Ball splines are used to provide low or no friction linear motion where a high degree of accuracy or high operating speed is required. Ball bearings run along tracks cut along the axis of the shaft and the inner of the cylinder, and are held in place by a cage or retainer. The running length of the track can be of a variety of lengths, which is known as the ‘stroke’. There are different versions for different lengths of stroke.

Benefits of BNL plastic ball splines and ball spline cages are:

  • A cost-effective alternative to machined versions
  • Quicker, high-volume production with consistent quality via moulding
  • No need for extra ops to remove the plastic after inaccurate milling
  • Moulding uses less plastic for a lighter, better value product
  • Thinner wall sections can be achieved than in machining
  • Chemical and corrosion resistance vs metal versions
  • Reduced friction and heat for less wear and longer operational life
  • Less noise, vibration and harshness (NVH) in the system



BNL offer our customers ball spline cages, also known as retainers, or custom ball spline functionality designed for your specific shaft application. Our bespoke, injection-moulded ball spline cages are used in short-stroke ball splines to provide accurate, fast linear adjustment.

We use the same circular profile in our ball spline cages as we do in our bearings, providing single point contact that minimises heat and friction, resulting in reduced wear and longer operational life. Moulding products is more cost-effective and consistent for high volumes, so we can offer value without sacrificing quality.

We can also integrate a ball spline cage with other features or mating parts to reduce component count and cost. We can offer bespoke variations on a standard design or integrate components into one moulded part.


Ball Spline Materials

Our cages are usually available in POM but we can offer other materials dependent on the requirements of the application, such as Nylon use for higher temperatures. We can work with different options of ball size, material and configuration. We use Chrome Molybdenum balls as standard as they are very hard wearing so have a better operating life, especially as most ball spline products will run on a steel cylinder. Grease is only needed in the case of an application which is frequently static as the Chrome Molybdenum balls will clean and corrosion from the track surface during operation, due to the relative hardness of the metal.

We are happy to take any special requests for specific materials or blends.

Ball Spline Applications

Ball splines are found in any application that requires high speed movement of components with and near zero axial friction.

  • Honing machines
  • Robotics
  • Automation
  • Control knobs
  • Oil, Gas, Water industry drills
  • Automotive Vehicle ball spline half shafts
  • Linear bearings

Do you think a plastic ball spline product or cage might bring advantages to your product development? Our Machine Tear Down Team are ready to work with you to discover how our plastic bearings and ball splines could be used in your application.


What type of ball spline are you currently using? Is it overspecified?

We have found that many customers are using long-stroke, circulating ball splines for applications that only need a short stroke. In circulating ball splines, the balls run off the end of the track and are recirculated back around to keep movement in applications that need a very long stroke. They are more technologically complex and more expensive and can be over specified for many applications.

Are you using a circulating ball spline where a limited stroke ball spline would work? Could you use one of BNL’s cost-effective ball splines instead?

Ask one of our engineers about your application requirements and see if a better value better value ball spline cage is suitable: