RCM-2009 Reliability Centered Maintenance Managers' Forum - March 23-26 - Daytona Hilton Ocean Walk Village - Daytona Beach Florida Join or Manage Your Profile Posting Boards Machinery Condition Monitoring and Predictive Maintenance Posts About Ultrasound Testing Frequency for Ue lube detection
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We just purchased a new SDT 170MD for our lubrication department. I have been assigned the task of learning the system and then training the lubricators on the finer points of Ultrasonic Lubrication.
Here's my problem...I cannot see (or hear) a change...any change...while greasing bearings. I wonder if the default frequency of 38.4 is not correct for this application. What is the frequency of choice for bearing lubrication??? Thanks in advance, Paul... |
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Paul,
I use and prefer the older SDT 150, and I have had no problem detecting a change in ultrasound level when greasing bearings. I assume that you are using the appropriate sensor and meter settings. You may want to verify that with SDT N. America. Here are a few instances when the UT level doesn't change when greasing: 1) the bearing already has sufficient good lubricant 2) Grease hasn't reached bearing load zone; because fill tube is blocked or leaking, fill tube is large and not full, internal passage (holes in outer race) are blocked or you failed to wait for grease to reach load zone 3) Sound is dominated by internal friction or impacting not affected by lubricant 4) There is another source of ultrasound such as pump cavitation, seal rub, vee belts, or other mechanical or fluid process The ultrasound frequency near 39 kHz works fine for detecting lubrication and bearing faults. Walt |
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Walt's answer is pretty fully detailed. Just a few things to add as "possibles":
1. You do not have your MD in the ultrasound setting for the contact probe 2. You are trying to grease bearings which are sealed for death 3. You are working with plastic pipe extensions for the lubrication which will attenuate the signal. Have you been on one of SDT's training courses? I had the opportunity to attend one the other week and I was really impressed with the depth of understanding shown by Debra Smith,the trainer, in the complexities of lubrication. Best Regards, Tom Murphy |
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Thanks for the feedback guys...Wow, Debra really gets around! She was just in Las Vegas, Nevada USA and you say she taught a class in Manchester UK. Hope she likes to travel :-)
I am a vibe guy by trade and this ultrasonic just sounds like a lot of static. I have experimented with many machines that I know from my vibration data have issues and I cannot for the life of me hear anything more than static. SDT systems appear to be a leader in this technology but they sure drop the ball when it comes to just basic setup in there literature. I guess that is how they sell training. I am sure that this is not brain surgery; I was just expecting more concrete results. Thanks again... |
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STATIC? No change?
Send your equipment back to SDT. Its possible your cable, sensor, or internal problem with the unit. There really is not a digital unit currently, that is any easier to use than the SDT 170. P.S. Another reason for not hearing any change is the bearing is new (very little run-in time). The acoustic lubrication adaptor practice is meant to be used only as a service tool not for new installations. Good luck... |
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Paul,
There is great benefit to having an experienced person do a plant tour and show you the best procedure for using the ultrasound meter. I do provide this type of training. My advice is not to go to a specific machine and start greasing while looking for a change in ultrasound. I suggest that you first survey many machines and identify suspect bearing faults and poor lubrication and then grease the suspect bearings. I said earlier that I prefer the older model 150 meter. The reason is that when the new meter came out, it did not work as well for bearing faults. Perhaps the 170 meter and sensors now work better than the initial model release, but I haven't tested them since a few years ago. Interpretation of the audio in the headphone is in the "ear of the beholder". Some folks more readily learn to "hear" the ultrasound and extract a distinctive sound characteristic from the "static". It takes some practice and it is nice to know what to listen for. I often do a double machine survey, one for vibration and one for ultrasound. I try to optimize each set of measurements and then combine the results. I think this is important because you (like I did) have a bias with your vibration experience. One last rant: too many people either over simplify ultrasound and lubrication or they dismiss it because they never learned to do it correctly! Walt |
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From another forum
The UE2000 (another brand) has a three position switch (linear, log the other one I do not record) but our Instructor told us of a client who had the wrong setting for 3 years and it worked when finally a instructor showed them that there was nothing wrong with the equipment. The first thing I do: Test the equipment, is it charged?, if it has a airborne sound sensor, just rub your hands, or let someone hiss or whistle, blink with your eyes, adjust the intensity, you should be able to hear it. After that I test it with the contact probe. Steven van Els, CMRP |
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