This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40X8, with the same bore, stroke, output force, port and mounting, so it fits the same application. The SAI replacement keeps the same ISO 15552 mounting interface, bore, stroke, output force and accessories, so it drops straight into existing fixtures. It is the current-production version of this cylinder with an upgraded piston seal.
Airtac SI40 Standard Cylinder SI40X8
The AirTAC Airtac SI40 Standard Cylinder SI40X8 is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 8mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40X8, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke8 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40X8
- No minimum order. A single piece can be ordered.
- Ready in 3–5 business days. That is the time we take to process the order and hand it to the carrier. Transit time after that depends on the destination.
About the Airtac SI40 Standard Cylinder SI40X8
The AirTAC SI40X8 is a discontinued double-acting ISO 15552 profile cylinder with an 8 mm stroke and 40 mm bore, delivering 628 N push force at 0.5 MPa. It is superseded by the SAI40X8 direct replacement, which shares the exact ISO 15552 mounting interface, G1/4 port, and M12x1.25 rod thread. The SAI upgrade features a new piston seal with two Y-shaped one-way elements for lower start-up pressure and longer life. With no -S suffix, this SKU cannot accept a magnetic sensor.
The SAI family also introduces SAIL, SAIF, and BSAI lock variants absent in the legacy SI line. Note that a plain cylinder drifts on air loss; use an external rod lock or pilot check valve for load holding.
Airtac SI40 Standard Cylinder SI40X8 Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40X8 |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40X8 |
| Bore size | Ø40 mm |
| Stroke | 8 mm |
| Acting type | Double acting |
| Port size | G1/4 |
| Rod thread | M12×1.25 |
| Fluid | Air (filtered by 40µm element) |
|---|---|
| Operating pressure | 0.15 – 1.0 MPa |
| Proof pressure | 1.5 MPa |
| Temperature | -20 to +70 °C |
| Speed range | 30 – 800 mm/s |
| Cushion | Adjustable, 27 mm |
| Max standard stroke | Up to 1200 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI40X8 carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø40mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 628 N | 528 N |
| 0.7 MPa | 880 N | — |
| Max (@1.0 MPa) | 128 kgf | |
The SAI40X8 produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI40 Standard Cylinder SI40X8
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | Bore size in mm. |
| ×8 | Stroke length in mm. |
| -S | Optional built-in magnet for sensor position sensing. |
Legacy SI-family variants: SID (double rod), SIJ (adjustable stroke) — each maps to its SAI equivalent (SID→SAID, SIJ→SAIJ). Rod material: carbon steel (blank) / SUS420J2 (A) / SUS304 (B).
Where the Airtac SI40 Standard Cylinder SI40X8 Is Used
Short-Stroke Clamping
Ideal for holding light workpieces in machining fixtures where an 8 mm travel and 628 N force securely position parts without bulk.
Ejector Mechanism
Provides a fast 30-800 mm/s ejection pulse for small components, using the adjustable 27 mm air cushion to soften end-of-stroke impact.
Valve Actuation
Suitable for toggling diverter gates or small process valves, delivering reliable 528 N pull force within a compact ISO 15552 footprint.
Replacing the Airtac SI40 Standard Cylinder SI40X8 with the SAI40X8
To replace the discontinued SI40X8, order the SAI40X8. Verify the ISO 15552 mounting interface, 40 mm bore, 8 mm stroke, G1/4 port (PT/G/NPT thread options), and mounting accessory. Because this SKU lacks the -S magnet, it cannot take a sensor; the SAI family uses current AirTAC switches if sensing is needed. If you need more force, the neighbouring 50 mm bore yields 982 N push at 0.5 MPa; if less force is acceptable, the 32 mm bore provides 402 N. For load holding on air loss, remember the cushion only decelerates and does not lock the piston—consider the SAIL or BSAI lock variants, or an external pilot check valve.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40X8
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI40 Standard Cylinder SI40X8 FAQ
Yes, the SI40X8 is discontinued. The direct replacement is the SAI40X8. It is dimensionally interchangeable per ISO 15552, retaining the same 40 mm bore, 8 mm stroke, G1/4 port, and mounting interface to fit existing fixtures perfectly.
This 40 mm bore cylinder features a G1/4 air port and an M12x1.25 rod thread. The thrust is 628 N push and 528 N pull at 0.5 MPa, 879 N push at 0.7 MPa, 1130 N push at 0.9 MPa, with a theoretical max of 128 kgf at 1.0 MPa.
Request a Quote for the SAI40X8
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40X8 replacement — usually within 7-8 hours.