What should be done to a shaft shoulder before bearing installation?

Before installing bearings on a shaft shoulder, it is essential that the shoulder is in optimal condition. Having no scratches or burrs ensures a smooth and accurate fit for the bearing, which is crucial for its proper functioning. Any imperfections such as scratches or burrs can lead to misalignment, increased friction, and premature wear of the bearing. These flaws may also disrupt the transfer of loads through the shaft and into the bearing, potentially causing failure during operation.

While painting may be used for protective purposes, it can interfere with the tight tolerances that bearings require. Polishing might improve surface finish, but it does not address the critical aspect of ensuring the absence of defects like scratches. Greasing is important for lubrication but should be applied correctly once the bearing is installed and not directly on the shoulder surface prior to installation. Thus, maintaining the shoulder's surface quality by ensuring it is free from any scratches or burrs is the most effective practice to ensure a successful bearing installation.