The internal structure of the ball screw nut is precise and complex, and the ball bears high loads and rolls precisely in its circulation channel (raceway, returner, return tube).
Damage to a single ball (fragmentation, indentation, severe wear) will accelerate the failure of the entire system. Replacing the ball seems simple, but it is actually a difficult operation comparable to precision surgery.
Core cognition: Why is it strongly not recommended to replace the ball yourself?
1.Precision matching: The original ball is strictly screened and matched in terms of material (usually bearing steel or ceramic), hardness, diameter tolerance (micron level), and roundness. Randomly replacing balls from different batches or sources may cause uneven loads, increased noise, and rapid wear due to slight differences, even if the nominal size is the same.
2.Complexity of the circulation system: The ball forms a closed circulation path in the nut through a precisely designed returner (or end cap/insert tube structure). The disassembly process can easily destroy the geometric accuracy of the return path, causing the ball to get stuck and the circulation to be poor.
3.Cage/isolator issues: Some designs (especially large leads) use cages to isolate the balls. Cages are very easy to deform or misalign during disassembly and become useless.
4.Risk of contamination: Even a tiny speck of dust entering the raceway or return channel can become a source of wear.
5.Loss of preload: After reinstalling the balls, it is almost impossible to accurately restore the original preload (the force required to eliminate axial clearance). Too much preload will result in high resistance and high heat; too little preload will result in poor accuracy and clearance.
6.Very low success rate: Without special tools and rich experience, the probability of successfully reinstalling all balls and ensuring smooth circulation is extremely low. Once the balls are scattered or the returner is damaged, the nut is basically scrapped.
Conclusion:
Unless all of the following conditions are met, please replace the entire nut directly or contact professional repair:
1.The nut itself is structurally intact (no damage to the raceway).
2.Have spare balls of the same batch and specifications provided by the original manufacturer (replace as a whole set).
3.Have a special removal/installation tool for this type of nut (usually purchased from the manufacturer).
4.Have a dust-free operating environment (at least better than ISO Class 8 cleanliness).
5.The operator is extremely experienced.