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A Case Study: Motion Amplification Analysis of a Drum Drive Gearbox

A manufacturing plant located in WA recently encountered a significant issue related to a critical drum drive gearbox. The Asset Management and Reliability Team noticed excessive vibrations and sought to identify the root cause of this problem. To address this issue, the Iris M™ Motion Amplification® technology was utilised. This case study outlines how Motion Amplification® technology successfully captured, quantified, and qualified the operational vibration characteristics and identified the root cause of the problem.

Problem Identification:

The manufacturing plant initially detected unacceptable levels of vibration in the drum drive gearbox of their machinery, which they had yet to identify. This vibration had the potential to disrupt operations and, if left unaddressed, could lead to costly equipment damage.

Motion Amplification Analysis:

Upon implementing Iris M™ Motion Amplification® technology, the plant’s Asset Management and Reliability Team conducted real-time data analysis, revealing several crucial findings:

  1. Vibration Frequencies: The analysis showed that the majority of the vibration in the drum drive train occurred at three distinct frequencies:
    • Motor running speed: 25.76Hz
    • Pinion gearmesh frequency: 7.69Hz
    • 2x pinion gearmesh frequency: 15.38Hz

The presence of the 2x pinion gearmesh frequency indicated a classic symptom of gear misalignment and uneven wear across the gear teeth.

  1. Phase Difference: There was a noticeable phase difference between the motor and gearbox input, which is a typical indicator of offset misalignment across the coupling.
  2. Vertical Orientation: The vibration analysis also revealed that the vertical orientation of the inner side of the drum drive gearbox’s base frame exhibited higher levels of vibration compared to the outer side.

Recommendations:

Based on the observations and analysis using the Motion Amplification® technology, the following recommendations were made to address the identified issues:

  1. Pinion Inspection and Realignment: Given the presence of gear misalignment and uneven wear across the gear teeth, it was recommended that the pinion be inspected thoroughly. Any misalignment should be corrected and worn gear components should be replaced.
  2. Torque Arm Connection Inspection: The connection between the torque arm and the base frame should be inspected for any signs of damage or misalignment. Any issues found in this area should be promptly addressed.
  3. Motor-to-Gearbox Realignment: To resolve the phase difference identified between the motor and gearbox input, realignment of the motor to the gearbox is necessary. Proper alignment will ensure that power is transmitted efficiently and reduce unnecessary stress on the machinery.

The implementation of Iris M™ Motion Amplification® technology proved to be instrumental in diagnosing and identifying the root causes of unacceptable vibrations in the drum drive gearbox. Through this analysis the plant was able to mitigate the vibration complications and prevent potential equipment damage, ensuring the continued smooth operation of their machinery.

 

 

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Techniques for Effective Condition Monitoring of Low-Speed Machines

Condition monitoring of low-speed machines, operating at speeds typically below 600 RPM, demands a systematic approach due to the inherent challenges that slow speed operation carries. Here we review some of the techniques utilised for successful monitoring of slow-speed machinery.

The unique characteristics of low-speed machines give rise to a series of challenges when establishing a condition monitoring program:

·         Lower frequencies of interest

·         Lower impact amplitudes (vibration signals)

·         High ambient noise

Lower frequencies of interest:

The slower rotational speeds mean that the fault frequencies of interest in condition monitoring (e.g. bearing ball pass frequency) typically occur at much lower-frequencies and vibrations and dynamic signals, complicating the task of identifying anomalies and irregularities.  Lower rotating speeds result in lower amplitudes in the impacts that are often key indicators used in vibration or ultrasound analysis to detect early stage bearing faults.  Slow rotating machines are often found in crushing, milling, grinding and other processes, where there are high levels of ambient noise and vibration. The presence of these external noise sources, lowers the signal-to-noise ratio, making it challenging to extract relevant data.

