Ball Bearing Tips
By Dale Hamil
Technical Education Committee Member
Illinois Electric Works
Granite City, lllinois
Hamil, D. (2023). Ball Bearing Tips. EASA Currents, 10.
Extending bearing life is the subject of hundreds of articles. Most have to do with lubrication do's and don'ts, mounting issues, improper handling and contamination. This article is not intended to supplant any of those articles. My intent here is to provide some common sense guidance and provide links to resources that can help.
First things first - Rule number one is to buy anti-friction bearings from a known and traceable source. Everyone seems to have their favorite bearing manufacturer, but the truth is that all the major bearing manufacturers make quality products. Be aware that third world and counterfeit bearings are out there. Two ready resources that can provide guidance to identify fake or fraudulent bearings are stopfakebearlngs.com and go.easa.com/hacb.
Rule number two is to measure bearing fits with confidence. A best practice is to use dial bore gauges and calibrated rings to measure bores or calibrated micrometers. Check calibration before every use. Use good measurement techniques and be aware of any temperature differences in the standard, micrometer and part.
Bearing lubrication is beyond the scope of this article; however, Exxon-Mobil PolyrexEM has become the most frequently cited universal standard for typical applications. Roller bearings or conditions may benefit from different lubricants. Take a minute to subscribe to Machinery Lubrication magazine. There's a lot of best practices there. You can find it at machlnerylubrlcatlon.com/page/subscrlptlons.
Bearings need to be stored in a temperature-controlled and contamination-free environment, free from ambient and seismic vibration. Lining the shelves with soft rubber will help prevent brinelling of the races. Using rubber that compresses to about 2/3 the thickness is a good rule of thumb.
During the rebuilding process, grease paths should be scrupulously cleaned and then the lines recharged with good lubricant. Place a plastic cap on the Zirk fitting if so equipped.
Application of an aftermarket labyrinth seal designed for that purpose is a great way to improve on the original design and boost your bottom line at the same time. Restore all the running clearance seal fits to the EASA AR100 standard.
For higher speed applications, consider using ceramic hybrid bearings. The limiting speeds of ceramic hybrid bearings are considerably higher than conventional steel ball bearings with the added value of mitigating electrical discharges. Those bearings require less lubrication according to the manufacturers.
Speaking of electrical discharges, there are a number of methods to mitigate those as well. Bearings coated on the outer race are common as well as insulated shafts or housings. Providing an electrical path to ground with micro-fiber brushes or conventional grounding brushes are well known methods to reroute the offending current.
