KEVOS® MAKEOS · Fabrication
Perforated Plate Design (Hole Size for Open Area, Punching Force, Ligament)
What hole size gives my target open area at this pitch, what force does a gang of punches need, and is the ligament between holes wide enough for the sheet?
Design of a perforated sheet: the hole diameter for a target open area at a pitch for 60° staggered or straight rows, open area, holes per square metre and sheet mass for the hole you choose (as the perforated open area tool), punching force for the punches working in one hit with a wear factor (as the punching force tool) against the press, and checks of the ligament and hole size relative to the sheet thickness.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Hole pattern | choice | Layout of the holes. |
| Open area wanted | % | Open area the screen or guard needs. |
| Hole pitch | mm | Centre distance between neighbouring holes. |
| Hole diameter chosen | mm | Hole diameter you intend to use. |
| Sheet thickness | mm | Sheet thickness. |
| Sheet area | m² | Area of the perforated sheet. |
| Sheet density | kg/m³ | Density of the sheet. |
| Holes punched per hit | Number of punches that cut in one press stroke. | |
| Shear strength of the sheet | MPa | Shear strength of the sheet. |
| Wear factor | Allowance for punch and die wear. | |
| Press capacity | kN | Rated capacity of the perforating press. |
| Least ligament ÷ thickness | Least ligament width as a multiple of thickness for flatness and strength (your value). | |
| Least hole ÷ thickness | Least hole diameter as a multiple of thickness for punch life (your value). |
Method and formulas
- Open area = 90.69 (d ÷ p)² % for 60° staggered or 78.54 (d ÷ p)² % for straight rows; hole for a target = p √(OA ÷ constant) (as the perforated open area tool).
- Holes per square metre = 1.1547 ÷ p² (staggered) or 1 ÷ p² (straight); mass = area × thickness × density × (1 − open area).
- Force per hit = holes × π d × t × τ × wear factor (as the punching force tool); ligament = p − d.
- Example: 35% at a 8 mm pitch needs 4.9699 mm holes; 5 mm gives 35.426% and 169.65 kN per hit of 20 holes.
Limitations
- Full field of holes; margins and blank areas reduce the overall open area.
- Flat-faced punches; staggered punch lengths lower the peak force.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Specify a perforated screen or guard
- Check a perforating tool against the press
- Trade hole size and pitch for open area and strength
Who it is for
- Fabrication supervisors
- Design engineers
- Press tool designers
What you get
- Hole size for the target open area
- Open area, holes and mass for the hole chosen
- Punching force and the ligament and hole checks
Interpreting the result
- Narrow ligaments make the sheet distort and the punches break: keep the ligament at least the sheet thickness.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2607–2608, 1338–1346. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Perforated Plate Design (Hole Size for Open Area, Punching Force, Ligament) calculator
