1. Geometric Configuration: Flange Mounting
The defining characteristic of the FK/FF Series is the round mounting flange, specifically engineered to solve integration challenges in wall-mounted applications.
The Challenge: Many machine designs (such as Z-axis towers or enclosed actuators) lack a horizontal base for standard pillow blocks, necessitating the screw to pass through structural walls or plates.
The Solution: FK/FF units are designed to bolt parallel to the screw axis. The FK (Fixed) unit mounts directly to the motor-side wall, while the FF (Floating) unit mounts to the distal end-plate.
Structural Advantage: This direct mounting capability eliminates the need for L-brackets or standoffs, effectively reducing the lever arm moment and significantly increasing system stiffness.
2. FK Series: The Fixed Anchor
The FK unit functions as the primary rigid anchor, designed to maintain axial positioning accuracy.
Bearing Configuration (DF): The housing contains a pair of Angular Contact Ball Bearings (typically JIS 70-series) arranged in a "Face-to-Face" (DF) configuration. This setup absorbs heavy bidirectional thrust loads while providing self-alignment to compensate for minor machining deviations in the mounting surface.
Preload: A precision lock nut applies preload to the bearings, eliminating internal clearance. This ensures zero backlash at the support point during direction reversals.
Protection: Integrated oil seals retain lubrication and prevent contamination, ensuring the longevity of the precision bearings.
3. FF Series: The Floating Support
The FF unit acts as the passive support, engineered specifically for thermal compensation.
Internal Component: It features a single Deep Groove Ball Bearing.
The Floating Principle: While the bearing is secured to the screw shaft via a snap ring, it is not axially clamped within the housing.
Thermal Management: During operation, friction generates heat, causing the steel ball screw to elongate. If the tail end were rigidly fixed, this expansion would cause the screw to buckle and vibrate. The FF unit supports the radial weight of the screw while allowing the bearing to slide axially within the housing, accommodating thermal growth without stress.