Our course ‘Vibration Analysis 101: Waveforms, Spectrums, and Diagnostic Basics’ was very popular and participants posted many questions. Here are some we thought were worth sharing – from resource tips to resonance and beyond. 

Our course, ‘Vibration Analysis 101: Waveforms, Spectrums, and Diagnostic Basics’, opened a whole series that provides a technical deep dive into everything you need to know to apply vibration analysis to your CBM program.

Hosted by Augury’s own Nat Mills (Solutions Architect Manager) and myself, Andrew Pry (Solutions Architect), the series offers invaluable insights for those who are – or want to be – responsible for the health and performance of their facility’s machines.

This first installment started with the basics: the pros and cons of route based and online monitoring, how time waveforms turn into data that can diagnose common machine faults, and the knowledge you need to start your own vibration journey. While we dealt with some questions during the webinar itself, there were many quality questions left unanswered. 

So let’s deal with them here!

Is there a handy resource that collects most of the common faults you can detect as a VA? 

You are only a Google search away from finding what vibration frequencies typically look like for specific faults. You can purchase books, posters, and pamphlets from a vibration training company. There’s no one source-of-truth textbook that stands out. Every training company makes its own textbook, and all are slightly different in how the information is presented, but they mostly show the same vibration frequencies for each fault type. Often, you can buy these without taking the courses for a few hundred dollars – though you might have to go, for instance, to the Mobius Institute, as far as the checkout cart to cancel the certification course itself. The Technical Associates Of Charlotte also has a real nice looking wall chart – but yes, there’s a price tag. 

What is the minimum frequency/RPM that you believe vibration analysis is still an effective form of monitoring?

Like criticality, this is a machine-by-machine decision. There are a lot of gray areas. And while our confidence in detecting faults decreases at very low speeds, it also depends on the fault type that is developing and the specific machine geometry. If you want to know more about a specific machine, please contact Augury and we can help assess if that machine is a fit for your program. I should add, however, our list of applicable machines keeps expanding. 

When is it important to know the natural frequency of a rotating assembly?

When the natural frequency could possibly have frequencies that overlap with known frequencies on the machine, you should study the natural frequencies to check for resonance. And you’re not going to know when it’s a problem until you do the resonance analysis. You can’t look it up on a database with the model number of your pump to find its resonance frequency. It doesn’t work like that. There are so many variables that can play into it – even things as minor as the bearing clearances or auxiliary attachments/piping. Even a slight design change can have a massive impact on your resonance. 

Resonance becomes a problem whenever your operating frequencies start to overlap with natural frequencies – which is in fact the definition of resonance. So it’s those two elements you need to check. Resonance is in fact an ongoing conversation in Augury’s customer community The Endpoint – sign up to keep learning more!

How do we normally identify resonance faults? Is machine amplification the better way of troubleshooting it?

You can identify resonance faults by analyzing the structural natural frequency by modal impact analysis (aka bump test). You can also look for evidence of resonance by doing what’s called a “run up” or “run down” test, which operates a machine at all the ranges of frequencies and compares those running speeds to the vibration amplitudes. At Augury, we gather a bunch of different operating time stamps with a bunch of different frequencies, and basically recreate the “run up” or “run down” test with our large data set. Check out the article on Resonance in The Endpoint to see what this looks like. 

Motion Amplification is good for understanding where on the structure your resonance lies, and also what bending mode. It is a different analysis tool altogether, but also can be helpful in fixing resonance. 

Besides mechanically-induced vibrations, can you create vibrations from the electrical power source or due to miswiring of the motor?

Yes, The electrical signal in a motor can actually produce a mechanical vibration. But not all electrical faults can be detected with vibration monitoring alone. However, sometimes these faults can produce signals that might indicate a problem. The best way to catch an electrical fault is with motor current signature analysis, and monitoring the actual currents, voltages, power factors, etcetera – all the power details involved with the motor themselves from the motor control circuit. That is the best way to catch motor electrical faults. Mobius has a great video describing this phenomenon around how a motor’s electrical current can create mechanical vibration. I’d just begin by watching that. 

Watch ‘Vibration Analysis 101: Waveforms, Spectrums, and Diagnostic Basics’.
You can also continue the conversation on our community The Endpoint to learn more and ask questions directly

The post Ask A Vibration Analyst… No Really: Ask Me Anything  appeared first on Augury.

Why is measuring magnetic flux essential for interpreting vibration data related to the health of your machines? “It provides the context you and the AI need to make accurate and trustworthy predictions – without any false alerts,” according to Augury solutions architect (and VA) Andrew Pry. So why is measuring magnetic flux only now becoming a standard part of a VA’s toolbox?

Once upon a time, it was an easy call to know if a change in vibration on your rotating asset was something to worry about. You’d be in the factory, so when you registered a speed change with your handheld, you could do your own inspection or go to the operator and just ask if there were any changes. In other words, you could always check whether the machine is actually operating under the same conditions as when you last measured it. 

But there was a downside: you’d have to be very lucky to be on hand at that moment when a speed change signaled an impending problem that could cause unplanned downtime.

This is the power of constant remote sensing: you can pick up these changes in near real-time and then act in time to solve such problems before they become real problems. 

