Case Study #1 Electrical Vibration Problem

Hello Everyone,

As promised and to follow up on my previous post on bearing failures here is the first of five technical detailed case studies presentation. This is my first voice over presentation so please excuse the English Farmer accent mixed in with some Australian twang.

These case studies are to support my book ‘Enhanced System Reliability Through Vibration Technology’ and my new role as an RMS Trainer with the RMS Reliability Training Institute.

Many thanks to Dr Jezdimir Knezevic from MIRCE Science for his enlightening discussion (and MIRCE Science) and to Austin Dunne from Infrared Training Limited for his guidance and to Dean and Stuart at RMS for all their support.

The case study can also be viewed on the RMS website.

Bearing Failure Examples

Hello everyone, I have created short presentation to share some different bearing failures that were detected before function failure. This has been put together for meetings and toolbox talks to promote the benefits of what defects a condition monitoring program can detect. Every bearing here has a story of how it was detected and what actions were/were not put in place to protect the functionability of the system.

This is aimed to highlight (at a high level) to management and production what we can detect if a suitable system is set up correctly.

I am working on another case study presentation that follows up on these and some other cases. In this one it will have the technical testing data (thermal, electrical and vibration) and a full case study also showing the ‘The Cause’ ‘The Mechanism of Failure’ and ‘The Failure Mode’. This will be posted over 5 videos.

Please feel free to share and spread the knowledge

Increase your Plant Reliability with a Seasoned Analyst

Increase your Plant Reliability and Increase Profit with a Seasoned Analyst.

Do you have unplanned failures? – How much is this costing the company per hour? – Do you have any repeat failures that causes disruption to production? – Are you firefighting faults? – Do you have any equipment that is vibrating heavily that you can’t reduce? – How can you improve your current maintenance practices?

Many companies don’t have the expertise of a Seasoned Analyst to help them increase Plant Reliability via an effective Condition Monitoring Program. Attached is a PDF that contains information that can assist you in this.

With over 30 years’ experience in the fields of Vibration Analysis, Infrared Thermography, Condition Monitoring and Maintenance Engineering I have put together a book that your Engineers and Maintenance Team will find extremely useful. Having worked with many of the Blue-Chip companies in the UK and Australia, I have collated my experiences to help and support the Non-Seasoned Analyst.

My experience ranges from Lubrication, Thermal Imaging, Vibration Analysis, Ultrasound, NDT, Maintenance Planning, Maintenance Improvements, Project Management and Mechanical Maintenance including on site Dynamic Balancing and Laser Alignment.

I can provide an integrated condition monitoring support service that will manage and drive your maintenance tasks through Health Based Maintenance. This will enable you to know the health of your system, engineer out repeat defects and increase production uptime.

Please read the attached book flyer for more details of how we can help you and your team. If you require further information, please contact us

A profitable plant is reliable, safe and a cost-effectively maintained plant

The Seasoned Analyst

Enhancing System Reliability Through Vibration Technology

A profitable plant is reliable, safe and a cost-effectively maintained plant

The Seasoned Analyst

I have put together a 4 page document to explain why I wrote my book and also what the content is. Please download the PDF below and have a look.

Enhancing System Reliability Through Vibration Technology – The Book. UPDATE!!

We have managed to secure discounted postage with the printing company direct, this update has the new reduced postage costs.

ISBN: 978-1-5272-5386-5

This technical reference book comprises of over 20 years’ experience in the fields of Vibration Analysis, Condition Monitoring and Reliability Engineering. It is written with the technical tradesperson in mind, interpreting Vibration principles into layman’s terms. It has taken 7 years to fine tune the book and I have been though three demo versions. This is the first published version.

All data is from real-life situations with over 20 case studies throughout the book. This is to be used as material to help support knowledge sharing, practical training and mentoring to enhance System Reliability though Vibration technology

This publication comes as an A4 300 page Paper Back printed in full colour on 120gsm paper.

