Up Time Magazine- August/September 2008

verity of the bearing fault. It can also be used in a similar way to the enveloping technique, which provides a spectrum and waveform for detailed analysis. Spike Energy™ – Developed by the IRD Mechanalysis company (bought by Entek, then by Rockwell) in the 1970’s, the Spike Energy method utilizes the mounted resonance of the accelerometer in a similar way to the Figure 3 – The Effects of Enveloping/Demodulation Shock Pulse Method. The vibration on the signal. from the sensor (filtered around the resonant frequency) goes through a Figure 3, the time between each “spike” is the process that holds the peak levels so that a gSE time that it takes for each rolling element to roll reading can be trended. In addition, a spectrum over the damaged area on the outer race – it reand time waveform can be displayed in a similar lates to the ball pass outer frequency (BPFO) – as way to classical enveloping. It is very important shown in Figure 1. It is essential to set the high that the same sensor is used for each measure- pass filter correctly so that the vibration that rement, because a different sensor will produce dif- mains only comes from the bearing (and not from ferent amplitude readings. the gearbox, for example). Enveloping and Demodulation – These two names are used to essentially describe the same process. The process is used to perform two functions: remove the high amplitude, low frequency vibration (which would otherwise swamp the low amplitude bearing vibration), and convert the high frequency “spikes” into a low frequency signal so that waveform and spectrum analysis can be performed. In The envelope spectrum will contain noise if there are no faults, and peaks (and harmonics) at the bearing forcing frequencies if there is a fault. The amplitude of these peaks will increase as the fault develops, and the noise floor will lift and swallow the peaks when the bearing is in the last stage of bearing failure. Figure 2 – Using Airborne Ultrasound to check bearings. to avoid under- or over-greasing, as long as it is done with great care. Shock Pulse Method: SPM® – The SPM company developed a vibration sensor in the 1960’s that will resonate in a predictable way at approximately 30 kHz. When there is inadequate lubrication, and in the earliest stage of a bearing failure, the sensor will resonate. The “carpet” level of the vibration is monitored, as are the peaks, or “spikes” that occur due metal-to-metal contact. If the sensor is mounted correctly, the Shock Pulse Method, also used by the PRÜFTECHNIK company, can indicate the nature of the lubrication problem and the se- AFTER SETTING RECORD ATTENDANCE in 2007 with over 1,000 people, this year’s Annual Conference is sure to be the best yet. Session Tracks From the Five Pillars of the SMRP Body of Knowledge SMRP Initiatives Track Educational Workshops Exciting Keynote Speaker Comedic Entertainment Plant Tours Networking at the Rock-N-Roll Hall of Fame Golf Tournament DON’T MISS YOUR CHANCE TO ROCK OUT LARGEST AT THE YEAR’S MAINTENANCE & RELIABILITY EVENT. EXHIBITOR AND SPONSOR OPPORTUNITIES STILL AVAILABLE! REGISTER EARLY AND RECEIVE EARLY BIRD DISCOUNT Rock-n-Bowl Reception IT’S ALL TAKING PLACE OCTOBER 20-23, 2008 IN CLEVELAND, OH 64 august/september 2008

Table of Contents Feed for the Digital Edition of Up Time Magazine- August/September 2008

Up Time Magazine- August/September 2008 Contents Upfront Upclose Information Technology Lubrication Infrared Maintenance Management Motor Testing Precision Maintenance Reliability Ultrasound Vibration Upgrade

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