

  • • Use 1.5× safety factor
  • • Clearance 3–8% of thickness

Common Mistakes

  • • Wrong shear strength for material
  • • Forgetting to add safety factor

FAQs

Clearance %? 3–8% of thickness; varies by material.
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