To tackle the complexities of monitoring low-speed machines, a comprehensive approach integrating various complementary methods is preferred. This multi-pronged strategy enhances data accuracy and dependability, facilitating a thorough understanding of the machine’s health.  Here are the key techniques commonly employed:

1.    Vibration Analysis: Vibration analysis remains a cornerstone technique for low-speed machinery monitoring.  Through the utilisation of high sensitivity sensors, longer time waveforms and advanced signal processing algorithms, low level faults associated with operational abnormalities can be detected. Proper sensor selection- and placement, as well as good data collection parameter configuration, are pivotal for optimal data acquisition and analysis.

 

2.    Oil Analysis: Lubricating oil analysis serves as a valuable diagnostic tool for slow-speed machines.  By monitoring contamination and wear debris, insights into potential component issues can be gained early.  Regular oil sampling and analysis are critical for the early detection of deterioration.  It is recommended that analytical ferrography or filtergrams be specified as part of the analysis package of slow speed machines as these methods provide more accurate wear particle and contamination information for monitoring slow speed machines.   The latest developments in online oil condition sensors show significant promise for slow speed machine monitoring.

 

3.    Thermography: Thermal imaging is adept at identifying overheating problems and abnormal temperature distributions within machinery. In low-speed machines, where temperature changes might manifest more gradually, thermal imaging helps pinpoint localised heat irregularities or cooling inefficiencies.  It should be noted that thermography is typically a late stage indicator of faults and cannot be relied upon for early detection of developing problems.


4.   Ultrasound Condition Monitoring: Ultrasound monitoring has emerged as a preferred technique for slow-speed machines. Ultrasound waves can detect subtle changes in machinery, such as friction, impacting, cavitation, and leakage. Ultrasound provides a powerful means for optimising lubrication doses in grease lubricated machines. Ultrasound monitoring techniques enhance early fault detection even in low-speed conditions and supports predictive maintenance efforts.

By integrating a spectrum of condition monitoring techniques, maintenance teams can achieve a comprehensive understanding of machine health. These preferred methods enable the efficient and accurate monitoring of slow-speed machinery, facilitating timely interventions and assisting in ensuring the equipment reaches its intended lifespan. 

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CBM+RELIABILITY CONNECT® Conference – Nov 8th – 10th

Join us in person for the CBM+RELIABILITY CONNECT® Live Training Conference in Melbourne, 8-10 November 2022.

We are pleased to announce that Sven Fleischer & Roman Megela Gazdova from Easy-Laser, will be hosting a hands-on workshop entitled LASER SHAFT ALIGNMENT BEST PRACTICES.” In this workshop you will learn what is required for optimal machine installation and take part in practical exercises and demonstrations including:

  • Laser shaft alignment principles, procedures, and best practice.
  • Measuring machine base flatness and level.
  • Understanding dynamic & static forces like pipe strain, thermal growth, and soft foot.
  • Overcoming fault conditions during the alignment process such as bolt-bound & soft foot conditions, and more!

Reliable machine operation starts with correct machine installation and alignment!

The full event will host:

  • 7 hands-on workshops featuring a variety of industry technologies.
  • Renowned industry expert, Steve Potts, will present an insightful Keynote.
  • 15+ interactive Condition Monitoring & Reliability improvement learning sessions, including real-life case studies along with technical presentations featuring the latest industry research.
  • Exclusive networking opportunities and exhibitions by industry-leading companies.

View the full schedule of events here

In-person learning and networking opportunities have been few and far between during these times. The conference organizers and venue have been working to provide you with the opportunity to learn and network in a safe environment, with industry thought leaders.

We are excited to get the industry back together and look forward to connecting with you at the event.

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Troubleshooting a 4-20mA Accelerometer System

Cal Cert Example

Fig.1

The first thing to check is that the wiring is carried out and in accordance with the calibration sheet provided with the sensor. Check polarity of the voltage power supply.

Fig.2

The next thing to check is that the accelerometer is being powered correctly. Check the cable datasheet to see which two pins to be checking the voltage across. The voltage should be somewhere between 15 and 30 volts. Many systems would typically be 24volts. If the accelerometer has an integral cable then a point along the signal path needs to be checked. The closest point to the accelerometer should be sought to check the voltage. This ensures that a check for discontinuity in the wiring is taken with as much of the signal path being checked as possible.

