SKF
Super-Precision Double Direction Angular Contact Thrust Ball Bearings
SKF super-precision double direction angular contact thrust ball bearings (BTW series) consist of two thrust ball bearing sets integrated into a single unit, capable of carrying bidirectional axial loads with high stiffness and accuracy. They are designed for screw drives, live centres, rotary tables, and the axial location of machine tool spindles. The bearings have a 60° contact angle for maximum axial capacity and are manufactured to P5 or P4 tolerances. The one-piece design simplifies handling compared to matched sets and ensures equal preload distribution. SKF supplies these bearings preloaded and ready to install. Their high axial stiffness enables precise positioning and feed accuracy in ball screws and linear axes.
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Bidirectional Axial Support
One bearing carries thrust in both directions.
High Stiffness 60° Contact Angle
Resists axial tool forces with minimal deflection.
Preloaded, Ready to Mount
No shimming or adjustment required.
Compact Integration
Replaces two separate thrust bearings, saving space.
P4 Precision
Consistent positioning accuracy.
Lubrication Ready
Pre-greased or oil-lubricated versions available.
BTW Bearings in Ball Screw Support
Precision ball screws require very stiff axial support to maintain positional accuracy under cutting loads. A pair of BTW bearings or a single BTW unit provides the required axial rigidity and minimises lost motion, essential for high-precision CNC machines.
Selecting Preload for Thrust Bearings
Rigid preload in the BTW series is set at the factory to maximise stiffness while preventing contact overheating. Selecting the correct preload class (GA, GB, GC) depends on the screw diameter, speed, and required accuracy. SKF’s preload selection charts guide this choice.