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Machine vibration problems reviewed

When looking at machine vibrations it is always necessary to be able to distinguish between normal operations and emerging problems.

Vibration can be symptomatic of a problem, or it can be the cause of a problem. There are times when the machine isn’t physically vibrating and there is a problem. In general, most systems are designed to avoid vibration as opposed to creating it. (Excluding shakers and screens of course!)

Vibration Analysis Courses are designed for reliability engineers, PdM program managers, and other maintenance staff who would like to understand condition monitoring with a focus on vibration analysis.

4 common machine vibration problems

Vibrating machinery, left unchecked, can speed up the deterioration rate of parts or cause damage to the system that may require key components of a machine to be replaced.  There are quite a few causes for why machinery may start vibrating, here we are going to look at the four most common reasons.

  • Wear

With rotating components like roller or ball bearings, gears, or drive belts, when these components start to show signs of wear the machine vibration vibration patterns and levels change, mostly increasing in vibration.

For example, if a roller bearing race becomes pitted, then the bearing rollers will generate impacting and frictional machine vibration. This occurs as the rolling elements travel over the section of pitted race. Other examples of wear causing vibration include: a drive belt breaking down, or a heavily worn or chipped gear tooth. These both generate a different increase and pattern change in the vibration signature.

  • Unbalance

If a rotating component has what is known as a heavy spot this can cause machine vibration, this increases exponentially with speed. Unbalance is when the shafts geometric centreline and mass centreline do not coincide. The reason for this is because the heavy spot will force the mass centreline off the geometric centreline.

Unbalance can be caused by a few different things, such as:

  • maintenance issues: missing balance weights or dirty or deformed fan blades.
  • manufacturing defects including casting flaws or machining errors.

The effects of an unbalance will become greater as a machine’s speed increases. The biggest concern with unbalance is that it can cause unnecessary machine vibration and drastically reduce the operational life of bearings.

  • Looseness

Looseness can be Rotating or Mechanically generated.

There are three types of Mechanical looseness to consider: Rotating looseness, Structural looseness (foundation flexibility) and Non-rotating looseness. Rotating looseness can occur due to wear in a bearing.

The problem with looseness is that irrespective of what caused it, looseness can cause damage such as: fatigue and wear in equipment mounts and further bearing wear. It can become very dangerous and destructive if a vibrating component is either loosely attached to its mounts, or has loose bearings.

Our experienced machine vibration analysts deliver services for a wide range of industries and applications, including: routine machinery surveys, commissioning, troubleshooting, verification, and database setup and support.

  • Misalignment/shaft runout

A common cause of machine vibration is when the machine shafts that are out of line. Misalignment is a root cause of many machine breakdowns, bearing failures, and damaged seals, shafts and couplings. In fact, it is widely believed that over 50% of machine failures are due to misalignment.

Misalignment does not have one single cause but can be a combination of causes. It can happen:

  • By developing over time (wear)
  • During the assembly process
  • Not considering thermal expansion during the alignment process
  • Not being reassembled properly after maintenance
  • Because of shifting components (structural issues)

Not practicing precision alignment will cause premature wear and tear of components, increase unscheduled downtime, increase maintenance (asset life costs) costs due to unexpected repairs—or more expensive, replacement of parts.

RMS provide Motion Amplification Services for a wide range of Industries and applications, including: vibration verification, commissioning, troubleshooting, R&D and root cause analysis.

Why it’s necessary to treat for vibration problems

As we have already mentioned, vibration can create problems that are both time consuming and expensive. For example: vibration consumes excess power, forces equipment to be taken out of service for unscheduled downtime, and expedited machine wear increasing overall asset life costs.

There are also secondary safety issues to consider as well as reduced operational uptime.

Measuring and analysing vibration can provide the asset owners with an indication of a machine’s health condition, and hence the reliability. When this data is analysed correctly it can help with preventive and reactive maintenance actions.

It can improve preventive maintenance by enabling the maintenance team stay ahead of potential problems. It can help with corrective maintenance to ensure that everything which needs repairing—or replacing—is done the first time so there are no unpleasant surprises later on.

