Can you preload a deep groove ball bearing? (Unveiling the details of this technical knowledge)

The answer is yes: Deep groove ball bearings can be preloaded, and in many precision or high-speed applications, preloading is crucial for ensuring their proper function.
Simply put, "preloading" means applying a small force to the bearing beforehand, making the steel balls and raceways fit more tightly, eliminating the subtle play (clearance) that would otherwise exist.

1. Why preload deep groove ball bearings?

Eliminate play and improve accuracy: Bearings have a slight "looseness" when they leave the factory. Without preloading, the shaft will wobble slightly when rotating. Preloading makes the shaft rotate more stably and accurately.
Prevent the steel balls from "slipping": At extremely high speeds or under low load, the steel balls may not be "rolling" but rather "sliding" on the raceway. Preloading applies pressure, forcing them to roll properly and preventing wear on the raceway.
Reduce noise: With the steel balls no longer wobbling, the bearing runs more smoothly and quietly.
Increase rigidity: Just like tightening shoelaces makes your feet feel more secure, a preloaded bearing is less prone to deformation under load and provides better support.

2. How is this force applied?

Using springs (constant pressure preloading): This is the most common method. A wave spring or coil spring is placed on one side of the bearing, pushing against the outer ring. The advantage of this method is that the force is very stable; even if the parts expand or contract due to temperature changes, the spring automatically compensates.
Using nuts or shims (positional preloading): The inner and outer rings are squeezed together directly using a nut or a shim of the correct thickness. This method makes the bearing very "rigid" and capable of bearing heavier loads, but it requires high installation precision; overtightening can easily cause the bearing to overheat and seize.

3. What to pay attention to during preloading?

Avoid "excessive force": If the preloading force is too great, the friction inside the bearing will increase dramatically, quickly causing it to overheat, smoke, or even seize. It depends on the application: For things like household electric fans and small motors, spring preloading is usually sufficient; but for high-precision machine tool spindles, the preloading force needs to be calculated and controlled with great precision.