Wednesday, June 21, 2017

Top 10 Reasons Why a Strobe Light is an Analyst’s Best Friend: #9 – Inspections

Strobes allow you to inspect a running machine in detail, also known as a “slow motion study”. The first step is tuning the strobe light to 1x, which should be at least roughly available. When you get there with the strobe, the shaft will appear to stop. If it is on a VFD, you can estimate the RPM use the following formula:        
RPM ~ VFDOUTPUT x [2xLFHz  / # of Poles]


Once you know the speed, tune it slightly away from that frequency and components will appear to rotate in slow motion, allowing for inspection of couplings, belts, fan rotors, pulleys and much more. 


This tip is provided by Scott Dow, Senior Instructor of Mobius Institute.

Come back to our blog next week to read #8 in our Top 10 Reasons Why a Strobe Light is an Analyst's Best Friend. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com.



Wednesday, June 14, 2017

Top 10 Reasons Why a Strobe Light is an Analyst’s Best Friend: #10 – Speed Checks

A strobe light is often an analyst’s best friend. Over the next few tips, we will go through a variety of useful functions.
First and foremost, a strobe light is a convenient way to get an accurate speed as you are collecting the data. The importance of an accurate speed cannot be overstated since the error is multiplied by orders. So recording an accurate speed allows you to confidently calculate forcing frequencies, both synchronous and non-synchronous.
Secondly, with VFDs becoming increasingly common, the strobe allows you to assess the consistency of the motor’s speed. Depending on system requirements, VFDs can change speeds incrementally in an instant, which causes peak-spreading and other issues.



This tip is provided by Scott Dow, Senior Instructor of Mobius Institute.

Come back to our blog next week to read #9 in our Top 10 Reasons Why a Strobe Light is an Analyst's Best Friend. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com.



Tuesday, June 6, 2017

IMVAC Europe 2017 Kick-Off!

IMVAC Europe 2017 started today, June 6, 2017 with a keynote by Herman Baets, Company Manager/Independant Consultant, MRT on "Challenges for Maintenance in a Changing World."

The first day of the conference featured five workshops (half and full day) and was followed by a Networking and Welcome Reception.

We are looking forward to an excellent day two of IMVAC Europe - check back here and on social media for more updates this week!




Wednesday, May 31, 2017

Condition Monitoring Expert Tip #10 - I use a laser alignment system, so I am performing precision alignment, right?

No, sadly, that is not right. Unless the person has been properly trained, and unless the company has specified precision alignment tolerances, and unless the training is followed and the tolerances are achieved, then you are not performing precision alignment.

We see this as a very common problem. Laser alignment systems can achieve terrific results. And a precision aligned machine is far more reliable than a machine that has been “roughly” aligned with an alignment system, and far superior to a machine aligned with a straight edge. But if your maintenance technicians do not appreciate why that last shim should be installed, and why the motor must be moved such a small amount to the left or right, then those corrections will not be made - and yes, it does matter.

Research by Tedric A. Harris, in the book “Rolling Element Bearing Analysis” (John Wiley & Sons) showed that just 5 minutes (5/60 of a degree) of angular misalignment can reduce the life of a bearing by half. Yes, precision matters.




This tip is provided by Jason Tranter, Managing Director of Mobius Institute.

For more condition monitoring tips, continue to visit the IMVAC – International Machine Vibration Analysis Conference – blog every week. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com.



Wednesday, May 24, 2017

Condition Monitoring Expert Tip #9 - My spectrum does not indicate misalignment so my machine is aligned, right?

No, sadly, that may not be correct. If the spectrum (and phase readings) indicate misalignment, then the machine will be misaligned. But if there is no indication of misalignment, the machine may still be misaligned. I know that may not make sense, but unfortunately it is true.


A number of experiments have been performed where real machines were misaligned and the vibration pattern did not change. The vibration pattern depended upon the type of coupling and other conditions, but the bottom line is that the only way you can be sure that the machine is precision aligned is to precision align the machine.



This tip is provided by Jason Tranter, Managing Director of Mobius Institute.

For more condition monitoring tips, continue to visit the IMVAC – International Machine Vibration Analysis Conference – blog every week. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com.



Wednesday, May 17, 2017

Condition Monitoring Expert Tip #8 - Is it important to use wear particle analysis?

First, it is important to monitor the condition your lubricants. You can test the chemistry to determine if the lubricant can continue to do its job. You can also detect contaminants, both particles such as dirt and fluids such as water, because they can harm the lubricant and harm your machine. But if your oil analysis includes particle counting and can detect metallic elements, do you also need to perform wear particle analysis? The short answer is “yes”.

When wear occurs within a machine, small particles are generated. The shape, size and color of those particles indicates where they have come from and how and why they were created. For example, if contaminants caused the wear, the particles will look different to particles generated if there was excessive load. There is an “atlas” available that illustrates what the particles can look like.


The process used to count the particles, which is an important oil analysis test to perform, does not provide an indication of the nature and origin of the particles. And when the oil analysis report indicates that elements such as iron and tin are present, that is only because there were very small particles, less than approximately 9 ┬Ám in size, present in the oil. The wear particles we are talking about are a lot larger in size. When these wear particles exist, you may not see any real indication in the standard oil analysis report, and the information gained does not provide the critical diagnostic information need.



This tip is provided by Jason Tranter, Managing Director of Mobius Institute.

For more condition monitoring tips, continue to visit the IMVAC – International Machine Vibration Analysis Conference – blog every week. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com.



Friday, May 12, 2017

Condition Monitoring Expert Tip #7 - Why do I need to use time waveform analysis?

Spectrum analysis provides a great deal of information about the health of rotating machinery. But you should consider the spectrum as a summary of the vibration within the machine.

The Fast Fourier Transform takes the time waveform and computes how much of each frequency is present and displays that as a line in the spectrum (grossly summarized, but that is basically the case). Therefore, if the vibration from the machine is generated by smooth periodic motion, then the spectrum provides a very good representation of what is happening inside the machine. But as damaged gears mesh together, and rolling elements pass over damaged areas on the raceway of the bearing, and as the pump vanes push through the fluid causing turbulence or cavitation, the vibration generated is not smooth and periodic. And there are a lot of other fault conditions that likewise do not generate smooth and periodic vibration. Thus, the only way to really understand what is happening inside the machine is to study the time waveform.


The time waveform is a record of exactly what happened from moment to moment as the shaft turns, the gears mesh, the vanes pass through fluid, and the rolling elements roll around the bearing. Each minute change that results from impacts, rubs, scrapes, rattles, surges, and so much more is recorded in the time waveform and then summarized in the spectrum. Therefore, it is critical to record the time waveform correctly and analyze it when you have any suspicion that a fault condition exists.


This tip is provided by Jason Tranter, Managing Director of Mobius Institute.

For more condition monitoring tips, continue to visit the IMVAC – International Machine Vibration Analysis Conference – blog every week. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com.