Technicians need to be able to understand the difference between abnormal and normal vibration in machine components. With this understanding and the right tools, a technician can reliably, effectively, and quickly find the machine vibration-related issue. And then determine whether or not the component(s) can be repaired, serviced, or if they need to be replaced.

Flue Gas Fan Bearing 2

Corrective methods for machine vibration problems

When it comes to machine vibration problems, the good news is that practically all issues can be corrected in place. That is, of course, provided the vibration-related issues are found early enough.

There are few ways to correctly treat machine vibration problems, these include:

  • Precision balancing
  • Bearing replacement
  • Identifying any additional bad parts and having them sourced then replaced.
  • Precision Alignment
  • Precision Lubrication. That is, ensuring the correct lubricant win the correct volume at the correct time.
  • Dissemble, inspect visually, clean, and then reassemble, this can help to fix some of the more elusive problems. (Be aware of introducing new defects due to human error on intrusive maintenance like this.)
  • Stiffening and mass loading to reduce measured vibration. This should lower motion, however, it will increase local stresses on the bearings if the cause of the vibration is not eliminated. And this will cause bearings to wear at a faster rate.

On a final note, some machines do have excessive vibrating. In these case, and where the machine function is still being fulfilled and there is no deterioration, it may not be worth doing anything. That is, provided that the machine is carrying out its primary function with no apparent anomalies. If the vibration amplitude is stable, then in most cases it’s usually safe for the machine to continue operating. The advantage of this is that it will avoid additional downtime and the unnecessary cost of repairs.

As long as you are monitoring and assessing your machinery with vibration analysis, then you should be able to plan, operate your machines for longer with less wear and tear, as well as reducing the risk of machine failure.

Through active listening we get to understand the problem before talking about solutions. When the problem is understood we recommend possible ways to improve condition through the use of vibration analysis. The AMS 2140 from Emerson is once such technical solution.


If you have any questions about the role of vibration analysis in maintenance and how Reliability Maintenance Solutions can help you, please feel free to contact us, or leave a comment below.

FAQs

There are quite a few causes for why machinery may start vibrating, there are four most common reasons: Wear, Unbalance, Looseness, Misalignment/shaft runout.

Technicians need to be able to understand the difference between abnormal and normal vibration in machine components. With this understanding and the right tools, a technician can reliably, effectively, and quickly find the vibration-related issue.

Precision balancing, Bearing replacement, Precision Alignment, Precision Lubrication, Dissemble – reassemble, Stiffening and mass loading.

Infrared Thermal Imaging is useful across many industrial sectors

Hi! I’m Craig Smith, a Reliability Engineer at RMS. Over the past few years I’ve been using Infrared Thermal Imaging technology to great affect, helping customers diagnose and repair maintenance issues with higher degrees of accuracy and speed.

This article is based on a planned electrical maintenance survey of panels and distribution boards looking for any irregularities. This consists of cables, cable connections, breakers, inverters and control boards.

Our Infrared Thermography service is a predictive maintenance inspection technique that is widely-recognized and an effective non-destructive (NDT) testing tool used often to check electrical and mechanical systems, buildings, roofs and facilities.

Traditional methods of detection

The traditional method for identifying an electrical connection or component problem is the use of an infrared camera when it is under load. However, there is misunderstanding about how to establish the condition of the connection once a thermal anomaly has been found.

Historical methods of Infrared Thermal Imaging have applied the use of temperature, or temperature rise, using the infrared camera, as an indicator of the defect severity. Infrared, however, only identifies surface temperature rather than internal interface temperature.

The value of Thermography is being able to identify that a thermal anomaly exists

While thermography can identify a connection problem through the thermal pattern, the connector surface temperature can be a poor indicator of the nature of the problem or its severity.

How do Thermal Imaging cameras work?

The A0404B1 Infrared Tachometer is recommended for indoor/outdoor use. When used with Emerson’s Machinery Health Analyzers, the phototachs provide a tach reference signal for applications that include measurement of turning speed, synchronous time averaging, machinery balancing, phase tracking, and coastdown/startup analysis.

Where can Infrared help technicians?

Now that we’ve briefly explained the importance of Infrared Thermal Imaging, let’s look at exactly how thermography helps in maintenance.

