Top 10 Reasons Why a Strobe Light is an Analyst’s Best Friend: #7 – Verifying 1x

One mistake I’ve seen made over and over is an analyst fails to verify that what they believe to be 1x is actually 1x. This happens for one simple reason: more than one single flash rate will cause a single mark to appear. What about 1/2x, when the flash rate is once every two rotations? Or 1/3x?

The simple test is to double your flash rate from what you believe to be 1x. If two marks appear, meaning you are now flashing twice per rotation, you are correct. If not, you have more work to do.

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

Come back to our blog next week to read #6 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.

Top 10 Reasons Why a Strobe Light is an Analyst’s Best Friend: #8 – Rotational Direction

Have you ever been in a situation where something strange was happening operationally on a machine and you wanted to make sure it was running the right direction (wired properly) but you didn’t want to shut it down? A strobe light is an easy way to check rotation without shutting down.

By flashing the strobe light at slightly less than its running speed, the rotor will make slightly more than one rotation between flashes. That means your mark will progress in the direction the fan is actually running and allow you to determine whether the motor is wired properly or not.

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

Come back to our blog next week to read #7 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.

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 ~ VFD_OUTPUT x [2xLF_Hz  / # 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.

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.

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!

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.

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.