Working of cylindrical ball spline

Structure and Working Principle
Basic components:
Shaft: A cylindrical shaft with precision spiral or linear grooves machined on its surface.
Nut/Sleeve: A cylindrical component that is fitted onto a shaft and has a ball circulation track embedded inside.
Balls: Rolling between the shaft and sleeve to achieve low friction motion.
Retainers and seals: Ensure smooth ball circulation and prevent dust from entering.
Working Principle:
The ball rotates in the groove between the spline shaft and the sleeve, transmitting torque (rotational motion) and sliding along the axial direction (linear motion).
Pre compression design can eliminate gaps, improve rigidity and positioning accuracy.
Main Features
Composite athletic ability:
Simultaneously supporting rotation and linear motion, reducing the number of components and simplifying structural design.
High precision and high rigidity:
The precision ball circulation system ensures low friction and high positioning accuracy (micrometer level).
Pre compression design enhances rigidity and is suitable for heavy-duty or high-speed scenarios.
Long lifespan and low maintenance:
Ball contact reduces wear and extends service life with sealing design.
Compact design:
The cylindrical structure saves space and is suitable for equipment with narrow or complex layouts.
Typical application scenarios
Industrial robot:
At the joints of the robotic arm, a composite action of rotation and linear motion is achieved.
Semiconductor equipment:
High precision positioning of wafer handling robotic arm.
numerical control machine:
Tool feed system ensures high-speed and high-precision machining.
automatic production line:
Conveyor belt indexing mechanism or precision assembly equipment.
Selection and Precautions
Load capacity:
Axial load, radial load, and torque need to be calculated to select the appropriate size.
Travel and accuracy:
Select the axis length based on the distance of movement, and choose standard precision or ultra high precision models according to the requirements.
Installation method:
The configuration of the fixed end and the support end must comply with the equipment structure (such as flange installation or base fixation).
Environmental adaptability:
Special materials or sealing levels (such as IP67 protection) should be selected for high temperature, dusty or corrosive environments.
Difference from Linear Guides
Ball spline: allows axial sliding while transmitting rotational torque, suitable for composite motion scenarios.
Linear guide rail: only supports linear motion, does not transmit torque, and is usually used in conjunction with rotary drives (such as motors).
Maintenance points
Lubrication:
Regularly inject specialized lubricating grease (such as lithium based grease) to reduce ball wear.
Cleaning and dust prevention:
Use sealing rings or protective covers to prevent impurities from entering the raceway.
Check pre pressure:
After long-term use, it is necessary to check whether the preloading has failed to avoid a decrease in accuracy caused by gaps.