Which is the Best Bearing Fault Detection Technique?

December 5, 2017

Condition Monitoring Expert Tip #5 by Mobius Institute

Now this is a tricky question to answer… We have a few contenders: high frequency vibration analysis, regular vibration analysis, ultrasound, oil analysis, wear particle analysis, and infrared analysis. Let’s start by ruling a few of them out.

Infrared analysis is used to detect heat in a bearing, which is a late stage fault condition, so that’s not your best option. Regular oil analysis can detect the presence of the wear metals within the bearing, but wear particle analysis is a better tool for that. Regular vibration analysis (i.e. velocity spectra) provide very clear indications of bearing faults, however the high-frequency detection techniques provide an earlier warning. That leaves high-frequency vibration analysis, ultrasound, and wear particle analysis.

Ultrasound is easiest to use. Push the probe against the bearing and listen carefully and you will hear if the bearing is in distress. (You can also record and analyze a waveform, but now you may as well be performing vibration analysis). Many would argue that high-frequency vibration analysis (such as enveloping, PeakVue, shock pulse, and others) provide a clearer indication of the nature and the severity of the fault. But it does require more training and potentially a more expensive system to perform the collection and analysis.

And that leaves wear particle analysis. Let’s just say that if you own critical gearboxes, you absolutely must perform wear particle analysis. Performed correctly, you will detect the first signs of wear, and complex gearboxes provide a greater challenge for the vibration analyst and the ultrasound tools.

Although I haven’t really answered the question, I am hoping to have put you in a position to make the right decision for your situation.

Thank you Mobius Institute for this valuable tip!

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Guidelines for Proper Belt Installation including Sheave Pulley Alignment

November 28, 2017

Belts are a critical part of the design and function of belt-driven equipment. The majority of belts never reach their intended design life due to improper selection, storage and installation. Unfortunately, this results in compromised equipment operation, lost capacity and increased costs. Do not condemn your equipment to death through improper belt installation practices. Below are some guidelines to help your facility ensure belt-driven equipment reliability:

  • Follow all site specific safety procedures.
  • The same basic installation steps are required for both synchronous and V-belts.
  • Loosen motor mounting bolts or adjustment screws.
  • Move the motor until the belt to be replaced is slack and can be removed easily without prying or any other means of force. Prying off a belt or chain can damage a sheave or sprocket and increase the risk of injury. Never use a screw driver to remove belts, because this may damage belt cords, sheaves and sprockets.
  • After removal, inspect old belt for unusual wear that may indicate problems with design or maintenance issues.
  • Visually inspect and replace sheaves or sprockets that have excessive wear, nicks, rust, pits or are bent.  Grooves that appear “shiny” or polished could indicate heavy wear and should not be ignored.  Never sand or scrape groves.  Doing so will insert points of wear leading to premature belt or sheave failure.
  • Sheave gauges should be used to measure for excessive wear and determine if sheave replacement is necessary.  Total wear should not exceed 1/32 in or 0.8 mm.
  • Sheaves and sprockets should be checked for proper alignment.  A laser alignment tool is the recommended means.  Most major belt manufacturers recommend a nominal tolerance of 0.5 degrees.  However, better alignment tolerances should be achieved if possible.  The table below can be used to determine proper alignment.For maximum resolution, always mount the laser alignment tool on the smaller sheave and the targets on the larger sheave.  Ensure that the alignment tool being used can indicate misalignment in all three degrees of freedom (axial offset, horizontal angularity and twist angle).

Note 1: Check and correct any run out conditions prior to belt installation.  Tighten bolts in the proper sequence to prevent axial run out.

Replace all belts on multiple belt drives with new belts from the same manufacturer. Never replace a single belt or a portion of a multiple belt drive. Mixing old and new belts will create unevenly shared loading and lead to premature belt failure and/or sheave wear.

  • When installing the new belt, ensure that enough clearance is available to slip the new belt(s) over the sheave or sprocket. Never pry or use force to install the belt(s). Never use a screw driver to roll belts into position, because this may damage belt cords, sheaves and sprockets.
  • Adjust the motor base until the belts are tight. Motor should be checked for soft foot conditions using a feeler guage or other suitable means and corrections made if required. No reading of soft foot should be greater than 0.002 inches or 0.05 mm.
  • Use a tension gauge or sonic tension meter until the correct tension is measured according to specifications.
  • Rotate the belt drive by hand a few revolutions and re-check and adjust belt tension as necessary.
  • Re-check the sheave or sprocket alignment and re-adjust if necessary.
  • Secure motor mounting bolts to the correct torque specifications.
  • Replace equipment guards and follow any other site specific safety requirements to return the equipment to operation.
  • Upon equipment startup listen and visually inspect for any unusual vibration, noise or heat. Other corrective actions may be required (lubrication, tension adjustment, etc.) to ensure equipment is ready for proper operation.

Note 2: Contact the belt manufacturer and provide the drive information to receive the most accurate tension information for the required operating loads.  Belt tension charts may specify more tension than is required by the application.  The proper tension for the belt is the minimum tension required to prevent the belt from slipping at maximum load.  A good guideline in the absence of any other information is to use a spring scale, and press down on the belt in the approximate center of its span (on the tight side), to deflect the belt 1/64″ per inch of span length and observe the force required to do so. If you are not sure of the belt span length you may also use the center-to-center distance of the pulleys, which will be similar. Tension the belts until the force required for this deflection equals the belt manufacturer’s maximum recommended force values for the specific belts you are using.

Note 3: Belts should not squeal on startup when adjusted to proper tension.  This can be an indication that the drive is not proper for the application. 

