While the person in charge of collecting vibration data is actually collecting the data, they should watch the data “live” for unusually high amplitudes or discontinuities in the data. This will not increase the data collection time, and if any of these issues are detected, the person can evaluate whether or not the data is “good” or not; if not, the data can be recollected, or if it is “good” then additional data may need to be collected to ensure that proper analysis can be performed on the equipment. Field notes can be made about the machine condition and its status. If the machine condition is determined to require attention, the analyst might need to contact someone at the facility. Remember that sudden increases or decreases are usually a sign of machine problems. Looking at or analyzing the data in the field can give the analyst a good idea of what issues need to be analyzed, thereby reducing the time analyzing data in the office. If not analyzing the data on the spot, one can at least make notes to aid in later analysis.
by Gary James CRL
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!
by Yolanda Lopez
Condition Monitoring Expert Tip #2 by Mobius Institute
This tip is sponsored by IMVAC (International Machine Vibration Analysis Conference)
How do you decide how often measurements should be taken?
Regardless of the condition monitoring technology, you must decide how often measurements will be taken. At one extreme, it could be a permanent monitoring system that takes measurements every split second of every day. At the other extreme, it may be infrared analysis that is performed once a year. But how do you make that decision?
The most common answer we receive is that it is based on the criticality of the equipment. More frequent measurements are taken on the more critical equipment. The next most common answer is that it is based on reliability. If you have been monitoring a machine with vibration analysis every 30 days and have not detected a fault for a year you may decide to test it every 60 days, or 90 days. Now, it is true that you have to decide how best to use your precious time. But the one factor often forgotten is the “PF interval”.
The PF interval, also known as the “lead time to failure”, is the time between when you can detect the fault condition and when the equipment will have “functionally failed” – i.e. it can no longer be used. If we use the right technologies with the correct settings and we take frequent measurements, then we will get the earliest warning, and therefore we have the greatest lead time to act. However, if the PF interval is short, then it is possible that if you have extended the measurement period to 90 days, the equipment may develop a fault and fail before you take the next measurement.
There is a lot more that could be said on this topic but suffice to say that it is essential that you understand the PF interval and continue to monitor equipment so that you take at least two measurements between the time the fault is detectable and when the asset will have functionally failed.
Special thanks to Mobius Institute for allowing us to share this condition monitoring expert tip with you!
by Yolanda Lopez
Purchasing a condition monitoring tool is one step in your journey to implementing a reliability program. Proper training on how to use the new technology, planning the work correctly, ensuring the work is completed on schedule and done so correctly is critical to success. Just as important is understanding the risks associated with your equipment, especially when it fails. A criticality assessment along with failure modes and effects analysis will help you understand those risks and determine where to focus your maintenance activities.
I recently spoke to a plant engineer that had purchased alignment and vibration equipment from LUDECA. He had performed several alignments and collected baseline vibration data. The decision was made to start aligning machines that required maintenance and this was a wise choice to ensure failure modes were not inserted into equipment during routine maintenance activities. Unfortunately, this facility had not performed a criticality assessment on their machinery! It turns out that the plant had a catastrophic failure on a piece of equipment that was vital to the overall production processes of the plant. The first comment made was “why did we have this failure when we recently invested in alignment and vibration equipment?”
You must fully understand the risks to safety, production, environment, and profits that your equipment imposes on your facility. As you can see from the example above, not understanding these factors may lead to continued equipment failures and their undesired consequences. To ensure that you do not continue to experience maintenance failures requires that you fully comprehend the risks that each piece of equipment entails. Had this facility understood the failure modes and the (criticality/risk) impact each machine posed, they would have been able to focus their maintenance efforts where they were most needed to keep the plant efficiently operational.