Fig.3

If the accelerometer is seeing the correct voltage then the next check is to see if the accelerometer is generating a current that is at least 4 mA . To do this the multi-meter needs to be in series with the accelerometer. The circuit wiring needs to be disconnected at some point along the signal circuit and the meter inserted. If the machine on which the accelerometer is mounted is off you would expect 4mA. (No vibration condition). If the machine is running and vibration is being generated you would expect to see anywhere from 4 to 20 mA depending on the level of machine vibration. If you have 15-30V of power and you are seeing less than 4mA then the accelerometer is defective. If you are seeing greater than 20mA then the vibration levels are saturating the sensor or the sensor is defective.

Fig.4

If at least 4mA of signal is being generated then the accelerometer is most likely functioning correctly. If the accelerometer is showing more than 20mA and the machine is running then the machine vibration might be saturating the accelerometer and a lower sensitivity sensor is required. To check for this disconnect the sensor and repeatedly hit it with a light object. This should cause the mA current to increase. The Hansford Sensors 4-20mA sensors have a 5 second averaging circuit so ensure the light tapping of the sensor is repeated for at least 10 seconds to register above 4mA. If the accelerometer remains at 20mA or above despite being disconnected from the vibration then the accelerometer is likely defective.

 

If you have any questions, please contact us at sales@gvsensors.com.au or view our product range here

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Complementary Technology – Misalignment

Visualise, Measure, Troubleshoot and Correct machinery misalignment with Motion Amplification® and Easy Laser® Reliability Products from GVS.

 

Motion Amplification® and Easy-Laser® are fantastic complementary tools for visualising misalignment, measuring thermal growth, and correcting misalignment making Proactive (Precision) Reliability Maintenance even more achievable.

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The way you install your rotating machinery is the way it will perform!

Because of my many years of experience in the field of installation and maintenance of rotating equipment I can say that installation is a fundamental thing. But why is this phase so important?

Well, because the installation has direct impact on the machinery, and it will determine operating conditions, performance, and life cycle cost. Basically, the way you install your rotating equipment is the way it will perform. And personally, I always ask myself why companies buy million-dollar pieces of equipment and let inexperienced installers do the installation. Then, they spend another million dollars in condition monitoring watching them fail.

Don’t get me wrong; condition monitoring is extremely important to understand what is happening to the machines and detect an early failure. But the fact is that most of the failures occur due to poor installation and design. Here, let’s focus on the installation phase of rotating machinery.

What do we expect from our machinery?
  • Reliable operation – We expect our rotating equipment to deliver its intended purpose or service without failure.
  • High performance – We expect our equipment to perform as per design.
  • Long service life – If our equipment has been designed for 20 or 30 years of operation, that is what we want to achieve.
  • Low maintenance cost – We expect not to spend any additional money after the investment has been made.
Responsibilities towards the installation

Communication, Procedures, and Integrity. These are responsibilities which are so important in the installation phase. Let me explain:

Communication
It is a must to assure proper communication among the Design, Engineering, and Installation teams. We know there are constant challenges to keep the installation work to be on time and within specifications. The teams must have constant communication to be able to solve any difficulties or changes. In the real world not everything fits as it fits on the drawings. I think many of you have experienced this, right?

Procedures
Installation procedures must be created according to design specifications and every member of the team must be familiar with them. Depending on which industry, the procedures will differ from each other. It is not the same thing to perform installation on the nuclear plant compared to pharmaceutical industry. There should always be a reference to which specific standard belong to the site where the installation is taking place. API Recommended Practices for Machinery Installation and Installation Design (API 686) are the perfect foundation to start with.

Integrity
Integrity is an important part of the installation phase and it starts with Safety. Everyone who participates in the installation must go through safety training. Specific trainings must be performed such as working in heights, confined spaces, fire protection or chemicals handling. Breaking the safety rules will put the project behind the schedule therefore it is very important to follow them.