Note 4: A run-in procedure may be required for V-belt drives or other installations to ensure optimal belt life and equipment reliability.  It is recommended to check and adjust belt tension under full load after 20 minutes, 24 hours and 48 hours of operation to properly seat the belts in the sheave grooves.  Consult belt manufacturer and engineering specifications to determine if a run-in period is required and length of time.

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7 Belt Storage Tips for Better Equipment Performance and Long-Lasting Belt Life

November 21, 2017

Unfortunately, proper storage of belts is often overlooked.  I visit a lot of plants and almost always see equipment belts improperly stored to the detriment of optimal reliability.   Ensuring that the belts used in your equipment are properly stored will result in:

  • Fewer failures upon startup
  • Longer belt service life
  • Better equipment performance
  • Improved safety
  • Preservation of belt warranty coverage

Below are some belt storage tips to help ensure that your equipment functions as healthily and long as possible:

  1. Belts should be stored in a cool and dry environment with no direct sunlight.  Storage temperature should be below 85°F/29.5°C with a relative humidity no higher than 70%. Belt performance is reduced by 50% for every 15°F / 9.5°C above 115°F / 46°C.
  2. Do not store belts in areas exposed to:
    • Airborne chemicals
    • Heat sources
    • Direct sunlight
    • Airflow from heat sources
    • Transformers, refrigerators, motors or other sources that create ozone
  3. It is not recommended to store belts on the floor. If floor storage is required, the belts should be stored in a protective container and never exposed to foot traffic.
  4. Never twist, bend or crimp belts during storage and handling. Doing so will damage them.
  5. Do not hang belts from pegs as they will distort over time. Do not store belts under any state of tension.
  6. V-belts may be stored by hanging on a wall rack only if hung on a saddle with a diameter at least as large as the minimum diameter sheave recommended for the belt cross section. If coiling a V-belt for storage, consult the supplier for limits. It is always best to store belts flat on a shelf.
  7. Store belts in the original box. Stacking of belts on top of each other should be limited. Ensure that the belts on the bottom are not damaged by the weight of the belts on top.
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Precision Maintenance: Why do it? – Alignment and Balancing Procedures

November 14, 2017

As Published by Maintenance Technology Magazine September 2017 issue

If greater reliability and uptime are of any concern to you, then precision maintenance is a key component in achieving it. This means having clear and simple, yet meaningful, procedures in place for the different tasks involved. Two such tasks are precision alignment and balancing. LUDECA’s  5-Step Procedures will help guide your facility and maintenance staff to achieving precision maintenance.

Get your own copy of these 5-Step Procedures:


Download 5-Step Shaft Alignment Procedure


Download 5-Step Balancing Procedure

Why is precision maintenance so important?  The reasons are clear:

  1. Safety
    The alignment and balancing procedures lay out the basic steps required to align and balance machines safely, reducing risk of injury and increasing likelihood of a quality outcome. Checklists simplify the workflow and serve to remind employees of the processes required to consistently and safely perform the precision maintenance task.
  2. Reliability
    Well-aligned and balanced machines run more reliably, with a greatly reduced probability of failure. This allows for better maintenance planning, greatly reduced repair and maintenance expenses, increased uptime and more profits.
  3. Efficiency
    A good alignment procedure ensure that machines are aligned to the proper tolerances for the running condition of the machines, taking into account such things as thermal growth and anticipated positional changes. This ensures that the greatest efficiency is achieved in your running machinery, prolonging their health and reducing power consumption. Studies have shown that well-aligned machines result in a 3% to 10% reduction in power consumption. Noise and heat generation is reduced, producing a safer work environment.
  4. Production Quality
    Good alignment and balancing result in better product quality since vibration is minimized, resulting in a more uniform and higher product quality. Unexpected breakdowns in production machinery may lead to costly waste from scrappage and high restart costs for the production line.
  5. Training & Procedural Consistency
    Once implemented, a procedure ensures all employees involved in the activity face clear and consistent expectations and processes, leading to a better understanding between all staff in the facility. Training expense can be reduced since often only refresher training is required to update understanding of the technology utilized as updates are rolled out. Records should be kept that document employee training.

The next step in precision maintenance and reliability is the Implementation of formal specifications that detail every step in a task from safety to activity process to documentation, to ensure that anyone involved can follow the procedures and guidelines without confusion, and reach the desired outcome for all machinery types in the plant. Such specifications typically take from two to three months to develop and a further two to three months to roll out and fully implement. LUDECA has written a number of these specifications for customers worldwide. Let us help you as well.

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One Condition Monitoring Technology is Not Enough!

November 7, 2017

Condition Monitoring Expert Tip #4 by Mobius Institute

This tip is sponsored by IMVAC (International Machine Vibration Analysis Conference)

There is no doubt that technologies such as vibration analysis, oil analysis, ultrasound and infrared are very powerful. They can tell you a great deal about fault conditions in rotating machinery, electrical systems, and more. But if the criticality warrants it, you will be in a much stronger position if you have multiple technologies indicating that a fault condition exists rather than relying on just one.

For example, if vibration analysis indicates there is a problem in a gearbox, oil analysis can confirm the fault with the presence of wear particles. In the case of vibration analysis, you can utilize high frequency analysis, spectrum analysis, time waveform analysis, and phase analysis to enable you to validate your diagnosis.

There can be a great deal at stake when you make a diagnostic call on a piece of equipment. More so if it is critical equipment. At the very least, a false diagnosis may lead to equipment failure (if you miss the fault condition) or it can lead to unnecessary work and downtime. What’s more, your reputation is at stake. Sadly, people often forget when you make the right call, but it can take years for people to forget when you make the wrong call.

Thanks Mobius Institute for sharing such valuable information with us!

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