ISO 6432 mini-cylinder equivalents — SMC C85 to AirTAC MI
The verified round-body mini equivalents — with the one delta that changes depending on which bore you are replacing.
SMC’s C85 round-body minis cross-reference to AirTAC’s MI series (MIC for adjustable cushioning). Both declare conformance to ISO 6432, so for a given bore the rod thread, nose thread and mounting interface match by standard. Four things to set when you order: at Ø20 and Ø25 specify the G port (at Ø16 both are M5×0.8 and nothing changes); add S for the magnet if you are replacing a CD85; choose MIC if your SMC has air cushions; and check that nothing runs below 0.15 MPa. Seals are NBR on both sides. Overall verdict: equivalent-with-changes.
If you run an SMC CJ2, this page does not apply to you. The CJ2 is SMC’s proprietary round-body mini: it declares no ISO conformity — its catalog cites only JIS Class 2 for thread tolerance — and it is not made in Ø20 or Ø25. None of the standard-based interchange below carries over to it. A CJ2 has to be dimension-checked individually, which is a different and slower job than an ISO 6432 cross-reference.
Verified cross-references
AirTAC International Group is headquartered in Taiwan and manufactures in mainland China (Ningbo, Foshan) and Taiwan. Each card shows the side-by-side specs and cites its catalog sources.
| Spec | SMC | AirTAC | Difference |
|---|---|---|---|
| Bore | 16 mm | 16 mm | match |
| Stroke | 50 mm | 50 mm | match |
| Mounting | ISO 6432 | ISO 6432 | shared standard |
| Rod thread | M6 × 1.0 | M6 × 1.0 | match |
| Nose thread | M16 × 1.5 | M16 × 1.5 | match |
| Port thread | M5 × 0.8 | M5 × 0.8 | match — no change |
| Seal | NBR | NBR | match |
| Min. pressure | 0.1 MPa | 0.15 MPa | higher — low-pressure only |
| Max temperature | 80 °C | 70 °C | lower ceiling |
| Cushioning | Rubber std; air cushion optional | MI fixed bumper; MIC adjustable | specify MIC if yours is cushioned |
| Max piston speed | 1500 mm/s | 800 mm/s | lower — check fast cycles |
Before you substitute: Both series declare ISO 6432, so the rod thread, nose thread and mounting interface match at this bore. Add the S suffix if you are replacing a magnet-equipped CD85 — a plain MI has no magnet and your existing switch will not see the piston. If the SMC has air cushions, order MIC (adjustable cushion) rather than plain MI, which has a fixed bumper only. Check the minimum supply pressure: the AirTAC needs 0.15 MPa to move against the SMC's 0.1 MPa, so circuits regulated near 1 bar can stall. The AirTAC ceiling is 70 °C against the SMC's 80 °C, and its maximum piston speed is lower (800 vs 1500 mm/s). Seals are NBR on both sides, so media compatibility is unchanged.
Sources: SMC catalog “ISO Cylinder Series C85, ø8–ø25” — “Conforming to ISO 6432 and CETOP RP52P”; AirTAC MI/MIC catalog (rev. 2024-09-28) — “In accordance with ISO6432 standard(Φ8~Φ25)”. Verified 2026-07-28.
