Even high-grade linear guides and precision-ground ball screws can experience binding, increased friction, and premature wear if integrated with improper mounting hardware. Achieving smooth, repeatable linear motion requires synchronized alignment across the entire drivetrain.
A. The Fixed-Floating Mounting Principle (BK/BF & EK/EF)
Frictional heat generated during operation causes ball screws to undergo thermal elongation. A coordinated mounting architecture is necessary to manage this expansion:
- Fixed End (BK or EK Block): Positioned at the drive end. It houses a matched pair of preloaded angular contact bearings in a face-to-face (DF) configuration. Secured by a precision locknut, this unit absorbs axial thrust in both push and pull directions without axial play.
- Floating End (BF or EF Block): Positioned at the distal end. It contains a single deep groove ball bearing retained by a snap ring. The bearing floats axially within the housing bore, allowing the shaft to expand and contract freely to prevent shaft bowing or bearing binding.
- Geometry Selection: Specify BK/BF blocks for standard machine bed heights; choose EK/EF blocks when a compact vertical center height is required.
B. Center-Height Synchronization (DSG Nut Housings)
Mounting a cylindrical, flanged ball screw nut to a planar machine carriage requires an adapter bracket. DSG Series Housings provide precision-machined seats tailored for standard DIN 69051 Form B flanges. Critically, their machined base-to-centerline height aligns with standard linear guide blocks (e.g., pairing a DSG20H with BK15 supports and HG20 carriage blocks), maintaining strict parallelism between the screw and guide rails.
C. Coaxial Motor Mounting (DB Series Brackets)
When separate motor brackets and BK bearing blocks are mounted independently, slight angular or parallel offsets introduce cyclic bending stresses on the shaft coupling and motor bearings. DB Series Integrated Brackets combine the motor mounting flange and the fixed-side bearing seat into a single monolithic block machined in one continuous CNC setup. This maintains concentricity within 0.01 mm, significantly reducing rotational vibration and assembly labor.
D. Coupling Selection: Rigid vs. Flexible
- Rigid Clamping Couplings (GNC Series): Solid aluminum clamping bodies offering backlash-free motion and high torsional stiffness. These are recommended only when shafts are aligned via monolithic brackets (such as the DB Series) on precision-machined beds, as they accommodate virtually no shaft misalignment.
- Flexible Couplings (Disc / Bellows-Type): Recommended when components are mounted on separate brackets across standard fabrication tolerances. Disc couplings compensate for minor angular and parallel offsets while maintaining zero backlash.