Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1061099
is critical, or you are just looking to opti- mize operating costs, the following steps are important for trouble-free grease lubrication: 1. Choose the Right Grease "Grease is just grease." The death of many machines begins with this statement of ignorance. is perception is not helped by oversimplifi ed instructions from original equipment manufacturers. "Use a good grade of No. 2 grease" is the extent of guidance given for some equipment. However, if long, trouble- free asset life is the goal, then the selec- tion of grease must include the proper base oil viscosity, base oil type, thickener type, NLGI grade and additive package. 2. Determine Where and How to Apply Some machine locations have a prominent Zerk fi tting, and the choice of where and how to apply grease seems obvious. But is there just one fi tting? My dad is a farmer, and when he purchases a new implement, his fi rst action is to review the manual or survey all parts of the machine to determine the number of greasing points. He then creates his "lubrica- tion procedure," which consists of writing the total number of fi ttings and hints on where the tricky ones are hidden with a permanent marker on the machine. In other cases, the application point may not be obvious or may require special tools for proper application. For threaded applications, like the jackscrew mentioned previously, achieving suffi cient coverage of the threads can be challenging. Tools exist to help ensure complete coverage of valve stem threads, for example, which can make a big diff erence. 3. Select the Optimal Frequency Unfor tu nately, ma ny ma intena nce programs decide on the grease lubrication frequency out of convenience. Rather than consider the conditions of each machine and how quickly a specifi c grease will degrade or be contaminated, some generic frequency is selected and applied equally to all. Perhaps a route is created to grease all machines once per quarter or once per month, and a few shots of grease are applied at each point. However, "one size fi ts all" rarely fi ts any optimally. Tables and calculations exist for identifying the correct frequency based on speed and temperature, and adjustments can be made according to estimates of contaminant levels and other factors. Taking the time to establish and then follow a proper lubrication interval will improve machine life. 4. Monitor for Lubrication Eff ectiveness Once the right grease has been selected and an optimized relubrication schedule developed, it is still necessary to evaluate and adjust as needed due to diff erences in fi eld conditions. One way to test lubrication eff ectiveness is with the use of ultrasonic monitoring. By listening for sounds gener- ated by asperity contact in ineff ective bearing lubrication and determining the amount of grease required to restore the bearing to the correct lubricated condition, you can make adjustments to the calculated values and achieve precision lubrication. 5. Use the Proper Method for Grease Sampling In addition to the use of ultrasonic moni- toring, feedback on greasing eff ectiveness can be obtained through grease analysis, but fi rst a representative sample must be taken. New tools and techniques for grease sampling have recently been developed. Although grease analysis doesn't happen as often as oil anal- ysis, it can prove benefi cial in monitoring the equipment condition, lubricant condition and lubricant life. 6. Choose the Appropriate Test Slate Maximum equipment life can be achieved by ensuring grease lubrication is eff ective. is also results in minimal wear. Detection of wear quantities and modes can help you make adjustments and discover problems earlier. It is important to monitor in-service grease consis- tency, as grease that softens too much can run out of the machine or fail to stay in place. Grease that hardens can provide inadequate lubrication and increase the load and electrical consumption. Grease mixing with the wrong product is one of the most common causes of failure. Early detection of this condition can allow purging and restoration before signifi - cant damage takes place. Tests to measure the quantity of moisture and particle counts in grease have been developed. Utilizing them to identify contaminant ingression, or just plain dirty greases, can present the opportunity for life extension through the use of clean greases and more eff ective sealing mechanisms. 7. Implement Lessons Learned While even a single bearing failure is regrettable, it is worse still when the opportu- nity to learn from it is squandered. I'm often told there is "no time" to save bearings and document as-found conditions following a failure. e focus is on restoring production. Broken parts are thrown away or put in the parts washer where the evidence of the failure is washed away. If a failed part and the grease can be recovered from the ocean fl oor, you should be able to save these components following a plant failure. Understanding the reasons a failure occurred doesn't just impact the restoration of the machine but can have a multiplied eff ect on the reliability and life of other components across the enterprise. Ensure that root cause failure analysis includes inspection of the bearing surfaces, but fi rst start with pres- ervation and then removal of the grease for analysis. Combining results from the lubricant analysis with the bearing analysis will create a more comprehensive picture of the failure and help you determine which corrective actions can be used to prevent it from happening in the future. ML ML www . machinerylubrication.com | November - December 2018 | 25 35% of lubrication professionals never inspect the grease discharge from bearings and other machine components at their plant, based on a recent survey at MachineryLubrication.com