Gas springs in a stamping die are usually chosen by the space they have to live in. That gets you a spring that fits. It does not get you a spring that produces the force curve the die was designed around — and the difference shows up as inconsistent stripping, short spring life, or a press that never quite runs at rate.
The Series Start From Force and Envelope
| Series | Initial force at max pressure | Envelope / mounting |
|---|---|---|
| EP3 16 / EPS3 16 | 420 N (95 lbf) | 45 + (2 × stroke); M16x1.5 / M16x2 |
| R12 / R15 / R19 | 500 / 700 / 900 N | 56–295 mm; Ø12 / Ø15 / Ø19 rod-sealed |
| EP2 24 / EPS2 24 | 1,700 N (382 lbf) | 45 + (2 × stroke); M24x1.5 |
| M2 / MM2 | 2,000 N (450 lbf) | 62–295 mm / 42 + (2 × stroke); Ø25, M28x1.5 |
Available strokes across the range run from 7 mm to 125 mm depending on series. The EP3 and EPS3 lines are color-coded gas ejector pins, designed to be interchangeable with mechanical spring plungers — which makes them a direct upgrade path where a die already has a plunger pocket.
Repairable or Replaceable
The M2 and MM2 series are built repairable. On a high-volume die, that difference matters over the life of the tool: a repairable cylinder can be serviced rather than scrapped when the seal eventually goes. On a short-run die, the economics point the other way. Pick the series with the die's total life in view, not just the first build.
Force Rises Through the Stroke
A gas spring does not deliver a flat force. Pressure rises as the piston compresses the gas, so the force at the bottom of the stroke is higher than at the top. Kaller publishes two models for this:
- An isothermal model, which assumes constant temperature through the stroke — useful for slow cycles.
- A polytropic model, which accounts for the actual stroke and used stroke, gas volume, press velocity, strokes per minute, operating temperature and internal friction.
On a fast press the polytropic model is the one that matches reality. Sizing on the isothermal figure alone is a common cause of a spring that performs on the bench and underperforms in the press.
Mounting, Briefly
Mount on the threaded holes in the base of the cylinder, never on the threaded hole in the top of the piston rod. Thread engagement should run 2 to 4 times the thread diameter, with a thread depth of at least 1.5 times the diameter in steel and 2 times in cast iron.
Where Tooling Components Fits
Tooling Components stocks the Kaller gas spring range, from the small EP3 color-coded ejector pins through the R-series rod-sealed cylinders to the repairable M2 and MM2 families. Give us the force you need at the working stroke and the envelope you have, and we will match the series, the stroke and the mounting.
Tooling Components LLC · (814) 438-7657 · [email protected]