How to Calculate the Right Tonnage for Your Hydraulic Press
Undersized presses cause poor cuts and premature die wear. Oversized ones waste money and floor space. This guide walks through the calculation for common Australian manufacturing applications.
Why Tonnage Matters
Tonnage is the maximum force a press can apply, measured in metric tonnes (or kilonewtons — 1 tonne ≈ 9.8 kN). Getting this right matters for two reasons:
- — Too little tonnage: The press can't complete the cut cleanly. You get tearing, incomplete cuts, and the press works at maximum capacity continuously — which accelerates wear and reduces machine life.
- — Too much tonnage: You're paying for capacity you don't use. Larger presses cost more to buy, more to run (higher power consumption), take up more floor space, and are harder to control precisely for delicate materials.
The goal is to select a press rated at 20–30% above your calculated requirement. This gives you headroom for material variation, die wear, and future applications without excessive overspecification.
The Tonnage Calculation
For die cutting (clicker presses), the required force depends on the die perimeter, material thickness, and material shear strength:
For most practical purposes, you can use simplified material factors rather than exact shear strength values:
| Material | Thickness Range | Force Factor (N/mm²) | Notes |
|---|---|---|---|
| Vegetable-tanned leather | 2–5mm | 15–25 | Varies with tannage and moisture |
| Chrome-tanned leather | 1–4mm | 10–20 | Generally softer than veg tan |
| Natural rubber | 2–6mm | 20–35 | Depends on hardness (Shore A) |
| Neoprene/synthetic rubber | 2–8mm | 15–30 | |
| EVA foam | 5–50mm | 2–5 | Very low force required |
| Polyurethane foam | 5–30mm | 3–8 | |
| Woven textile/fabric | 1–5mm | 5–15 | Depends on weave density |
| Cardboard/greyboard | 1–3mm | 15–25 | |
| Cork sheet | 2–10mm | 8–15 |
Worked Examples
Example 1: Leather Belt Blank
Example 2: Rubber Gasket
Example 3: Foam Seat Cushion
Note: thick foam requires significantly more force due to compression resistance. This is why foam cutting operations typically use large-format beam presses.
For General Hydraulic Pressing (Non-Die Cutting)
For forming, bending, pressing bearings, or straightening operations — where you're applying force to a component rather than cutting — the calculation is different and depends on the specific operation.
General guidelines for common operations:
| Operation | Typical Tonnage Range | Notes |
|---|---|---|
| Bearing press-fit (small) | 5–20 tonne | Depends on interference fit and material |
| Bearing press-fit (large) | 20–100 tonne | |
| Sheet metal forming (light) | 10–50 tonne | Depends on material and bend radius |
| Sheet metal forming (heavy) | 50–500 tonne | |
| Component straightening | 10–50 tonne | |
| Powder metal compaction | 50–500 tonne | Depends on part geometry |
For precise calculations on specific operations, consult the machine manufacturer or a mechanical engineer. The values above are starting points only.
Getting Expert Advice
If you're selecting a clicker press for die cutting in Australia, TexonOz can advise on the right ATOM model for your specific application and material. They've been matching Australian manufacturers to the right press for decades and can work through the tonnage calculation with you based on your actual dies and materials.