| Spec | SMC | AirTAC | Difference |
|---|---|---|---|
| Bore | 20 mm | 20 mm | match |
| Stroke | 50 mm | 50 mm | match |
| Mounting | ISO 6432 | ISO 6432 | shared standard |
| Rod thread | M8 × 1.25 | M8 × 1.25 | match |
| Nose thread | M22 × 1.5 | M22 × 1.5 | match |
| Port thread | G 1/8 (BSPP) | 1/8 — PT default, G optional | order G to match |
| Seal | NBR | NBR | match |
| Min. pressure | 0.1 MPa | 0.15 MPa | higher — low-pressure only |
| Max temperature | 80 °C | 70 °C | lower ceiling |
| Cushioning | Rubber std; air cushion optional | MI fixed bumper; MIC adjustable | specify MIC if yours is cushioned |
| Max piston speed | 1500 mm/s | 800 mm/s | lower — check fast cycles |
Before you substitute: Both series declare ISO 6432, so the rod thread, nose thread and mounting interface match at this bore. Add the S suffix if you are replacing a magnet-equipped CD85 — a plain MI has no magnet and your existing switch will not see the piston. If the SMC has air cushions, order MIC (adjustable cushion) rather than plain MI, which has a fixed bumper only. Check the minimum supply pressure: the AirTAC needs 0.15 MPa to move against the SMC's 0.1 MPa, so circuits regulated near 1 bar can stall. The AirTAC ceiling is 70 °C against the SMC's 80 °C, and its maximum piston speed is lower (800 vs 1500 mm/s). Seals are NBR on both sides, so media compatibility is unchanged.
Sources: SMC catalog “ISO Cylinder Series C85, ø8–ø25” — “Conforming to ISO 6432 and CETOP RP52P”; AirTAC MI/MIC catalog (rev. 2024-09-28) — “In accordance with ISO6432 standard(Φ8~Φ25)”. Verified 2026-07-28.
| Spec | SMC | AirTAC | Difference |
|---|---|---|---|
| Bore | 25 mm | 25 mm | match |
| Stroke | 100 mm | 100 mm | match |
| Mounting | ISO 6432 | ISO 6432 | shared standard |
| Rod thread | M10 × 1.25 | M10 × 1.25 | match |
| Nose thread | M22 × 1.5 | M22 × 1.5 | match |
| Port thread | G 1/8 (BSPP) | 1/8 — PT default, G optional | order G to match |
| Seal | NBR | NBR | match |
| Min. pressure | 0.1 MPa | 0.15 MPa | higher — low-pressure only |
| Max temperature | 80 °C | 70 °C | lower ceiling |
| Cushioning | Rubber std; air cushion optional | MI fixed bumper; MIC adjustable | specify MIC if yours is cushioned |
| Max piston speed | 1500 mm/s | 800 mm/s | lower — check fast cycles |
Before you substitute: Both series declare ISO 6432, so the rod thread, nose thread and mounting interface match at this bore. Add the S suffix if you are replacing a magnet-equipped CD85 — a plain MI has no magnet and your existing switch will not see the piston. If the SMC has air cushions, order MIC (adjustable cushion) rather than plain MI, which has a fixed bumper only. Check the minimum supply pressure: the AirTAC needs 0.15 MPa to move against the SMC's 0.1 MPa, so circuits regulated near 1 bar can stall. The AirTAC ceiling is 70 °C against the SMC's 80 °C, and its maximum piston speed is lower (800 vs 1500 mm/s). Seals are NBR on both sides, so media compatibility is unchanged.
Sources: SMC catalog “ISO Cylinder Series C85, ø8–ø25” — “Conforming to ISO 6432 and CETOP RP52P”; AirTAC MI/MIC catalog (rev. 2024-09-28) — “In accordance with ISO6432 standard(Φ8~Φ25)”. Verified 2026-07-28.
What ISO 6432 fixes here
As with the larger profile cylinders under ISO 15552, the standard settles the interface and leaves the rest to the manufacturer. For these minis the rod thread and nose thread match by standard at each bore — M6×1.0 and M16×1.5 at Ø16, M8×1.25 and M22×1.5 at Ø20, M10×1.25 and M22×1.5 at Ø25 — which is what makes the swap mechanically straightforward. Background: what a shared ISO standard does and does not guarantee.
The four things to set when you order
- Port thread — and this one depends on the bore.At Ø16 both sides use M5×0.8, so there is nothing to change. At Ø20 and Ø25 the SMC ships G1/8 and AirTAC’s default is a PT taper, so order the G option. This is the only family in our corpus where the port answer changes with bore, which makes it easy to get wrong by carrying an answer across from another size.