As part of this endeavor, it is important to apply condition monitoring (vibration analysis and properly targeted alignment, among other things) on the equipment within your plant, because it is extremely difficult to be reliable without doing so. However, you must understand how and where to direct those efforts to ensure that unwanted risks are reduced. Understanding how your equipment can fail (FMEA), the consequences of those failures (RCM or risk assessment), what equipment is most important to keep your plant operational (criticality assessment) are all important to ensure that your maintenance efforts are properly focused. These efforts may avoid the experience this facility had and prevent your plant from experiencing the same unwanted effects.
by Frank Seidenthal CRL
Guest post by Ray DeHerrera, Mechanical Engineer at Pioneer Engineering
Vibration analyst use multiple tools to predict a potential fault in a machine; from transducers to accelerometers, the toolbox for vibration analysts is continually expanding to allow for more comprehensive and accurate data collection and interpretation. One tool that is absolutely important to the data analysis process is knowing how your equipment processes data. Vibration analysts needs to know how results are being derived from multiple calculations within your equipment. This allows for the development an efficient collection history that will produce more accurate results.
The calculations attempt to translate data banks into a model that can then explain the events occurring inside of your equipment. Often times the computer processed model may develop imaginary information, thus leading to more questions than answers. With basic background and knowledge of variables that may affect your post processed data, your questions will start to be answered.
To introduce the initial creation of our mathematical model that is displayed upon our data collector or computer screen, (such as the time wave form or spectrum) we will explore commonly used hardware such as the transducer. In general the function of the transducer is convert one form of energy to another. A commonly used transducer for case mounted readings is an accelerometer. The accelerometer mimics mechanical vibrations to produce a usable signal. The usable signal is so small that typically an internal amplifier will be needed for your data collector to harness the information. This process is the initial creation of our mathematical model of data, which has been created from a response of a mechanical device (transducer) sitting upon a machine and is now being converted to a digital signal that has been amplified.
Now our signal must be stored for further analyzing. There are a number of vibration collector types and manufactures. The collector is very similar to a computer giving it the ability to quickly process the original signal into various mathematical models. One must take the time to do their research before purchasing a collector and the associated software. Many desired post processing and collection capabilities maybe limited such as sampling rates. With a good collector and setup your mathematical models will be accurate. The accuracy and consistency in your collections is key when managing your periodic collections.
With the basic knowledge of how your equipment generates your post processed model will make your time more efficient and your results accurate. The analyst will be able to identify data that is imaginary and pick out what is real. Take the time to understand your hardware and how your computer generates each model.
by Ana Maria Delgado, CRL
- Shaft speed of machine being analyzed
- Type of bearings involved (sleeve vs. rolling element)
- Rolling element bearing part number(s) and manufacturer(s)
- Internal configuration of equipment
- Machine History
- Proper data collection location
- Proper sensor to use for data collection
- Proper data collection setups to ensure correct data is collected
- Is the primary energy sub-synchronous, synchronous or non-synchronous?
- If the time waveform is collected in acceleration then what is the “g” level?
by Gary James CRL
Vibration analysis can detect the following bearing fault conditions:
- Defects on raceways
- Defects on rolling elements
- Defects in cage
- Looseness in housing
- Excessive clearances
- Bearing turning on the shaft
- Misaligned bearing
- Cocked bearing
- Lack of lubrication
by Trent Phillips
The Finger as a Sensor and Other Things That Are Of Utmost Importance!
Toyota did a study to find out why some equipment failed prematurely. They found that something like 80% of premature equipment failures could all be traced to three rather simple causes; causes that could have been prevented or remediated before they led to equipment breakdown. What were the three culprits?
b. Improper Lubrication
All three of these can be addressed by the vibration analyst during collection and analysis.
Looseness can be detected with a vibration analyzer. When you see looseness, use your finger as a sensor and run it around the interfaces of the bearing pedestals, housings, and foundations. It is surprising how sensitive one can be to the phase difference of shaking parts that have become loose. See that it is remedied before it causes catastrophic failure.
