MOSIONX ball-screw support units: fixed (BK/EK/FK) and supported (BF/EF/FF) ends, selection by shaft diameter, bearing match and mounting notes.
A ball-screw support unit holds the screw shaft at both ends and transmits the axial force into the machine frame. Together with the screw and the coupling it forms the feed axis; its rigidity directly affects positioning accuracy and backlash.
| Type | Code | Role |
|---|---|---|
| Fixed end | BK / EK / FK | Carries axial force, radial force and bending moment; use a zero-clearance / preloaded bearing, lock it reliably. |
| Supported end | BF / EF / FF | Gives radial location and rotation support, allowing slight axial thermal expansion. |
Support units are sized by the screw shaft diameter (e.g. BK-10 / BF-10 for ⌀10 mm). Match the bearing speed rating to the screw's top rpm, and keep the screw overhang as short as possible to limit deflection.
| Shaft ⌀ (mm) | Typical unit | Lock-nut thread |
|---|---|---|
| 10 | BK-10 + BF-10 | M10 (ref. torque ≈ 28 N·m) |
| 12 | BK-12 + BF-12 | M12 (ref. torque ≈ 28 N·m) |
| 15 | BK-15 + BF-15 | M15 (ref. torque ≈ 46 N·m) |
| 20 | BK-20 + BF-20 | M20 (ref. torque ≈ 95 N·m) |
| 25 | BK-25 + BF-25 | M25 (ref. torque ≈ 180 N·m) |
Torque values are general references for precision lock nuts — always follow the manufacturer's manual and tighten symmetrically, step-by-step.