Maintenance Technology September 2016 - 81

20 and then to play back those recorded sounds in spectrum analysis software. This will provide the inspector with the audible sound heard in the field during the inspection and a visual "image" or spectrum of the recorded ultrasound. This method helps reduce the subjectivity of relying only on changes in the decibel level and in the sound tone or quality "heard" by the inspector. How Ultrasound Produces Better Lubrication Practices Ultrasonic technology helps the lubrication technician take a large portion of the guesswork out of lubrication needs. Ultrasound is a localized signal, meaning when a sensing probe is applied to a bearing, it will not be affected by "crosstalk"; thus, it allows the technician to hear and monitor the condition of each individual bearing, much the same way medical ultrasound can detect exactly which artery is clogged or which vein is leaking. AS AN EXAMPLE OF ULTRASOUND'S EFFICACY, CONSIDER THE SCENARIO BELOW: A maintenance manager at a large firm reports thatsince adopting ultrasound technology and practicingultrasound-assisted condition-based monitoring he sees improvement. Rather than "running to put out the fire," his planthas gone from close to 30 rotating equipment failuresper year to zero in three years. But how doesultrasound work, exactly, vis-à-vis lubrication? The first step is establishing a baseline level and a sound sample. This is ideally done when moving through a route for the first time by comparing decibel levels and sound qualities of similar bearings. Once established, each bearing can be trended over time for any changes in either amplitude or sound quality, and anomalies can easily be identified. Ultrasonic technology helps the lubrication technician take a large portion of the guesswork out of lubrication needs. When the amplitude of a bearing exceeds eight decibels and there is no difference in the sound quality established at baseline, the bearing needs to be lubricated. To prevent potentially disastrous over-lubrication, the technician should apply the proper lubrication, a little at a time, until the decibel level drops. Many departments set up their condition-based lubrication programs by incorporating a two-stage approach: 1. The reliability inspector uses a relatively sophisticated ultrasound instrument to monitor and trend bearings. A report of bearings in need of lubrication is produced. 2. The lube tech then uses a specialized ultrasound instrument that alerts the tech when to stop adding grease. (These instruments can be affixed to a regular grease gun or worn in a holster.) To improve efficiencies, it's a good practice for the technician to note when the equipment was last greased and how much grease was used to calculate roughly how much lubrication is used per week. By using ultrasound to lubricate every time, the technician produces historical data that can be used as a guide from previous calculations, helping the department determine whether the lubrication schedule can be modified - possibly saving man-hours - and whether the manufacturer's suggested lubrication amount is accurate or if less/more is needed. SOLUTIONS AUGUST 2016 10127-4056 SMRP Solutions SE.indd 20 8/22/16 9:43 AM

Table of Contents for the Digital Edition of Maintenance Technology September 2016