This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125AX425S, 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 SI125 Standard Cylinder SI125AX425S
The AirTAC SI125 Standard Cylinder SI125AX425S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 425mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125AX425S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke425 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125AX425S
- 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 SI125 Standard Cylinder SI125AX425S
The AirTAC SI125AX425S is a discontinued double-acting ISO 15552 profile cylinder featuring a 125 mm bore, 425 mm stroke, and a SUS420J2 stainless steel rod. It delivers 6136 N push force at 0.5 MPa via a G1/2 port. AirTAC replaced this legacy unit with the SAI125AX425S, a direct upgrade retaining the exact ISO 15552 mounting interface, bore, stroke, and output force.
The SAI replacement introduces an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. For applications needing load holding, the SAI family adds SAIL and BSAI lock variants the SI lacked.
Airtac SI125 Standard Cylinder SI125AX425S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125AX425S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125AX425S |
| Bore size | Ø125 mm |
| Stroke | 425 mm |
| Acting type | Double acting |
| Port size | G1/2 |
| Rod thread | M27×2.0 |
| 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 – 500 mm/s |
| Cushion | Adjustable, 40 mm |
| Max standard stroke | Up to 1500 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI125AX425S carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø125mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 6136 N | 5734 N |
| 0.7 MPa | 8590 N | — |
| Max (@1.0 MPa) | 1251 kgf | |
The SAI125AX425S produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI125 Standard Cylinder SI125AX425S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×425 | 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 SI125 Standard Cylinder SI125AX425S Is Used
Heavy Press Forming
Applies the 6136 N push force at 0.5 MPa to seat and form heavy metal components in automated stamping lines.
Pallet Positioning
Shifts loaded pallets laterally using the 313 kg vertical lift margin, relying on the 425 mm stroke to clear conveyor boundaries.
Mold Actuation
Drives large injection molds where the SUS420J2 stainless rod resists corrosion from ambient humidity and cooling sprays.
Replacing the Airtac SI125 Standard Cylinder SI125AX425S with the SAI125AX425S
To replace the SI125AX425S, order the SAI125AX425S. Confirm the ISO 15552 mounting interface, G1/2 port, M27x2 rod thread, and the -S magnet for legacy CS1-B/DS1-B sensors. The SAI accepts current AirTAC switches. If sizing down, a 100 mm bore yields 3927 N push at 0.5 MPa; sizing up to 160 mm provides 10053 N. Note that a plain cylinder drifts on air loss—the cushion only decelerates—so use an external rod lock or pilot check valve for holding. The 425 mm stroke requires external guides to prevent rod bending under side loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125AX425S
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI125 Standard Cylinder SI125AX425S FAQ
Yes, the SI125AX425S is discontinued. The direct replacement is the SAI125AX425S. It shares the same ISO 15552 mounting interface, 125 mm bore, 425 mm stroke, G1/2 port, and output force, fitting existing fixtures perfectly.
It uses a G1/2 port. Force output is 6136 N push and 5734 N pull at 0.5 MPa, 8590 N push at 0.7 MPa, 11045 N push at 0.9 MPa, and a theoretical maximum of 1251 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125AX425S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125AX425S replacement — usually within 7-8 hours.