Why is bearing so important?

Bearing has two major functions.

Function 1

Reduce friction and make rotation smoother. There will definitely be friction between the rotating "shaft" and the rotating support part. Bearings are used between the rotating "shaft" and the rotating support part. Bearings reduce friction, allowing for smoother rotation and reduced energy consumption. This is what bearings do.

Function 2

Protects the rotation support part and keeps the rotation "axis" in the correct position. There will be a lot of force between the rotating "axis" and the rotating support part. Bearings prevent the rotating support parts from being damaged by this force, keeping the rotating "axle" in the correct position. It is precisely because of these functions of bearings that we can use the machine repeatedly for a long time.