Press Tonnage Reference Chart
Required press force follows directly from compaction pressure and the projected area of the part:
F = P × A
where F is force, P is the compaction pressure the material needs, and A is the area of the part seen along the pressing axis. The table below works that arithmetic for round parts at three common compaction pressures.
Required force by part diameter (round parts, tonnes)
| Part diameter | Projected area (mm²) | at 20 MPa | at 25 MPa | at 35 MPa |
|---|---|---|---|---|
| 25 mm | 491 | 1.0 | 1.3 | 1.8 |
| 50 mm | 1,963 | 4.0 | 5.0 | 7.0 |
| 75 mm | 4,418 | 9.0 | 11.3 | 15.8 |
| 100 mm | 7,854 | 16.0 | 20.0 | 28.0 |
| 150 mm | 17,671 | 36.0 | 45.0 | 63.1 |
| 200 mm | 31,416 | 64.1 | 80.1 | 112.1 |
| 250 mm | 49,087 | 100.1 | 125.1 | 175.2 |
| 300 mm | 70,686 | 144.2 | 180.2 | 252.3 |
| 400 mm | 125,664 | 256.3 | 320.3 | 448.5 |
| 500 mm | 196,350 | 400.4 | 500.5 | 700.7 |
How to use it
- Take the compaction pressure from the material datasheet. General-purpose PTFE moulding powder typically needs somewhere around 20–25 MPa; filled grades, ceramics and metal powders differ, often substantially.
- Calculate the projected area of your part along the pressing axis. For a non-round part, use the actual outline area, not the bounding rectangle.
- Multiply. Then add a margin — a press running permanently at its rated capacity has no headroom for a harder powder batch or a larger future part.
- For multi-cavity tooling, sum the projected area of every cavity.
What the chart does not tell you
Tonnage alone does not specify a press. Daylight, stroke, platen size, the number of independently controlled punch motions, and the fill and dwell profile all follow from the part and the material. A 100-tonne press correctly sized on force can still be the wrong machine if the daylight will not accept the tool.
Send the part drawing and the powder grade rather than a tonnage figure, and the calculation can be done against your actual part.
Related references
The terms used above — projected area, compaction pressure, density gradient — are defined in the powder compaction glossary.
Compaction pressure is material-specific, and each family behaves differently: PTFE powder needs a slow stroke because it traps air, while metal powder is governed by die-wall friction and ejection force.
For machine selection once the force is known, see powder compaction presses and compression moulding presses, or send the part drawing to HEMSUN.