A pneumatic cylinder built to an ISO standard can usually be replaced with another maker’s cylinder to the same standard, on the same mountings. The standard fixes the interface, not the whole cylinder. Knowing which of the three common standards a cylinder follows, and what each one leaves open, decides whether a swap is a quick job or a modification.
Three standards side by side
| Standard | Cylinder | Bore sizes | Examples |
|---|---|---|---|
| ISO 15552 | Profile or tie-rod cylinder with detachable mountings | 32 to 320 mm | Festo DSBC, SMC CP96 |
| ISO 6432 | Round mini cylinder | 8 to 25 mm | Festo DSNU, SMC C85 |
| ISO 21287 | Compact cylinder | 20 to 100 mm | Festo ADN, SMC C55 |
ISO 15552 replaced ISO 6431 and the German VDMA 24562, so an older drawing may name either of them. All three standards cover cylinders for a working pressure of up to 10 bar.
What the standard fixes
Within one standard and one bore, cylinders from different makers share the dimensions that meet the machine: the mounting interface, the piston rod thread and the ports. A foot mounting, a clevis or a rod-end fitting made for an ISO 15552 cylinder fits any ISO 15552 cylinder of that bore. Order the same stroke, and check the stroke tolerance if the end positions matter.
What it leaves open
- Cushioning: elastic, pneumatic adjustable or self-adjusting, with different cushioning lengths. A cylinder that stopped softly may hit the end hard with another type.
- Position sensing: the sensor slot and the sensors that fit it are the maker’s own. Plan new sensors, or adapters, along with the cylinder.
- Seals and temperature range: standard seals, low-friction seals or versions for heat, cold or food areas.
- Piston rod: its material, a through rod or a non-rotating rod, each ordered as a variant.
Cylinders outside the standards
Many compact and short-stroke cylinders follow no ISO standard at all. Festo’s ADVU and SMC’s CQ2 are examples: well-known ranges built to each maker’s own dimensions. A replacement from another maker then needs an adapter plate or new holes. If the old cylinder’s data sheet gives no ISO reference, assume it is one of these and replace it from the same range.
Ordering the replacement
Put the standard, the bore, the stroke, the cushioning and the sensors in the request, together with the old ordering code. Festo and SMC ordering codes carry the bore and the stroke, so a request with the full code is quicker to answer: DSBC-50-100-PPVA-N3 is a cylinder with a 50 mm bore and a 100 mm stroke. Search the code first, or send one request for quotes for every cylinder on the list.