Ultrasonic detectors, the real deal?

Applying grease by means of sonic or ultra-sonic frequency is a great method to reduce over greasing or assure that the bearing has proper amount.
BUT don't you have to have a baseline prior to implementing the use of the lubrication by frequency? Bearing manufacturers should supply the alarm frequency info but not the baseline for normal operations.
I have been contemplating the use of applying grease by means of frequency. From what I have been told/discovered, first a baseline (frequency) for all greased bearings must be established & entered into a data base. Then the use of ultra-sonic frequency is used to apply the proper amount of grease per application by set alarm limits. This can turn into a major project in any large industrial site. But the end result is worth the effort.

I have purchased the Ultra-Lube 2000 device for use at our plant. We are just providing training on it now. The specifications on the device are included at the website www.UVLM.com. The use of the acoustic device is quite subjective. There are some guns that have scales to measure the sounds coming from the bearings. I have encountered some resistance from the crews but that happens with every change. We may look into hooking the device up to a scope to get a more objective reading from the sounds. The specs that we have state that the frequency range is 20Hz to 20 kHz.

Randy,

Thanks for the input. Seeing the frequency range in vendor specs is what we were looking for.

Do you happen to have mini-mess or similar sample devices at your plant? If so how did you get them installed? If you could contact me about this subject, I up dated my profile with my email.

I am currently involved in a project of installing mini-mess sample ports in the gearboxes of plant I work at. Each unit has to be looked at to determine the best location to put it in. But for most applications I will place the valve in the drain port. I am using the type with the swivel tube extend to place the end of the tube into an active area of the oil splashing around inside the gearbox. By bending the tube slightly away from the bottom of the gearcase we are not sampling the sludge which collects there. On circulating systems you ideally want to place the sample ports in return lines before any filters or the reservoir.

I have started a program where I accompany the maintenance people on their grease PM's for a handful of critical 24/7 equipment. I go down the machine and record "as found" ultrasonic readings and determine which bearings need grease. I listen while the grease is applied and stop the addition when a step change is heard. After lubricating all the bearings on the machine I go back and take additional readings and add more grease if I feel it is warrented. I recently bought a $2.50 headphone splitter so the mecahnics can also hear whats going on in the bearings when they apply grease. Works great and has eliminated grease related failures for 2+ years.
rgf

I'd like to get the discussion of these lubrication monitors going again. What are the thoughts on these devices. Do they really do what they claim? The real question is "can lube techs listen to bearings and reliably determine if a bearing needs to be greased before there is damage to the bearing?" What manufacturers equipment are you using? I know SDT has a package for bearing monitoring, UE has a gun adapter, and UVLM has one also. I am in the the middle of putting together a comparison report on these lubricators and have basically been researching all I can find on them for the past two months.

Another item that has been bothering me about these lubricators is the fact that the three manufacturers all focus their frequency responses in different ranges. For example, UVLM's monitor is purely acoustic, where as UE's is centered around 40 kHz. Makes you wonder what sort of differences would appear appear if you compared them side by side while greasing bearings of exact same condition. Would one gun indicate that more or less grease is needed than the other??

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Originally posted by Pete:
Randy,

Thanks for the input. Seeing the frequency range in vendor specs is what we were looking for.

Do you happen to have mini-mess or similar sample devices at your plant? If so how did you get them installed? If you could contact me about this subject, I up dated my profile with my email.

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We are in the process of installing mini-mess valves and desiccant breathers at Harris. I did it with a generic plant mod with individual "checklist" and maintenance work order for each piece of equipment. It has worked well for us. If you need additional info, call me at (919) 362-2314.

We have used a 'sonic' attachment to a standard grease gun. This has been a very productive tool for us. It is a quick way to check bearings without the need of taking and analyizing all of the vibration data. Also, when you spot a problem the sonic grease gun helps you to put in the correct amount of grease. The use of the sonic grease gun works will in tandem with our vibration analysis. Each calls on the other to verify findings or to aid in the troubleshooting analyis. The downside is that it is user specific. Not everyone could pick it up, listen to a bearing, and have the same analyis. It definitely takes some use before a person understands what he is listening to and can act appropriately. It took less than a month for our primary user to become proficient.