Book Content:

  • Part 1: Introduction to Condition Based Maintenance
  • Chapter 1 – Condition Monitoring
  • Chapter 2 – Mechanics of Failure
  • Chapter 3 – Condition Monitoring Technologies
  • Part 2: Condition Monitoring Management Processes
  • Chapter 4 – Setting up and Reporting
  • Chapter 5 – Practical Application
  • Chapter 6 – ISO Standards 
  • Part 3: Vibration Analysis Condition Monitoring Techniques
  • Chapter 7 – Vibration Units 
  • Chapter 8 – Accelerometer Selection and Mounting
  • Chapter 9 – Signal Processing 
  • Chapter 10 – Bearing Condition Units 
  • Chapter 11 – System Dynamics 
  • Chapter 12 – Resonance & Natural Frequencies
  • Chapter 13 – Operating Deflection Shape Analysis
  • Chapter 14 – Motion Amplification
  • Chapter 15 – Modal Analysis Chapter 16 – Orbit Plot 
  • Chapter 17 – Bode Plots 
  • Part 4: Performing Vibration Analysis  
  • Chapter 18 – General Vibration Analysis  
  • Chapter 19 – Rolling Element Bearings 
  • Chapter 20 – Fluid Film Bearings 
  • Chapter 21 – Gears        
  • Chapter 22 – Paper Machines    
  • Chapter 23 – Jaw Crushers    
  • Chapter 24 – Vibrating Screens 
  • Chapter 25 – DC Drives 
  • Chapter 26 – AC Drives 
  • Chapter 27 – Electrical Discharge Machining (EDM)       
  • Chapter 28 – Pumps       
  • Chapter 29 – Compressors    
  • Chapter 30 – Reciprocating Engine Vibration   
  • Chapter 31 – Turbo Machinery Notes 
  • Part 5: Balancing  
  • Chapter 32 – Balancing   
  • Part 6: Appendix
  • Chapter 33 – Case Studies

Please complete the form below with your location, question or number of copies required and we will respond with the costs for postage and packaging.

For a limited period, the costs for this book is at a reduced price of £44.50 (RRP £75) plus postage when purchased direct

  • Postage to the UK is £4.45
  • Postage to the EU is £9.45
  • Postage to the Rest of the World is £13.45

Payment is though PayPal

Please complete the form below with your location, question or number of copies required and we will respond.

A profitable plant is reliable, safe and a cost-effectively maintained plant.

The Seasoned Analyst

CBM Conference Manchester, UK 7-9 October 2019

A profitable plant is reliable, safe and a cost-effectively maintained plant.

The Seasoned Analyst

CBM Conference 2019 UK

I presented at my first Conference, and it was the first CBM Conference in the UK. It was well worth attending as I got to discuss various challenges in the condition monitoring and reliability sector, and the most common discussion point was buying from senior management and how to continually highlight the benefits of a condition monitoring program.

In addition there were vendors there demonstrating the latest advancements in condition motioning technology from vibration online and walk around, thermal imaging safety, ultrasound new high sampling rates time waveform analysis to motor electrical condition monitoring.

More information can be found here on the conferences and this web site is great for condition monitoring information

My Presentation was on a case study solving a reliability issue at a pumping station by designing and using a Dynamic Vibration Absorber. You can download the presentation below.

And these are the videos in the presentation.

Slide 23: Side by Side Comparison
Slide 24: Bed Plate
Slide 25: Upside down base plate
Slide 32: Live Speed
Slide 33: Slow Motion

If you do get the opportunity to attend a CBM or Reliability conference I fully encourage it.

A profitable plant is reliable, safe and a cost-effectively maintained plant.

The Seasoned Analyst

The Human Senses in Online Vibration Monitoring

When all else fails, leave the air conditioning, and go examine the operating equipment. Go look, touch, feel, smell and listen to the machinery.

The seasoned Analyst


Online vibration monitoring is a great tool that enables monitoring of a vast number of assets, it helps the analyst when they “can’t see the woods for trees”.

