This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125AX425, 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 SI125AX425
The AirTAC SI125 Standard Cylinder SI125AX425 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 SAI125AX425, 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 → SAI125AX425
- 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 SI125AX425
The AirTAC SI125AX425 is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 425 mm stroke. It delivers 6136 N push force at 0.5 MPa and features a G1/2 port, M27x2 rod thread, and SUS420J2 stainless steel rod. The direct replacement is the SAI125AX425, matching the exact ISO 15552 mounting interface, bore, stroke, force, and port.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. Because this SKU lacks a magnet (-S), it cannot accept a CS1-B/DS1-B sensor.
Airtac SI125 Standard Cylinder SI125AX425 Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125AX425 |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125AX425 |
| 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 SAI125AX425 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 SAI125AX425 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 SI125AX425
| 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 SI125AX425 Is Used
Heavy-Duty Pressing
Applies 6136 N of thrust at 0.5 MPa for seating large bearings and forming heavy gauge components in automated machinery.
Large Fixture Clamping
Secures oversized weldments or castings during machining, relying on the robust 32 mm SUS420J2 stainless rod to resist corrosion and deflection.
Replacing the Airtac SI125 Standard Cylinder SI125AX425 with the SAI125AX425
To replace the SI125AX425, order the SAI125AX425 and confirm the ISO 15552 mounting accessory (LB, FA, TC, etc.), the G1/2 port, and the 425 mm stroke. This SKU has no magnet, so position sensing is impossible without changing the rod assembly. If you need load holding on air loss, a plain cylinder drifts; use an external rod lock, pilot check valve, or the SAIL/BSAI lock variants. For sizing both ways, the neighboring 100 mm bore yields 3927 N push at 0.5 MPa, while the 160 mm bore yields 10053 N. At 425 mm stroke, prevent rod bending by using an external guide to absorb side loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125AX425
- ✓ 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 SI125AX425 FAQ
Yes, the SI125AX425 is discontinued. The direct replacement is the SAI125AX425, which shares the identical ISO 15552 mounting interface, 125 mm bore, 425 mm stroke, output force, and G1/2 port.
It features a G1/2 port and delivers 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 max of 1251 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125AX425
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125AX425 replacement — usually within 7-8 hours.