Inadequate lubrication can be detected by Shock Pulse. If you are taking high frequency acceleration readings it will cause a raised noise floor. This one is best avoided altogether by a well-planned and supported lubrication program. Often, by the time poor lubrication is detected, a considerable amount of damage has already been done. An electric motor’s winding insulation breakdown rate is doubled for every 18° F rise over 165° F. This is why motor cooling fins are actually for cooling and not for holding dust, grime, or whatever. Contamination is an important condition to monitor via a manual input point for each machine area. Add it to your route. Report equipment covered in whatever foreign matter your plant has lots of so it can be properly cleaned before damage is created.
Focusing attention on the three areas above will definitely create value for your company.
by Mike Fitch CRL
Most equipment failures are not age related. The equipment will provide some sign of impending failure if we have the right tools available to understand the change in condition.
A lot of facilities assign monitoring intervals based upon arbitrary schedules such as 30, 90, 180 or 365 days. Often this is due to a lack of understanding of how equipment fails, misunderstanding how conditional tasks such as vibration analysis work, available labor and lack of importance placed upon Condition Monitoring (CM) efforts. These arbitrary collection intervals can actually lead to failures that go undetected and a loss of value from the effort. The equipment will tell you how often monitoring must be completed. Not understanding this can lead to costly results!
How does your facility determine the correct monitoring intervals for CM efforts? Is it based upon man power, gut feel, P-F Interval or what someone told you to do?
by Trent Phillips
Combine vibration monitoring and ultrasound for more cost-effective predictive maintenance
The best overall machinery monitoring program is one that utilizes multiple, integrated monitoring technologies.
- The best overall machinery monitoring program is one that utilizes multiple, integrated monitoring technologies that are well-suited to detect expected failures modes.
- One goal of PdM is to determine how much time is left before a machine will fail, so plans can be made to minimize downtime and damage while still getting the most useful life from the machine.
- An application where ultrasound and vibration work well together is a mechanical inspection.
Reliability-centered maintenance programs are most effective and most profitable when a variety of appropriate technologies and tools are used to complement one another. Vibration analysis and ultrasound are as complementary as two sides of the same coin. Ultrasound is a useful monitoring tool, capable of detecting failing rolling element bearings and over- and under-lubrication conditions. The best overall machinery monitoring program is one that utilizes multiple, integrated monitoring technologies that are well-suited to detect expected failures modes. For low-risk machines, vibration analysis can be performed by a mechanic or operator using a vibration data collector or vibration meter. For machines of higher criticality, a certified vibration analyst should use advanced vibration data collection and analysis hardware and software.
Read my comments in this valuable PLANT SERVICES article.
by Trent Phillips
The Reliability Support Team at the Eastern Processing Facility located at Cape Canaveral Air Force Station, FL, won Uptime Magazine’s Best Design for Reliability Program award.
During the design phase of their program, the team was challenged with the implementation of Reliability-Centered Maintenance (RCM) principles and Precision and Predictive techniques from construction through commissioning. These have proven to be the most advantageous with regard to failure mode consequence reduction.
Congratulations to Frank Saukel, Garry Pell and their team for this prestigious award and a job well done!
1. Eastern Processing achieved Failure Mode Reduction with added redundancy.
2. They redesigned the facilities’ Reverse Osmosis Water System.
3. They performed Asset Prioritization based on safety, environmental, mission impact and probability of failure studies.
4. They trained technicians and engineers on RCM. In the words of Garry Pell: “Don’t expect to gain tribal knowledge if you don’t invite them into the Teepee. Get your people involved from engineering to safety, from shipping to operations.”
6. They developed all maintenance procedures based on RCM decisions.
7. They identified the Predictive Maintenance (PdM) technologies and tools they needed, met with different vendors at different IMC Conferences, then focused, implemented and trained on 1 or 2 maintenance and Condition Monitoring (CM) technologies annually, including:
• Lubrication analysis
• Vibration analysis
• Laser shaft alignment
• Infrared thermography
• Ultraviolet thermography
• Electric signature analysis
Many discrepancies were corrected using these PdM and CM technologies. According to Frank Saukel, “Every one of the PdM technologies have paid for themselves.” For instance, they identified misalignment and motor structure resonance conditions using their VIBXPERT vibration analyzer on several of their water pumps which had been aligned by a contractor.
