Wednesday, July 19, 2017

Top 10 Reasons Why a Strobe Light is an Analyst’s Best Friend: #5 – Belt Drives: Bent Shafts and Pulley Wobble/Runout

Although a dial indicator would be the preferred method for accurately determining the degree of faults like these, a strobe can often help when the machine cannot readily be shut down. We start with the same basic Slow Motion Study approach (are you sensing a pattern…?)

Starting with the driven shaft, by lining up the edge of the pulley or shaft with a fixed point on some structure behind it, you can watch for any movement of the shaft that shouldn’t be there in both the radial direction (runout, eccentricity, bent shaft, etc.) and the axial direction (cocked pulley, bent shaft, etc.).


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

Come back to our blog next week to read #4 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, July 12, 2017

Top 10 Reasons Why a Strobe Light is an Analyst’s Best Friend: #6 – Structural Looseness

Ever see amplitudes increase drastically at 1x? Did you know that a strobe light is a great way to inspect for structural looseness, often the cause of such a sudden increase (literally – something broke)? To do this, we utilize the very same Slow Motion Study techniques we discussed previously.

By tuning to the frequency of interest and then tuning slightly away from that, you will be amazed at some of the things you can see happening on the structure. Sometimes you need to play a bit with your flash rate but you will find this to be a useful technique in finding broken welds, loose feet, housing distortion, loose and broken fasteners and many more causes of abnormally high amplitudes.


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

Come back to our blog next week to read #5 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, July 5, 2017

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.



Wednesday, June 28, 2017

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.



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!