JFK ball recirculating bushings
JFK linear ball bushings
- High precision and rigidity
- Closed, open, and adjustable versions
JFK ball recirculating bushings, also known as ball recirculating bearings, consist of a cylindrical steel outer ring with a special heat treatment, a ball-retaining cage (made of stamped steel or polyamide), and two end rings that retain the cages. The components are assembled to optimize the function of each individual part. They operate at temperatures ranging from -20°C to +110°C.
JFK Group offers ball recirculating bushings (or ball bushings) in closed (KB), open (KB_O), and adjustable (KB_J) versions, as well as KH ball bushings for short travel applications with minimal space requirements. Ball recirculating bushings are dimensionally interchangeable and can withstand loads acting in any direction.
For proper operation, ball recirculating bushings require hardened and ground shafts, lubricated with turbine oil or lithium grease. The shaft/bushing and housing/bushing fits must be specified so as not to affect the operation of the linear system.
Versions
Four versions: how to choose the right ball bushing
The choice depends on the type of housing, whether play adjustment is required, and the available space constraints.
Closed ball recirculating bushings - KB Series
Closed version · Dimensionally interchangeable · Loads in any directionStandard closed version. Cylindrical outer ring with heat treatment for increased hardness and long service life. Cage made of stamped steel or polyamide. Suitable for the vast majority of linear motion applications on hardened cylindrical shafts. Dimensionally interchangeable with BA plain bushings.
Open ball recirculating bushings - KB_O Series
Open version · Lateral shaft access · Dimensionally interchangeable with BAOOpen version for housings with a longitudinal opening. Same design features as the KB Series, with an opening in the outer ring. Suitable for applications requiring lateral access to the shaft. Dimensionally interchangeable with BAO plain bushings.
Adjustable ball recirculating bushings - KB_J Series
Adjustable play · Wear compensation · Optimised precisionAdjustable version for play compensation. Allows fine adjustment of radial play, optimizing motion accuracy according to operating conditions.
Ball bushings - KH Series
Limited travel · Compact design · Maintenance-freeDrawn hardened steel sheet housing, synthetic resin cage, and precision balls. Designed for non-rotating linear motion with short travel. Minimal space requirements, maintenance-free operation, and cost efficiency. Dimensionally interchangeable with BAL plain bushings.
Performances
Design and performance features
Steel outer ring with dedicated heat treatment for hardness, rigidity, and long service life.
Outer ring made of steel with a specialised heat treatment
The steel outer ring with special heat treatment provides the required hardness for long service life, both in terms of travel distance and operating hours.
Loads acting in any direction
The design allows the bushing to withstand loads acting in any direction, ensuring versatility across different mounting configurations.
Simple and interchangeable
Easy installation and interchangeability — including with BA/BAO/BAL Series plain bushings — simplify both installation and replacement.
Turbine oil or lithium grease
They require lubrication with turbine oil or lithium grease. Felt rings used as additional seals improve lubricant retention and extend relubrication intervals.
Mounting
Ball recirculating bushing installation
Avoid dropping or impacting the components. Check the dimensions of the housing, shaft, and mounting surface before installation. Thoroughly clean the mounting surfaces, as foreign matter can cause damage to the system. Excessive adjustment and the resulting deformation of the outer ring negatively affect motion accuracy and service life. The shaft/bushing and housing/bushing fits must be specified so as not to interfere with the proper operation of the linear system.
Mounting methods
- Inspection and cleaning of surfacesCheck the dimensions of the housing, shaft, and mounting surface before installation. Thoroughly clean the mounting surfaces, as foreign matter can cause damage to the system.
- Handling and adjustmentAvoid dropping or impacting the components during handling. Excessive adjustment and the resulting deformation of the outer ring negatively affect motion accuracy and service life. The shaft/bushing and housing/bushing fits must be specified so as not to interfere with the proper operation of the linear system.
Technical data
- Operating temperature
- –20°C / +110°C
- Required shaft
- Hardened and ground
Applications
Applications
Components and application support for every industrial environment.
Machine tools and CNC
Linear axes requiring high precision on hardened cylindrical shafts. Ball recirculating bushings are the standard solution for applications with high precision requirements.Industrial automation
Linear actuators and motion systems with continuous operating cycles. Long service life and easy replacement help reduce machine downtime.
Robotics
Linear robot axes requiring high precision and repeatability. Dimensional interchangeability simplifies maintenance.
Packaging machinery
Fast and precise linear motion in environments with potential contaminants. Integrated seals protect the system from dust and foreign particles.Technical documents
Contacts
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