Every pump was found to be bolt-bound and base-bound. They realigned all their pumps to excellent tolerance with their ROTALIGN ULTRA laser alignment tool.
They also found and corrected electrical deficiencies with ultraviolet thermography and detected sub-grade piping leaks with ultrasound. Their precision lubrication program included oil analysis, with a resulting reduction in the number of lubricants, minimization of cross contamination, and implementation of a color coded system for easy machine identification and the use of accessories to control moisture. Learn more…
by Ana Maria Delgado, CRL
Average – In vibration analysis, an average usually refers to the process whereby the vibration software will, after converting waveforms into spectrums via FFT, add the resultant spectrums together and then divide by the number of spectrums added together. The result is an “averaged spectrum”.
Band – A band is simply a range of frequencies e.g. A band from 0 Hz, to and including 5 Hz, is a band that is 5 Hz wide.
Band Pass Filter – A filter that blocks all data above and below its defined band.
Condition Monitoring – The use of specialized equipment to deduce the actual condition of equipment as pertains to its fitness for continued use. Condition monitoring is the foundation of Predictive Maintenance and the two terms are sometimes used interchangeably.
Cycles per minute (CPM) – In vibration analysis, cycles per minute refers to the number of vibratory cycles that occur in one minute of time. Cycles per minute is a quantity of frequency.
Cycles per second (CPS) – In vibration analysis, cycles per second refers to the number of vibratory cycles that occur in one second of time. Cycles per second is a quantity of frequency.
Enveloping – Enveloping, also known as envelope de-modulation, is a data processing technique whereby a spectrum is created from a demodulated or filtered waveform.
FFT – Fast Fourier Transform (FFT) is a mathematical process that transforms a waveform into the components of its frequency spectrum.
Fmax – Fmax stands for “maximum frequency”. It is the high frequency boundary for a set of data.
Fmin – Fmin stands for “minimum frequency”. It is the low frequency boundary for a set of data.
Frequency Markers – These are visible marks that can be overlaid on a spectrum at specific frequencies to help identify likely machinery problems.
Hertz (Hz) – The same as “cycles per second”.
High Pass Filter (HP) – This filter blocks all data below it and only allows the data that is higher to “pass” and be recorded. It determines the “low frequency cutoff” or Fmin.
LOR – LOR stands for “Lines of Resolution”. It is the number of digital bins of amplitude information a spectrum will be constructed from.
Low Pass Filter (LP) – This filter blocks all data above it and only allows the data that is lower to “pass” and be recorded. It determines the “high frequency cutoff” or Fmax.
Negative Averaging – A procedure whereby, having previously taken a reading, a second reading is taken and all data in the first reading that matches data in the second reading is subtracted.
% Overlap – % overlap is the amount several otherwise sequential waveforms, being sampled and averaged into a spectrum, will “overlap one upon the other” as they are being sampled.
Peak-to-Peak – The measure of vibration amplitude in a waveform, from the negative peak to the positive peak.
Unbalance – A measure that quantifies how much the rotor mass centerline is displaced from the centerline of rotation.
Waveform – In vibration analysis, a waveform is a display of vibratory energy over time.
by Trent Phillips
Vibration analysis is the best all-around technology for diagnosing and predicting problems in rotating machinery. Over the years I have seen time and time again where adopters of this technology have saved themselves and their companies countless man hours and thousands of dollars by getting to the root cause of a problem early on. By analyzing the data, they are able to schedule their valuable time on the right problem on the right machine long before the problem escalates into a major outage or emergency. But too many companies have not adopted vibration analysis. While it is true that one could spend many years learning the skills of the multiple levels of the vibration analysis disciplines, it is also true that even a basic understanding of the relationship of the time waveform and the spectrum can yield huge benefits and savings to a new user.