I work for a large foundry in the automotive part supply business. We use the SDT model. It provides both audio output (to the user through headphones - subjective) and a digital readout of the actual decibel reading (objective). We have found it extremely useful for determining proper grease quantity and frequency and we use both the audio and the digital outputs. We also use it for "quick" fault detection and for confirmation. It measures a range from 38 to 42 kilohertz.
Warning, there are a bunch of other reasons why you would get a high ultrasound reading (bad bearing, misalignment, imbalance, etc.) so high readings do not necessarily mean there is a grease problem.
That being said, too much grease or not enough both produce high ultrasonic outputs which the SDT provides on the digital screen - output in decibels. Like I said, both give high readings, but, they "sound different" ... Listen for a while and you will begin to train your ear - there is really no other way to learn.
It works best if you start a program and learn as you go. Try using it on a brand new installation that is balanced, aligned, bearing is new and was properly "packed" with grease - now you know what it is supposed to sound like and you have a "perfect" reading in decibels for that bearing. The reading is only applicable to that bearing though, others may naturally run higher, the sound is generic and applicable to all. Next, listen to a bearing you know is bad, one that you know is over filled, one that is dry, one that is misaligned, one that is out of balance... You get the idea.
Your ultrasonic supplier should be able to provide sound bites for you to listen to but still there is nothing like the real thing and no substitute for experience.
As for the decibel output - trend readings on a particular bearing are all you can go by... I have had ones run as low as 25 and some as high as 45 when they are good... Generally a 10 decibel increase warrants action - try greasing it to see if it goes back down. If it goes up, you have too much grease. If it goes down, you keep adding slowly until it reaches a minimum and begins to go back up. If it does not change - you have something other than a grease problem.

SPM, brand name ultrasonic vibration analysis equipment does not need a baseline to determine adequate lubrication. You take a reading before lubing, lube it, take another reading and it will tell you whether the lube made a difference based on the readings. If you have two people, one can take a series of continuous readings, while the second person lubes, you can detect when the bearing received the lube and when no further improvement is read, when to stop. The last part is best done in stages to prevent overlubing. We bought SPM and like its ease of use in bearing analysis and lubrication issues. I am primarily the welder here and was the one who pushed for the device based on ease of use

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Originally posted by Pete:
Anybody have much experience with ultrasonic grease guns?

At what frequencies do they detect bearing noise? Is frequency even play a part in ultrasonic detection?

Would it be better to purchase an ultrasonic grease gun or just an ultrasonic gun (more uses)?

Our concern is that by the time the ultrasonic detects noise bearing damage may be occuring. I personally would like to try one but, one of our lead vibe guys is skeptical of the whole set up. We are having trouble finding out at what frequencies and db they detect, as related to vibration analysis.

Thanks for any input.

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The frequency range will vary depending upon manufacturer, but generally 30 to 32KHz is recommended for mechanical inspections. For steam on other contact listening like electrical scan through a metal cabinet(20 to 30KHz) for open air electrical and leak detection (close to 40KHz).

I would purchase an ultrasound listener for the ability to use it for electical scans, leak detection, and mechanical applications (espeically since you are in a power generation plant). You can always get a lubrication fitting as optional equipment or you can make one. There are two to three good manufactures depending upon you applications.

Before base line readings are collected, it is recommended that lubircation be performed and given one to two weeks for the lubrication to take. Then baseline readings can be taken ... You are baselining the bearings at their "best" condition (albeit some wear will be evident on certain bearings). It is important to remember that each time you collect ultrasound readings, that the equipment is at the same load / rpm as the time before as this will affect your readings. Keep records as to operting condtions at the time of sampling and also instrument settings. You want to repeatable sampling program.

Ultrasound, if used properly, can filter very quickly and cheaply which equipment should be scheduled for vibration.

Thanks