Always do things in the right order

The installation of rotating equipment must follow a certain order. The order of the installation procedure is designed to always start from the base. Foundations are the cornerstone of the entire installation. They are designed to hold rotating machinery and transfer and dissipate stresses and dynamic forces produced by pulsations and processes. Therefore, special attention must be paid to the foundations. They must be flat, coplanar, and levelled. If we skip the order of the installation procedures, we will not be able to complete further steps and not achieve reliable operation of our rotating equipment.

Finally, all the work must be properly documented during the process by creating digital reports to be able to review and compare the values and data. This is important for the references because further work will depend on the results.

Author

Roman Megela
Senior Reliability Engineer
Easy-Laser AB  

This article was originally published in MaintWorld Magazine

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How to select the right vibration sensor

With so many different types, shapes and sizes to choose from, selecting the right vibration sensors (otherwise known as accelerometers) for your operations can be a challenging task. It is, however, essential. To ensure you specify correctly, there is a number of important factors you need to consider.

Vibration range and sensitivity – The range of vibration varies greatly from operation to operation. You should always specify vibration sensors to measure the maximum vibration range of your specific application. In a standard application (80g range), the sensitivity of a typical vibration sensor is 100mV/g, while in low vibration applications (16g) the sensitivity is 500mV/G.

Vibration frequency – Knowing the frequency span you need to measure is as important as knowing the vibration range. The frequency spans are dictated by the fault frequencies of the fastest-turning component in the machinery being monitored. The frequency span of a slow turning ball mill, for example, will be narrower than that of a high speed fan.

Environmental temperature – After poor and incorrect mounting, the greatest threat to the performance of vibration sensors is the environment. High temperatures can affect the operation of the electronics. However, charge-mode accelerometers are specially designed to work in applications with very high temperatures.

Contact with chemicals or debris – This can reduce the reliability of results and should therefore be considered carefully. To ensure performance and results are unaffected by exposure to chemicals or debris, accelerometers with corrosion and chemical resistant stainless steel bodies should be specified.

Hazardous atmospheres – Hazardous environments are those that contain flammable gasses or vapours, combustible dusts, or ignitable fibres, where even the tiniest spark could cause a fire or explosion. To protect people, machinery and productivity, you need intrinsically safe accelerometers, which are specifically designed for use in hazardous areas. They deliver the same level of performance as their non-intrinsically safe counterparts, but do so by using a lower level of energy.

Immersion in liquid – The average accelerometer isn’t constructed to be waterproof. If your application requires accelerometers to be exposed to liquid, the solution is to specify vibration sensors with integral polyurethane cables. This prevents liquid infiltrating the accelerometer and affecting the electronics – whether the sensor is at minimum sprayed with water or even completely submerged in liquid on a permanent basis.

Exit and profile – The exit and profile of a vibration sensor has minimal impact on performance, but if not considered can become a frustration for those responsible for maintenance. Depending on where the vibration sensor is located, you can choose between a top exit, side exit or low profile connection to allow maintenance engineers easy, safe access.

By taking these factors into consideration you can make the right choice in vibration sensor specification for the requirements of the average application or an industry specific use. If you need further assistance or require advice on special applications, GVS is here to help and can assist you in selecting the ideal vibration sensor. Get in touch today, or view our full range of vibration sensors, cables and accessories. 

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How to deal with Thermal Growth

All rotating machinery is subjected to thermal exposure. The machines will react differently depending on temperature and material, either by expanding or shrinking. And that is a fact. Thermal growth is a serious thing when you think about it.

All rotating machinery is installed in trains. Trains mean there is a driver, the motor, and driven, which can be a pump, blower, compressor, or any other type of process machine. During the installation of rotating machinery, precision shaft alignment is performed. The shaft alignment will ensure that both shafts (driver and driven) are collinear. Collinear means that both rotational centerlines are positioned as if they were one.

The effect of heat on driver vs. driven

When the machines are started, the driver and driven heat up in very different ways. A compressor in a hot environment will quickly increase in temperature due to friction of its internal rotating parts, and compression of the media will generate and add more heat. Comparing to the driver, which can be an electrical motor, the situation is very different. The temperature will increase to a certain level and then remain the same — two machines with two different behaviors. 