Welcome to the wonderful world of Machine Health.  

How To Stop Flying In The Dark

But with remote sensing, you don’t know what a change in vibration means. In fact, there are many possible reasons. With factories being noisy places, maybe it was just an overall change in external vibration. Or perhaps the endpoint moved. Or maybe management decided to push production as a prelude to a planned downtime. Or maybe it was those pranksters in Operations playing with their dials again… Etcetera.

This is all stuff you need to figure out when working remotely. Vibration analysts need multiple sources of information to properly interpret an asset’s condition in real-time. But this takes time and effort. It’s much easier if you have a single source to tell you all you need to know to make the best possible decision.

This is the magic of measuring the magnetic flux going through the motor concurrently with your vibration readings. If it’s there, you know the motor is running. As the alternating current fluctuates between positive and negative, you can then also calculate the actual speed of the motor… 

And now you are getting somewhere…

A Single Source Of – Constant – Truth

When I started at Augury a few years ago, we were the only ones measuring magnetic flux. People still needed to rely on their handhelds – and hope their manual inspection aligned with an impending problem so it could be caught. With Augury’s solution, the monitoring was remote, automatic, and constant. 

And with a continuous condition-based monitoring system comes many advantages. Instead of measuring, say, once a month, you’re measuring, say, every hour or less. It also opens up the opportunity to have one sensor giving you all the information you need – instead of relying on another outside source of information, may it be an operator or a whole other system. 

“I would love to describe the whole dance between vibration and magnetic flux. It fascinates me how their signals almost line up – even though they are seemingly wholly separate phenomena.”

The Dance Between Vibration And Magnetic Flux

If I had the space, I would love to describe the whole dance between vibration and magnetic flux. It fascinates me how their signals almost line up – even though they are seemingly wholly separate phenomena. And it amazes me how we can leverage this near-alignment to discover many interesting insights. 

For instance, we can measure slip. And as slip increases, we know the machine is working harder, and its power requirements are increasing. It could be a bad sign. But it could also mean a change in load. By knowing the difference, we can really reduce false alarms. 

And there are all sorts of things we have learned over the millions of machines we’ve monitored. Let’s give two examples… 

Case Study #1: Avoiding The Unsweet Spot

On one level, the measuring of magnetic flux was developed as a way to automate continuous monitoring, but it was also developed so we could track a machine’s vibration against its different speeds to determine whether it has a resonance condition – a whole topic in itself. 

Each machine has its own natural frequency, and if you operate that machine at a speed that coincides with that natural frequency, this causes resonance – which creates a whole lot of vibration.

Happily, we can avoid such situations – and thereby likely extend the life of a machine – by paying attention to any machines that have seemingly big and random vibration spikes. If we pull up the magnetic frequency data to see how fast the machine was running at all those different times, we often discover the machine was actually running at the same speed each of those. Now, we’re sure it’s a clearcut case of resonance. 

Our customers can then choose to avoid that speed in the future, or re-engineer that particular machine to change its natural frequency.  

“Pump happy, we’re happy.”

Case Study #2: Re-Establishing The Sweet Spot 

Many of us know pumps are fussy beasts – and almost human-like in how they hate change. Pumps like to operate in a sweet spot called best efficiency point (BEP). That’s the point where, hydraulically, the pump is in its most stable condition. 

I remember one time, a chiller water pump had undergone maintenance, and when it was turned on, it produced a lot more vibration than usual. Here, you worry about cavitation, a potentially catastrophic implosion on a piece of metal inside the machine. The maintenance team was warned, and they investigated. It turned out the tank levels were not right so they made the required adjustments to put the pump back into its ideal flow conditions.

Thanks to measuring magnetic flux, we could remotely detect an operational change – not just a speed change. Pump happy, we’re happy. 

“What makes Augury technology so powerful is how we’ve built out hundreds of such ‘feature sets’ that help account for our nearly 100% accurate diagnostics. And many of these are thanks to measuring the magnetic flux.”

Now, To Bring The AI Up To Speed

In the name of automation – and making everyone’s job easier – we take these clearly interpreted scenarios we discover and train our AI to recognize them. In other words, we flag those things that the AI should pay attention to, so then, if needed, the algorithm can flag those situations that the maintenance team should look at. 

What makes Augury technology so powerful is how we’ve built out hundreds of such “feature sets” that help account for our nearly 100% accurate diagnostics. And many of these are thanks to measuring the magnetic flux. 

So, consider this a public service message: if you are not yet doing it, measuring magnetic flux is a crucial part of understanding vibration analysis. It’s a particularly powerful tool if you take this measurement at the same time you’re measuring the vibration because you can more easily correlate these two very interdependent variables and gain all sorts of real-time insights.

Fortunately, for both manufacturers and their machines, this approach is becoming an industry standard. But yes, it’s a whole other job to gather enough information to build out an AI that can turn all this information into accurate and reliable actionable insights.

All hail, magnetic flux. 

To learn more about vibration analysis, check out our webinar series.
To learn more about our approach, just reach out!

The post It’s Not All About Vibration. All Hail Magnetic Flux! appeared first on Augury.