SCS25 Aluminum Shaft Collar – 25 mm Bore, 8 mm Keyway, High-Torque Drive Shaft Positioning
The SCS25 shaft collar introduces the 8 mm keyway — the widest key slot in the lower half of the SCS series — for a bore size that sits at the crossroads of precision automation and genuine industrial power transmission. A 25 mm shaft is the standard output for industrial servo motors in the 750 W to 2.2 kW range, for heavy-duty ball-screw assemblies in machining centres, and for primary drive shafts of industrial robots in the 10–25 kg payload class.
The 8 mm keyway (DIN 6885A 8×7) can transmit significantly more torque than the 6 mm keyway of the SCS20–22 range. Combined with the retained 45 mm OD and 12 mm face width of the SCS22, the SCS25 delivers high torque-locking capability within a compact envelope.
Technical Specifications – SCS25
| Parameter | Value | Notes |
|---|---|---|
| Model | SCS25 | Single-split clamp type |
| Bore (d) | 25 mm | Fits Ø25 shafts |
| Outer Diameter (D) | 45 mm | Wall thickness 10.0 mm per side |
| Width (B) | 12 mm | Axial face width |
| Clamping Screw | M5 | Countersunk socket-head cap screw |
| Slit Width (W) | 1.5 mm | Opening gap for shaft insertion |
| Keyway (K) | 8 | Standard; custom keyway on request |
| Material | Aluminium alloy | ~2.7 g/cm³, corrosion resistant |
Design Features and Performance Advantages
⚡ 8mm Keyway: 75% More Torque Capacity
Versus 6mm keyway — handles multi-kilowatt servo drive torques without key rocking or keyway wall fatigue.
🏗 Precision Ground Face Option
Available with face flatness tolerance for ball-screw thrust-bearing datum applications in machine tool builds.
📈 25mm Universal Servo Standard
25mm shaft covers 750W–2.2kW servo motors and heavy-duty ball-screws — the power band where reliability matters most.
⚙ Shared 45mm OD with SCS22
Use one housing bore for 22mm and 25mm shaft variants — reduce drawing and tooling complexity in modular machine designs.
Application Sectors
▶ High-Dynamic Servo Drive Ball-Screw Retention
25 mm is a standard ball-screw journal diameter for precision machining centres and semiconductor handling equipment. An SCS25 at the fixed bearing end provides the axial datum for the angular contact bearing preload, maintaining the screw's positional stiffness across the full operating temperature range.
▶ Industrial Robot Primary Drive Shafts
Shoulder and elbow joints of industrial robots in the 10–25 kg payload class run primary axis reduction gear outputs on 25 mm shafts. The SCS25 with 8 mm keyway locks the arm link to the shaft both axially and rotationally — dual retention required in joints experiencing both axial gravity loading and full torque reversals.
▶ Heavy-Duty Spindle and Milling Head Positioning
Milling and boring head spindles in machining centres use 25 mm tool arbour retention shafts. An SCS25 defines the axial position of the tool arbour retention nut torque datum, ensuring consistent tool pull-out force across tool changes.
Installation and Mounting Notes
At 25 mm bore with 45 mm OD, the wall thickness of 10 mm per side is maintained despite the bore growing by 3 mm versus the SCS22 — achieved by the 8 mm keyway being accommodated within the existing wall section. A particularly effective use of the SCS25 is as a precision-ground face collar on a ball-screw end journal bearing, where the collar face serves as the thrust-bearing datum surface for the ball-screw preload. Contact EP to discuss precision-ground face options.
Frequently Asked Questions – SCS25
How much more torque can an 8mm keyway transmit compared to a 6mm keyway?
Moving from 6×6 to 8×7 (DIN 6885A) on a 25 mm shaft increases the theoretical shear area by approximately 75%, assuming the same material and key length. Actual torque ratings depend on key length and fit tolerance — contact EP for a specific application calculation.
Is the SCS25 compatible with angular contact bearings used in ball-screw fixed-end support?
Yes. The SCS25 is commonly used in conjunction with paired angular contact bearings at the fixed end of a ball-screw assembly. The collar face provides the axial datum against which the outer bearing ring is preloaded. Confirm face runout (typically
Can the SCS25 be ordered with a tighter bore tolerance than standard?
Yes. Custom bore tolerances (H6, H5, or as specified) are available for precision-positioning applications. Submit your technical drawing via the EP contacts page.
What is the MOQ for the SCS25 with keyway?
MOQ is 100 pieces for both keyway and non-keyway variants. Keyway machining is performed as part of the same production run — no additional MOQ applies.
Specify SCS25 for High-Torque Servo Drive Assemblies
MOQ 100 pcs | 8mm keyway for max torque | Precision-ground face option available