Key components that thermographic analysis can detect problems with include, but not limited to:

  • Misalignment
  • Bearing health
  • Steam/Water Leaks
  • Turbine machinery
  • Bent shafts
  • Solar panels
  • Moisture
  • Loose bolts, mounts, fasteners, etc.
  • Electrical issues
  • Process flow issues

Top tips when taking a thermal image

  • Understand the surrounding parameters:
    • shooting an image with sunlight or a reflective background (inside panels) will give you bad data
    • also if you are in a panel room and the AC is on
  • Stand at 45* to the object of interest and use multiple angles if possible
  • Adjusting the Emmissivity and Reflected temperature accordingly is a must, or you will get bad data
  • Using a known source of black body:
    • carry electricians’ tape with you and put a piece on the object if safe to do so
  • Don’t ignore small temperature differences:
    • if you are looking at two objects close together one may be quite a lot hotter than it appears on the image
  • Focus on the object and thermally tune the camera to suit using the temperature adjustment

Problem awareness

  • Connections problems occur when fitting lock screws that are under-torqued or Over-torqued
  • Incorrect cable sizing for breaker etc, wrong size lug connections or not lug at all
  • Cable insulation not cut back enough
  • Poor soldered joints.
  • Excessive vibration in the area,
  • Process patterns with stop start or VSD motors
  • Environment issues such as heat or steam, corrosives
  • Always have a good scope of the area you are working in and a good visual of what you are looking at

Recent images explained

The CAT I Vibration Analysis course includes a topic on Thermography. The course is designed for reliability engineers, PdM program managers, and other maintenance staff who would like to understand condition monitoring with a core focus on vibration analysis.

If you have any questions about the role of thermal imaging in maintenance and how Reliability Maintenance Solutions can help you, please feel free to contact us, or leave a comment below.

FAQs

Historical methods of Infrared Thermal Imaging have applied the use of temperature, or temperature rise, using the infrared camera, as an indicator of the defect severity. Infrared, however, only identifies surface temperature rather than internal interface temperature.

Key components that thermographic analysis can detect problems with include, but not limited to: Misalignment, Bearing health, Steam/Water Leaks, Turbine machinery, Bent shafts, Solar panels, Moisture, Loose bolts, mounts, fasteners, etc., Electrical issues, Process flow issues.

Don’t ignore small temperature differences. If you are looking at two objects close together one may be quite a lot hotter than it appears on the image.

Vibration Analysis in Maintenance

Can your technicians make the replace-or-repair decision?

If you engage in maintenance practices, you will want to ensure your technicians can make the replace-or-repair decision before complete system failure of key components takes place. The easiest way to manage this risk is with vibration analysis.

Vibration analysis allows you to detect early signs of machine failure/deterioration. This allows your technicians to replace or repair machinery before catastrophic system functional failure takes place. Read more

Poor bearing lubrication identified and immediately remedied

Here is a great example from James Sylvester of how visually helpful the new Emerson 2140 PeakVue Plus is while working on site.

On a recent survey of a critical 110KW blower motor we noticed the PeakVue levels had increased. While at the machine we quickly ran the PeakVue plus and this highlighted the issue as a poor lubrication condition.

Instead of writing this in the report then living in hope the motor is correctly greased, we showed this at the machine to the site fitter and we were immediately permitted to lubricate the bearings and the levels reduced. Read more

Motion Amplification Webinar

Implementing an Industry 4.0 Maintenance Technology

30 September 2020: 10:30am – 11.45am GMT

maintec logo

Maintec (Nineteen Group)
Reliability Maintenance Solutions Ltd

Organisers: Jos Diamond, Verity Noon and Maggie Law
Host: Keith Gallant (Reliability Consultant and Technology Manager at RMS Ltd)
Speakers: Stuart Walker (Director of RMS Ltd), Jeff Hay (CEO of RDI Technologies)
Guests: Paul Phelan (Reliability Engineer at MSD Biologics)  & Phil Renshaw (Engineering Manager at Vertellus) Read more

Flue Gas Recycle Fan: Introduction

The Flue Gas Recycle Fan is part of the COGA unit. The fan increases the efficiency of the COGA unit by recycling a proportion of the incinerated gases from the COGA stack. The fan is critical in sustaining high rates of operation on the plant, catastrophic failure of this fan would result in a COGA unit shut down. This would increase the emissions to the atmosphere and heavy fines could be imposed by the Environment Agency. Read more

Dynamic Vibration Absorber

BONUS: This is the 6th and final (free) case study in the series on Enhanced System Reliability.

