The great majority of bearings used on Formtek equipment are the anti‐friction type, i.e., ball or roller. A relatively small number are the plain sleeve type. Practically without exception, grease is employed for bearing lubrication.
The lubricant must serve two purposes in the operation of anti‐friction bearings:
To prevent wear and tear of the highly-polished surfaces that promote bearing efficiency, the lubricant must counter any sliding that occurs. Rust protection is vital, too, and a protective film essential.
Grease, applied with a pressure gun, is the widely accepted lubricant for anti‐friction bearings. Exceptions are bearings on gear or chain drives which receive oil by splash or circulation.
For best results, the grease used should be made specifically for service in anti‐friction bearings. Inferior or unsuitable grades are a prime source of premature bearing failure.
With bearings, rotative speed of the balls or rollers is several times that of the shaft which the bearing supports. Severe centrifugal effects and churning can result that separates the grease into its two principal components of oil and soap. For this reason, the grease employed should be a structurally stable product highly resistant to separation and caking -- in other words have good chemical stability.
In addition, proper greasing technique is needed to ensure effective protection of anti‐friction bearings. Where bearings are not equipped with seals, and clearances permit excess grease to escape, the housing should be pumped full of grease until some of the new lubricant shows at the bearing ends. This practice provides a beneficial flushing action and helps to seal the bearing against penetration of dirt or impurities.
In the case of sealed anti‐friction bearings, a completely different technique is desirable. The grease does not have an opportunity to escape and re‐lubrication is required only at long intervals, typically every three months.
Finally, plain sleeve bearings. In this case, the grease can readily escape at bearing ends. Consequently, relatively frequent greasing, demonstrating good adhesive characteristics, is required so as to provide staying power and avoid the bearings running dry. Moreover, the bearings should be completely filled when the grease gun is applied, creating a flushing action which helps to seal out grit and impurities.