This post is to highlight that for a full assessment of an asset you don’t just sit in your air conditioned office looking at the data on the screen. You must use other technologies and inspection tools to assess the Reliability of the system, the best tool is experience and your human senses.


The SPM online system alarmed on a fan bearing. This fan has a direct drive AC motor to a fan lay shaft with two SKF/Cooper split bearings.

The onsite vibration analyst called for an inspection of the bearing due to mechanical/component looseness and an outer race defect. I was asked to confirm the diagnosis and provide further details.

Pre-Vibration Analysis:

On review of the data, and the new on demand live data, from the SPM system I concluded that the analyst was correct in the diagnosis of mechanical/component looseness and an outer race defect on the split bearing.

Figure 1 is the SPM online Velocity spectrum from the 1st September, with low overall one order and no harmonics.

Figure 1 – Before the online alarming

Figure 2 is the SPM online Velocity spectrum on the 3rd September, and shows many running speed harmonics indicating a component/mechanical looseness.

Figure 2 – After the online alarming

Inspection :

Before I issued my comments I decided to “Leave the air conditioning, and go examine the operating equipment. Go look, touch, feel, smell and listen to the machinery”. Within seconds I spotted the issues and using my personal Motion Amplification tool, my finger! I felt and confirmed what my eyes were seeing.

Image 1 is of the drive end (Motor side) split bearing, all good.

Image 1 – Fan DE bearing (Motor Side)

Image 2 is of the fan NDE bearing (Fan side). The top cap retaining bolts were coming loose!

Image 2 – Fan NDE Bearing (Fan Side)

Corrective Actions:

This was reported immediately to the on site maintenance team. Maintenance re-secured and torqued the bearing top cap bolts. It was found that both bolts were loose!

Post Vibration Analysis:

Figure 3 is the SPM online Velocity spectrum after the corrective actions, 3rd September. This shows a large reduction in the 1 order harmonics, confirming the loose bolts were the cause of the harmonics. It was also noticed that there were still some higher frequency data evident that was not there prior to the 3rd September.

Figure 3 – After the bolts were tightened

Further analysis of the SPM HD Envelope spectrum displayed a clear defect signal for the outer raceway. This is a split bearing so you would expect to see some bearing signal but the fan end is a lot higher. This is not surprising giving that the fan end bearing was in operation with a loose top bearing cap!

The data below compares the drive end (motor side) Figure 4 and non-drive end (fan side) Figure 5 SPM HD Envelope spectrum. This confirming that the fan end bearing signal is a lot higher.

Figure 4 – Drive end bearing (Motor Side)
Figure 5 – Non-drive end bearing (Fan Side)


This highlights that there is a place for an online monitoring system in some aplications.

In addition to preventing a catastrophic failure of the fan and this having a effect to the profitability of the site, this prevented what could have been a very dangerous safety incident with a fan coming loose at full speed.

For a full assessment of the system please leave the air conditioning, and go examine the operating equipment. Go look, touch, feel, smell and listen to the machinery. Don’t site and rely on one form of data to make a decision that will affect the reliability and probability of the system.

A profitable plant is reliable, safe and a cost-effectively maintained plant.

The Seasoned Analyst

A vibration analysis program case study utilising SPM HD Enveloping.

A profitable plant is reliable, safe and a cost-effectively maintained plant.


I often am lucky enough to use different vibration technologies and this post is a great example of how a vibration analysis program can protect the business using the SPM HD Enveloping technique. This post is with thanks to assistance from Dean Whiteside.


As part of a routine vibration data collection program a change in condition was noted at the fan motor vibration levels. Vibration monitoring frequencies were increased to daily as the defect deteriorated. This enabled planning and a controlled change out of the motor.

Air Fan

Vibration Analysis:

On inspection of the vibration data, bearing outer raceway (BPFO) damage was diagnosed at the drive end motor bearing. This was clearly evident in the SPM HD Enveloping.