For example, the root cause of most roller bearing/seal failures is either shaft misalignment or rotor imbalance, which can take months to develop. It is also the most common problem analyzed within most facilities in the first two years of vibration analysis implementation. The good news is that misalignment and rotor imbalance are the easiest problems to diagnose by observing a high amplitude 1× running speed frequency in the spectrum. After that, a phase analysis with your analyzer can easily differentiate between misalignment or an imbalance problem, and quickly completed without shutting down the machine.
We all know that Rome wasn’t built in a day but we all must start somewhere and just a few days in an analysis class could yield major benefits to new companies.
Thanks to Jay Gensheimer with Solute LLC for this valuable post.
by Ana Maria Delgado, CRL
Setting the proper LOR is essential to be able to separate closely spaced defect frequencies. An example would be a pump with 5 vanes that could generate a “Vane Pass” frequency equal to the number of vanes, or 5 times rotational speed; if the impeller end of the pump had an SKF 7301BEP bearing, it could have an inner race defect frequency of 4.99 times running speed. This combination would require a relatively high resolution or LOR in order to have enough detail to separate the defect frequencies of each defect.
by Gary James CRL
Our training partners at Pioneer Engineering have created a few tips your organization can implement aimed at cutting costs without sacrificing quality and productivity.
Tip #1: Establish a Reliability Centered Maintenance Program
- A well established Reliability Centered Maintenance Program helps identify correct maintenance tasks to increase the reliability of the assets and cut costs by eliminating unnecessary PM tasks.
- Reliability Centered Maintenance Programs assist in clarifying maintenance responsibility and prevent costly unplanned downtime.
Tip #2: Perform a Criticality Assessment of all Assets
- Criticality Assessments will determine which components are critical to an operations efficiency and should receive the focus.
- Criticality Assessments quantify safety, environmental, operation, and repair cost consequences in the event of a functional failure.
- Perform Criticality Assessments on your spares inventory. Do you have the correct spares and quantity of spares in stock? Do you have unnecessary spares in stock that take up warehouse space and tie up capital that could be used elsewhere?
Tip #3: Avoid Costly Repairs by Analyzing Vibration Data on a Consistent Basis
- Consistent analysis allows the ability to monitor trends and detect problems before catastrophic failure occurs.
- Consistent analysis and trending allows flexibility in scheduling maintenance and reduced maintenance costs by preventing unscheduled downtime.
Tip #4: Avoid Fixing Repeat Offenders by Completion of Root Cause Failure Analysis
- Root Cause Failure Analysis will determine the underlying problem causing the failure to determine the best course of action
- Many failures are caused by operational issues instead of equipment or maintenance issues. A minor process adjustment may increase reliability and reduce costs.
Tip #5: Ask Questions
- Vibration analysis and other PdM technologies can help identify a potential issue but sometimes can be difficult to understand. Do not be afraid to seek expert guidance when potential issues are identified.
Need help improving and/or establishing a maintenance program in your company? Don’t hesitate to ask us how. We are here to help.
Thanks to the entire PIONEER ENGINEERING team for allowing us to share this article with you.
by Yolanda Lopez
Accumulation of dust and dirt on all rotor blades lead to a 1x vibration peak in the velocity spectrum. The sine waveform and phase analysis confirmed the results. A static unbalance was the reason for the increased vibration.
The balancing procedure was successfully performed on-site during the next shutdown phase of the plant. VIBXPERT II and OMNITREND software were used for the balancing runs. The static unbalance requires only a one-plane balancing procedure which was ideal for those fans. The accelerometers were attached to the non-drive end (NDE) bearing in horizontal direction. VIBXPERT offers a “second plane control feature” where the second accelerometer contorls any negative influence on the NDE bearing during trim runs. This ensures that the vibration on both bearing will be equally reduced and balanced. The target quality grade of 6.3 according DIN ISO 1940 was easily reached.