So, what happens when one of them increases its temperature relative to the other? It’s simple; the machine will start expanding. And when the machine expands, it will grow in all directions, move its rotational center out of collinearity and cause misalignment. But not only misalignment. Since there is a change in the machine geometry, pipe strain might also add more stress to the housing

 

Take thermal growth into account from the start

There are so many consequences of thermal growth in rotating equipment. Misalignment will, for example, also result in a bent shaft. Bent shaft will result in improper distribution of forces in the bearing, which will lead to failure of the lubrication. Therefore, we must be able to anticipate thermal growth by using available information from the OEM, or by performing the calculation by ourselves. So how do we do that? 

The key is to identify how much growth to expect. This number must be used when performing the shaft alignment to “intentionally misalign” the machines prior to start. Let us use the compressor as an example again. If we assume that the compressor will operate at a higher temperature than the motor, when aligning, we must place the compressor below the rotational centerline of the motor. How much below will be determined by the expected thermal expansion growth of the material.

Final test run

When the machine is aligned with the thermal growth considered, it must run and operate until it reaches its full operating condition. Then it must be stopped, and the shaft alignment verified. This is our test run of the machine, to confirm a proper and reliable installation, and to achieve full operational life. We want to test before we go to full production to ensure our thermal expansion calculation was correct. 

Think about aircraft maintenance. When there is an aircraft engine replacement, the pilots perform test flights until it can be confirmed that everything is operating as it should. And you don’t want to be on the plane knowing nobody performed the test run, do you?

Roman Megela Gazdova
Senior Reliability Engineer, Easy-Laser AB

 

So now you know the importance of thermal growth, how are you going to factor this in? 

No problem with Easy-Laser’s XT app.

Simply enter in the offset & angle values and the program will automatically calculate thermal expansion of the machine.

Contact GVS to learn more.

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Reliability Journey: From Mechanical Technician to Ultrasound Inspector

Ultrasound is considered to be the most diverse condition monitoring technology on the market covering both air-borne & structure-borne applications.

AND

The first signs of change in the operating condition of an asset are usually indicated in the ultrasound frequencies.

SO

Ultrasound should be your first line of defence for asset reliability.

SDT’s NEW ‘Live Online Level One’ (LOLO) is a comprehensive course which walks you through the basics of Ultrasound and how this can be applied across the 8 application pillars. It exceeds ISO 18436-8 requirements and is a combination of 45+ years of technical and real-world experience. Sound daunting? Don’t worry.

SDT have broken this up into 16 x 2 hour virtual sessions over an 8 week period straight to your desktop, tablet or other mobile device. All available for On-Demand playback giving you the flexibility to learn at your own pace. Full course details can be seen here.

Don’t just take our word for it. John Garrison, recent LOLO graduate recently shared his experience and how he used the knowledge he gained to perform ultrasound inspection and analysis on equipment in his facility. Download the full testimonial/case study below.

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LUBExpert Case Study: 70% of bearings are still OVER lubricated

Bearings need grease, however… 

It’s a common misconception that if a little grease is good then a lot means better. WRONG!

Too much grease will overheat a bearing causing separation of the oil from its thickener and will begin to run out of the bearing. This can set off a chain reaction resulting in lack of lubrication & hardening of the thickener which left unchecked will cause major issues.

Many studies have shown that only 33% of the open space within a bearing needs to be filled to achieve optimum friction reduction. 

33%? How do you that?

ALS Global (Australia’s largest condition monitoring service provider) conducted an independent study over an 18 month period using the LUBExpert. The device was used across a large volume of grease lubricated bearings which were historically replenished using fixed calculated / time based rates.

Find out why ALS now choose the LUBExpert as their preferred method of lubrication. Download the full case study below.

 

How are you lubricating your bearings?

 

Save Time. Save Grease. Save Bearings. Use LUBExpert and ‘Grease Bearings Right’.