Acceleration Data:

Figure 1 shows the Acceleration RMS trend from the motor drive end (DE) bearing location. This shows the steep increase in the impacting levels with an exponential increase in the final days of monitoring.


Acceleration RMS Trend

SPM HD Enveloping Data:

Figure 2 shows the SPM HD Envelope spectrum from the motor drive end bearing. This technique shows a clear impact at 3.09 Orders that matches the defect frequency for the bearing fitted. There are many harmonics indicating a very impactive signal.

Fig 2:

SPM HD Enveloping

Summary of vibration:

There is a clear distinct defect in bearing outer raceway, at these levels this would confirm a spalling to the raceway.

Corrective Actions:

Due to the risk of failure, a new motor was sourced and placed on-site encase of instant catastrophic failure. The risks was discussed with production and was deemed too high to the process and a plan was put in place for a controlled stop. But prior to this date there was an unexpected line stop, and as the motor was all prepared on site, the motor was changed during this downtime.

Vibration data after controlled change-out:

Figure 3 are the SPM HD Enveloping spectra from before and after motor change out. The top plot showed the clear bearing damage and now with the replacement motor there are no bearing defect signals present.

Fig 3:

Original Motor
New Motor

Figure 4 is the Acceleration trend from the motor drive end bearing location. This trend shows the increasing and then the lowest record level with the new motor installed.

Fig 4:

Acceleration RMS Trend

Bearing Inspection: After sectioning and cleaning

On visual inspection, it was found as expected, a large visible defect in the loadzone of the bearing outer raceway. Motor Drive End Bearing FAG 6316-C3

Image 1 is the drive end bearing sectioned.

Image 1:

Drive End Bearing

Image 2 is the defect located in the loadzone of the outer raceway.

Notice the flat bottom of the spalled area and the “neat” cracks around it. These are cracks that have come to the surface and in time, more material will break away.

Image 2:

Microscopic Image Outer Raceway

Image 3 is the defect located in the loadzone of the outer raceway.

Particle over roll as the bearing comes out of the load zone.

Image 3:

Microscopic Image Outer Raceway

Failure Mode:

ISO 15243:2004: 5.1.2 Subsurface initiated fatigue. Primary causes of Subsurface initiated fatigue are repeated stress changes and material structural changes. This leads to microcracks under the surface, crack propagation and then spalling.

This bearing was close to catastrophic failure

The bearing is damaged as soon as spalling occurs. Spalling gradually increases and gives rise to noise and vibration levels in the machine. This machine was stopped and repaired before the bearing collapsed. The period from initial spalling to failure depends on the type of machine and its operating conditions.

What is sub surface fatigue? In a rotating bearing, cyclic stress changes occur beneath the contact surfaces of the raceways and rolling elements. Consider the rotating inner ring of a radial bearing with a radial load acting on it. As the ring rotates, one particular point on the raceway enters the load zone and continues through an area to reach a maximum load (stress) before it exits the load zone.

During each revolution, as that one point on the raceway enters and exits the load zone, compressive and shear stresses occur. Depending on the load, temperature and the number of stress cycles over a period of time, there is a build-up of residual stresses that cause the material to change from a randomly oriented grain structure to fracture planes.

In these planes, so-called subsurface microcracks develop beneath the surface at the weakest location, around the zone of maximum shear stress, typically at a depth of 0,1 to 0,5 mm. The depth depends on the load, material, cleanliness, temperature and the microstructure of the steel. The crack finally propagates to the surface and spalling occurs.


This is another example of how vibration technology and knowing system health and risk of failure enables data driven decisions to benefit the business. The motor was replaced when the line was down due to an unplanned shutdown, with no additional downtime occurred.

If this motor had failed without any planning this would have lost product and reduced profit. In addition these actions have protected the customers, supply chain and brand our reputation.

A profitable plant is reliable, safe and a cost-effectively maintained plant