Reducing Motor Bearing Failures: Modified Lubrication Procedures Improve Reliability at TVA

The result of their failure can be unexpected downtime, higher maintenance costs or even personnel safety risks. In the worst cases, human lives may be at stake. It is time to stop treating grease as some simple substance that just needs to be pumped into machines at some random frequency and then hoping for the best. Machine greasing must be a systematic and carefully planned process to ensure safe operation of assets and to achieve maximum equipment life.

Proper lubrication is an essential maintenance function and changing oil is one aspect of the process. Unlike changing the oil in your car based upon time or miles, oil changes for industrial equipment should be based on need where no other practical solution to restore proper lubrication is available. Too often, we schedule an oil change to rectify a contamination problem or when excessive wear is detected. In neither case is the oil change a certain correction of the root cause of the problem, and it wastes good money and further stresses the environment with hazardous waste.

The manufacturer using the bearing in his equipment, not the ball bearing manufacturer, determines the anticipated life of a ball bearing. This life, once determined, is called the L10 life of the bearing and it is based on the premise that 90% of the bearings will last a certain amount of revolutions before they experience metal fatigue.

Like all industry these days, the economics of running a plant requires a keen eye on operating costs. In an effort to increase uptime and reduce maintenance costs, the mechanical maintenance team at the Valiant plant undertook a program to reduce dryer bearing failures with lubrication management, which included aggressive contamination control and oil analysis.

Ultrasonic technology (UT) has become widely accepted for the detection of leaks in both pressurized and nonpressurized systems. Most compressor service companies and several manufacturers own some type of ultrasonic sensor for pinpointing leaks. It is easy to cost-justify the purchase of an ultrasonic sensor based upon the high cost of energy loss due to leaks. However, there is another application for ultrasound that consumers, nondestructive testing (NDT) organizations, and even developers and manufacturers of ultrasonic sensors are often not aware of or overlook. UT can be used as a means to detect early wear of components such as bearings and gears due to lack of lubrication or overlubrication.

There are different thoughts of what constitutes a "world class lubrication program." It is our belief that a world class lubrication program consists of researching, documenting and implementing the best lubrication practices and regulatory requirements as defined by the leaders in the lubrication and reliability industry (Noria, SMRP, ICML, etc.) as well as regulatory agencies (OSHA, EPA). We have determined that for most programs, best practices can be summarized into the following categories: