This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40X638S, 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 SI40X638S
The AirTAC Airtac SI40 Standard Cylinder SI40X638S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 638mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40X638S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke638 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40X638S
- 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 SI40X638S
The AirTAC SI40X638S is a discontinued double-acting ISO 15552 profile cylinder with a 40 mm bore and 638 mm stroke. It delivers 628 N push force at 0.5 MPa through a G1/4 port. AirTAC replaced this legacy unit with the SAI40X638S, a direct sharing the exact interface, bore, stroke, force and mounting.
The SAI upgrade features a two Y-shaped one-way piston seal for low start-up pressure and long life. It also adds SAIL, SAIF and BSAI variants the SI lacked. The -S suffix means a piston magnet for CS1-B/DS1-B switches.
Airtac SI40 Standard Cylinder SI40X638S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40X638S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40X638S |
| Bore size | Ø40 mm |
| Stroke | 638 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 SAI40X638S 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 SAI40X638S 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 SI40X638S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | Bore size in mm. |
| ×638 | 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 SI40X638S Is Used
Carton Diverting
Pushes packages at 90 degrees on sorting lines using the 628 N push force, with the long 638 mm stroke reaching across wide conveyor belts.
Pallet Push-Off
Acts as a sweep arm to push goods off pallets, where the 32 kg vertical lift capacity and extended stroke handle moderate loads over distance.
Light Pressing
Provides downward clamping pressure for light assembly tasks, benefiting from the adjustable 27 mm air cushions to decelerate the rod at stroke end.
Replacing the Airtac SI40 Standard Cylinder SI40X638S with the SAI40X638S
To replace the SI40X638S, order the SAI40X638S. Confirm the ISO 15552 mounting interface, 40 mm bore, 638 mm stroke, G1/4 port (PT/G/NPT) and mounting accessory. The -S magnet enables current AirTAC switches (legacy used CS1-B/DS1-B). Sizing both ways: a 32 mm bore yields 402 N push at 0.5 MPa, while a 50 mm bore yields 982 N. A plain cylinder drifts on air loss; the cushion only decelerates. For load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant. At 638 mm, prevent rod bending by guiding the load externally to avoid side-load damage.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40X638S
- ✓ 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 SI40X638S FAQ
Yes, the SI40X638S is discontinued. The direct replacement is the SAI40X638S. It shares the same ISO 15552 mounting interface, 40 mm bore, 638 mm stroke, output force, G1/4 port and accessories, fitting existing fixtures perfectly.
This double-acting cylinder operates at 30-800 mm/s. Force outputs are: 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, and a theoretical max of 128 kgf at 1.0 MPa. It features a G1/4 port and M12x1.25 rod thread.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40X638S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40X638S replacement — usually within 7-8 hours.