The plant went back online a few days later and the customer was extremely satisfied with the result of this service, who later stated:
“In the last 6 years, I have never seen those fans run so smooth.”
Special thanks to PRUEFTECHNIK Canada for sharing this successful story with us.
by Yolanda Lopez
Is your vibration analysis program or other Condition Monitoring technology simply predicting failures or also identifying the causes of the failures?
Vibration analysis is a very useful tool for identifying failure modes in equipment. Bearing failures, unbalance, misalignment, belt issues and many other problems can be easily identified with vibration analysis. However, the value of vibration analysis goes well beyond just simply identifying what equipment is about to fail. Stopping at this level will ensure that the same failure will most likely occur again in the future and identified again in the future by your vibration analysis program or other CM technology.
A good vibration analysis data collector and software will have tools to help you identify what is causing the bearings to fail, misalignment to occur, etc in your equipment. Use this additional functionality to identify the root causes of the equipment failures that your routine vibration analysis efforts uncover. This will allow you to eliminate the things that are causing the failures in your equipment. This means that your facility will replace less bearings, do less alignments, etc. on your equipment. This will save maintenance dollars and increase the overall reliability of your equipment.
by Trent Phillips
The vibration analyst is expected to use his or her tools to gather the right vibration data to determine the practical health of process equipment. To distill a systematic workflow of this task, it can more easily be understood in the terms of an “input – output” process. The inputs are data taken from the equipment, the output is actionable information which itself is a necessary input to an efficient maintenance process.
The inputs can be boiled down to 4 individual bits:
A. Frequency data
B. Amplitude data
C. Phase data
D. Other physical observation/information
These inputs are fed into a data analysis process which is expected to yield information dependable enough to help guide the actions of those caring for the equipment. Unfortunately, the old computer adage applies big time to the vibration analysis process: “garbage in, garbage out!”. If the input data (A,B,C and D referenced above) are not of good quality (garbage), then the analyst cannot output quality actionable information as input for the maintenance process within a facility. The results of the vibration program and analyst are called into question. Not only does the reputation of the entire vibration program suffer, but the facility will not benefit from the value that is offered by a vibration analysis program. It is the challenge of the vibration analyst to make sure that proper data is collected and correct analysis completed. This will allow for valuable information to be supplied to the maintenance process within a facility. Predictive technologies such as vibration analysis should be one of the core ingredients for the overall maintenance process (planning and scheduling, parts inventory, etc) at your facility. The only way to make this happen is to avoid the “garbage in, garbage out” effect and follow a “quality in, quality out” process with your data collection and analysis activities.
by Mike Fitch CRL
Fault frequencies are very important in vibration analysis, because they allow the analyst to correlate vibration data to specific components in the equipment that may be in some stage of failure (equipment faults). Fault frequencies change with any adjustment in the speed of the equipment being monitored. Most modern vibration data collectors and software will automatically re-calculate the displayed fault frequency information as the rotational speed of the equipment changes. Component information (bearing information, gear information, etc.) is required to calculate and display the fault frequencies of specific components in machinery.
It is important to create fault frequency setups at the beginning of a vibration analysis program. Not doing so will affect the overall success of the vibration analysis program.
by Ana Maria Delgado, CRL
Unbalance, misalignment, bearing failures, gear faults, motor electrical problems, etc. are typical faults experienced in all equipment. Identification and elimination of these faults and other issues are critical to maintaining the health of your plant equipment. Healthy equipment means lower maintenance cost, increased uptime, better product quality and a safer work environment for employees. This illustrated guide will help you determine the most common equipment problems using vibration analysis as a diagnosis tool.
Download your complimentary Machinery Fault Diagnosis Guide now!
by Ana Maria Delgado, CRL