- Magnet.SMC’s magnet version is the CD85; on the AirTAC side it is the
Ssuffix. A plain MI has no magnet and your existing switch will not see the piston. AirTAC states the magnet version shares the non-magnet dimensions. - Cushioning. The C85 offers air cushions as an option. Plain MI has a fixed bumper only — order MIC for adjustable cushioning if the cylinder you are replacing is cushioned.
- Minimum pressure and speed.The AirTAC needs 0.15 MPa to move against the SMC’s 0.1 MPa, and its maximum piston speed is 800 mm/s against the SMC’s 1500 mm/s — check both if you run a fast or gently-regulated station.
The AirTAC MI series also lists Ø32 and Ø40, but AirTAC declares ISO 6432 conformance only for Ø8–Ø25. Those two larger bores are outside the standard’s scope, so treat them as a dimensional check rather than a standard-backed match. As on every page, we do not publish a cycle-life figure for either series because neither manufacturer publishes one.
Frequently asked
What is the AirTAC equivalent of an SMC C85 mini cylinder?
AirTAC's MI series (MIC for the adjustable-cushion version) is the ISO 6432 counterpart to SMC's C85. Both declare conformance to ISO 6432, so for a given bore the rod thread, nose thread and mounting interface match. It is an equivalent-with-changes: at Ø20 and Ø25 order the G port to match SMC's G1/8, add the S suffix if you need the magnet, and specify MIC if your SMC has air cushions.
Is the SMC CJ2 an ISO 6432 cylinder?
No. The CJ2 is SMC's proprietary round-body mini and declares no ISO conformity — its catalog cites only JIS Class 2 for thread tolerance — and it is not made in Ø20 or Ø25. So a CJ2 cannot be cross-referenced to an ISO 6432 cylinder on the strength of the standard. If you run a CJ2, its dimensions have to be checked individually rather than assumed from ISO 6432. The C85 is SMC's ISO 6432 series.
Do I need to change the port thread on an ISO 6432 swap?
It depends on the bore, which is unusual. At Ø16 both the SMC C85 and the AirTAC MI use M5×0.8, so there is nothing to change. At Ø20 and Ø25 the SMC ships G1/8 while AirTAC's default is a PT taper thread, so you order the G option to match. This is the one family where the port answer is not the same at every bore.
Which AirTAC bores are actually covered by ISO 6432?
AirTAC's MI catalog states conformance for Ø8 to Ø25. The series also offers Ø32 and Ø40, but those sit outside the ISO 6432 scope, so the standard-based interchange argument does not extend to them — treat those two bores as a dimensional check rather than a standard match.
Will my existing position switch work on the AirTAC?
Only if you order the magnet variant. SMC's magnet-equipped version is the CD85; on the AirTAC side the magnet is the S suffix, for example MI20×50S. A plain MI has no magnet, so an existing reed or solid-state switch will never see the piston. AirTAC states the magnet type shares the dimensions of the non-magnet type, so the swap does not change the envelope.
Sources
- SMC catalog “ISO Cylinder Series C85, ø8–ø25” — “Conforming to ISO 6432 and CETOP RP52P”; specification and dimension tables.
- SMC “Air Cylinder Series CJ2” catalog — no ISO conformity statement; JIS Class 2 cited for thread tolerance; bores 6/10/16 only. Basis for the CJ2 exclusion above.
- AirTAC “Mini cylinder (ISO6432) MI/MIC Series” catalog, rev. 2024-09-28 — “In accordance with ISO6432 standard(Φ8~Φ25)”; dimension table columns E and M; materials table.
Want a quote on the AirTAC equivalent?
Send us the SMC part you run today. We confirm the port thread for your bore, the magnet variant and the cushioning before you commit — and tell you plainly if yours is a CJ2 rather than an ISO 6432 part.