Punch Force Calculator

Tool & Die Engineering & Sheet Metal Stamping Mechanics

In manufacturing stamping dies, turret punch presses, and CNC ironworkers, Punching Force represents the peak shearing resistance overcome as the punch tool penetrates through sheet metal stock.

Core Punch Press Equations

• Circular Hole Perimeter: L = π × d

• Rectangular Slot Perimeter: L = 2 ×

• Shearing Force: F = L × t × τ = Perimeter (mm) × Thickness (mm) × Shear Strength (MPa)

• Press Tonnage (US Short Tons): Tonnage = F (Newtons)8,896.44 = F (kN)8.89644

• Stripping Force: F_strip ≈ 0.10 to 0.15 × F_punch

• Press Tonnage Safety Factor: Tonnage_press = Tonnage_calculated × 1.30

Material Shear Strengths (τ)

• Mild Steel / Low Carbon (1018, A36): ~300 to 380 MPa

• Stainless Steel (304, 316): ~450 to 550 MPa

• Aluminum Alloys (5052, 6061-T6): ~150 to 220 MPa

• Brass & Copper: ~220 to 280 MPa.

How to Use This Calculator

Enter your Application Domain — choose from Industrial Sheet Metal Stamping / Die Punching (F = L × t × τ), Combat Sports / Martial Arts Boxing Strike (F = m × v ÷ Δt), Punch Die Geometry (Metal Mode) — choose from Round Circular Hole (Perimeter = π × d), Rectangular / Square Slot (Perimeter = 2 × (L + W)), Custom Perimeter Length (Direct Entry), Hole Diameter / Length (mm) (e.g. 25.0 in mm), Hole Width (mm, if Rectangular) (e.g. 15.0 in mm), Sheet Metal Thickness (t in mm) (e.g. 2.0 in mm), Sheet Metal Material Type — choose from Low Carbon / Mild Steel (Shear Strength: 350 MPa), Stainless Steel 304/316 (Shear Strength: 500 MPa), Aluminum Alloy 5052/6061 (Shear Strength: 200 MPa), Effective Striker Mass (kg, for Boxing) (e.g. 5.0 in kg), and Punch Velocity (m/s, for Boxing) (e.g. 9.0 in m/s). Verify your units match the formula standard (SI vs imperial) before entering values.

The Formula

F (N) = L (mm) t (mm) Shear Strength (N/mm2 or MPa)

Boxing impact F = (m * v) / dt (dt ~ 0.015 s contact duration)

Worked Example

Punching a 25mm diameter hole in 2.0mm mild steel (350 MPa): Requires 54.98 kN of force (6.18 US Tons) with 6.60 kN stripping force on an 8-9 ton press machine.

Understanding Your Result

Force in Newtons (N): 1 N = 1 kg·m/s². Reference values: 1 kg object at Earth's surface weighs 9.81 N, atmospheric pressure 101,325 Pa (N/m²). Pressure benchmarks: car tire 30–35 psi (207–241 kPa), blood pressure systolic 120 mmHg (16 kPa), deep sea at 3,000m depth ~300 atm (30 MPa). Torque = Force × moment arm length — doubling the wrench length doubles the torque for the same applied force. Always verify whether gauge or absolute pressure is required for the application.