In this sixth case study from his book “Enhancing System Reliability Through Vibration Technology”, James Sylvester from JPS Reliability and an Reliability Training Institute Trainer, shows how the use of Dynamic Vibration Absorbers can effectively reduce vibration levels. This case study covers a 2-year project period from initial root cause diagnosis to designing, trialing, and implementing an innovative cost-effective solution. Read more

23RPM Defect on a 4 Point Contact Bearing

This was to be the final of the five case studies on Enhanced System Reliability by James Sylvester. But, following on from feedback we will have one more case study next week, this will be an extra long project case study!

In this fifth case study from his book “Enhancing System Reliability Through Vibration Technology”, James Sylvester from JPS Reliability and an Reliability Training Institute Trainer, demonstrates vibration analysis of a slow rotational 4 Point Contact Bearing, with a 23RPM Defect. This is to remind us that correct database set up, and Time Waveform Analysis is so important in slow rotational bearings. Read more

Vibrating Screen Gearbox Bearing Defect

This is the fourth of five video case studies on Enhanced System Reliability by James Sylvester.

In this fourth case study from his book “Enhancing System Reliability Through Vibration Technology”, James Sylvester from JPS Reliability and an Reliability Training Institute Trainer, shows how it’s possible to diagnose faults on a vibrating screen. We demonstrate that by measuring the correct vibration parameters you can resolve defects in harsh applications, even an inner raceway defect on a vibrating screen. Read more

Variable Frequency Drive Deterioration

This is the third of five video case studies on Enhanced System Reliability by James Sylvester.

In this third case study from his book “Enhancing System Reliability Through Vibration Technology”, James Sylvester from JPS Reliability and an Reliability Training Institute Trainer, shows how analyzing vibration and thermal data can diagnose electrical drive faults. Read more

Standby Fan Motor Bearing Defect

This is the second of five video case studies on Enhanced System Reliability by James Sylvester.

In this case study from his book “Enhancing System Reliability Through Vibration Technology”, James Sylvester from JPS Reliability and an Reliability Training Institute Trainer, shows how analyzing bearing damage can lead to the root cause of the problem. Read more

Electrical Vibration Problem

This is the first of five video case studies on Enhanced System Reliability by James Sylvester.

In this first case study James shows how vibration analysis can be used to diagnose electrical vibration problems. In this case a VFD driven Motor. Over the next few weeks James is going to share a selection of interesting vibration analysis case studies. Enjoy, and please share if you found it useful – thanks. Read more

4th May 2020

Company News

RMS Reliability Training Institute are pleased to announce and welcome James Sylvester as a partner into the RMS Training Team. Read more

20 December 2020

Service announcement

We are optimistic that scheduled Public Training courses in early 2021 will run in the booked locations. We will update the course page should situations change. Our team continues to remain vigilant of the situation and is responding rapidly as conditions evolve. We will provide ongoing updates via Social Media and our Website to ensure you have clarity of our capabilities to support you. We are continuing to follow the UK Government’s health guidelines. Read more

As part of the Innovate UK fund, over the past 2 years RMS have been involved in an ‘Intelligent Wireless Vibration System’ collaboration between the Building Research Establishment (BRE), Cybula, Griffiths Associates and Skanska. The project called REAM (Enabling remote built environment asset management using embedded intelligence) is tasked with enabling low-cost embedded intelligence within the Facilities Management (FM) market. Read more

Arlanxeo Performance Elastomers, Belgium, win a BEMAS Asset Performance Award; from all at RMS Reliability, many congratulations on this well-deserved achievement.

In the category ‘Best Improvement in Maintenance & Asset Management’, Christophe Van de Maele and Kristof Van Den Berghe of Arlanxeo were allowed to take the trophy home. The four case examples in which they used their new motion amplification camera received great acclaim. Read more