Compute loads from strength, thickness, and perimeter. See pressure on the punch face with conversions. Plan press capacity, safety margin, and clear reports fast.
| Material | τ (MPa) | Thickness (mm) | Punch type | Size | Force (kN) | Pressure (MPa) |
|---|---|---|---|---|---|---|
| Mild steel (approx.) | 250 | 2 | Circular | d = 10 mm | 15.708 | 200.000 |
| Aluminum alloy (approx.) | 140 | 1.5 | Rectangular | 20×10 mm | 12.600 | 63.000 |
| Stainless steel (approx.) | 320 | 3 | Custom | L = 80 mm, A = 200 mm² | 76.800 | 384.000 |
Examples are illustrative; always validate with material datasheets and tooling guidance.
Punching removes material by shearing along the cutting edge. The key idea is that the shear area equals thickness times perimeter.
Here, τ is shear strength, t thickness, L perimeter, A punch face area, s stripping %, SF safety factor, and η efficiency.
Punching pressure describes how intensely the punch face loads the work during a cut. This calculator reports pressure as force divided by punch face area, giving MPa (N/mm²) and psi. High pressure can accelerate punch wear, increase galling risk, and demand better lubrication and alignment.
Shear strength (τ) is the main driver of punching force. For quick estimates, many steels use τ near 0.55–0.65 of ultimate tensile strength. Aluminum alloys often sit around 100–200 MPa, mild steels around 200–300 MPa, and many stainless grades around 250–400 MPa, depending on temper and heat treatment.
Force grows linearly with sheet thickness because the sheared area is thickness times perimeter. Doubling thickness doubles the predicted cutting force. Thickness also influences recommended die clearance, burr formation, and edge rollover. Production setups often tune clearance as a percentage of thickness to balance force, edge quality, and tool life.
Perimeter (L) is the cutting edge length in contact with the sheet. A circular hole uses L = πd, while a rectangle uses L = 2(w + h). Complex profiles can be handled by entering custom perimeter. Larger perimeter increases force even if hole area stays similar, which is why slender slots often require higher tonnage than expected.
Real presses must overcome stripping and friction when the punch withdraws. A common planning range is 5–20% extra force, depending on material, lubrication, surface finish, and tool condition. The calculator applies stripping as a percentage increase, so you can compare conservative and aggressive assumptions quickly.
Safety factor helps cover uncertainty in material properties, thickness tolerance, edge radius, misalignment, and wear. Values around 1.1–1.5 are typical for early estimates, while demanding production lines may justify higher margins. In this calculator, safety factor multiplies the base force after stripping is applied.
Rated press capacity is not always fully available at the working point. Mechanical losses, drive condition, and setup stiffness reduce effective force. This calculator converts augmented force into required press capacity by dividing by efficiency (η). Example: η = 0.85 implies the press must be sized about 18% higher than augmented force.
Use material data from a datasheet when possible, and verify thickness in production units. For best results, keep punches sharp, maintain proper alignment, and select clearance suitable for the material and thickness. Track force trends; a steady rise can indicate dull tooling, poor lubrication, or increasing friction.
Shear strength, sheet thickness, and perimeter dominate. Force scales linearly with each. Increasing thickness or perimeter by 10% increases base force by about 10%, assuming the same material strength.
Force is the total cutting load. Pressure divides that load by the punch face area. Two punches can need the same force but show different pressures if their face areas differ.
Start with 5–10% for well-lubricated, clean materials and sharp tools. Use 10–20% if surfaces are rough, lubrication is limited, or stripping is difficult. Validate against shop measurements when available.
For preliminary sizing, 1.1–1.3 is common. Use higher values when material properties vary, tooling is worn, or alignment is uncertain. If you have production data, base the factor on observed peak loads.
Efficiency accounts for losses and how much rated capacity is effectively delivered. If efficiency is 0.85, the calculator increases required capacity so the press can reliably meet the augmented load at the working point.
Yes. Select the custom option and enter total perimeter and punch face area. Ensure the perimeter includes all cutting edges. For very intricate profiles, compute perimeter from CAD for best accuracy.
They are engineering estimates. Tool sharpness, clearance, lubrication, temperature, and machine stiffness can change real loads. Use these results for planning, then confirm with trial runs and monitoring.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.