The Value of Continuous Vibration Measurements

August 5, 2014

Advanced vibration analyzers like the VibXpert have powerful analytical features that often go underutilized. One such feature is the ability to acquire continuous (live) vibration measurements. This can be utilized to check for measurement signal stability and quality. However, it can also be used for additional analytical troubleshooting as well. Continuous (live) vibration data can be used to determine if electrical energy (faults, etc.) is present in electrical motors. Set your vibration analyzer to continuous monitoring. Identify and watch the peaks in question. Turn the motor off while watching the peak(s) in the measured data. Peak(s) that disappear immediately when motor power is turned off are related to electrical energy. Remaining vibration data is associated with rotating components within the equipment.

Continuous data collection can be activated in the VibXpert analyzer by selecting the Multi-Mode icon and then the Data Collection icon that will be used. Press the Menu key, select the display setup option and toggle continuous measurement to “Yes” (it is set to “No” by default). Alternatively, you can activate the live mode by keeping the “Enter” key pressed when the measurement starts. The actual data collection begins when you release the “Enter” key.

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Determining Proper Equipment Data Collection Intervals

July 31, 2014

Guest post by Brad Loucks, Mechanical Engineer at Pioneer Engineering

In a condition monitoring vibration program, determining the appropriate intervals of data collection is just as important as the data that is being analyzed. Properly scheduled data collection intervals of equipment provides data analyst with a better picture of how equipment is performing over a period of time. Having a history of data is important for in an effective condition monitoring vibration program and this is done by establishing correct data collection intervals.

Data collection intervals should be established and executed with purpose, not done randomly. To establish intervals, it is important to know and understand how equipment works. Determining the appropriate time interval between collections is done by identifying how often the equipment runs, how fast it runs, and the application. The calculations are based on the estimated life cycle of the bearings but also the estimated amount of time it takes to go from a defect to complete failure.

Collection intervals should be a routine function. Many times data collection falls behind because the collection person is too busy to collect the data. One of the most common issues that I have come across is that plants will begin to collect data and then the person collecting the data gets pulled to do other work and the data collection gets missed and becomes more random. This is a slippery slope in that it almost always leads to the data no longer being collected. Then when an emergency comes up such as a bad sounding machine, the analysis has not been collecting a history on the equipment but they have also been out of the analysis for so long that they have a difficult time remembering how to analyze. The history and interval is just as important for a proper analysis as it helps to give the analyst a more accurate analysis by allowing them to see the progression timeline.

Bearings often do not fail in a predictable time span. If this were the case, vibration analysis could be overlooked and time-based maintenance could be used. A bearing can go from a known defect to catastrophic failure over the course of a few years or it can happen within minutes. The collection intervals are calculated so that not only can data be collected and the severe defects be identified, but also to identify when a defect has formed and allow for a history to be built in order to watch the progression of the defect. This can aid in determining whether immediate action should be taken or if the defect is at an early enough stage where proper planning and measures can be taken to avoid an immediate shut down and loss of production.

If the equipment is deemed valuable enough or if unplanned downtime is just out of the question, then calculated collection intervals are a necessity of a proper condition monitoring vibration program. Through proper maintenance, a condition monitoring vibration program can save a plant both time and money in reducing or eliminating unplanned downtime, as well as significantly reduce the possibility of injury or death of plant staff due to catastrophic equipment failure.

Download our Calculations of Bearing Defect Frequencies

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Your equipment is what it eats!

July 29, 2014

Engineering advancements have resulted in many different types and grades of lubricants being available for equipment maintenance. Unfortunately, the risk of improper selection and mixing of lubricants has increased as well. Mixing different types of lubricants (grease and oil, etc.) within a machine is one of the most common equipment reliability problems. Doing so can result in unanticipated chemical reactions and equipment failures.

Proper labeling is a method to help ensure that the correct type of grease or lubricant is being injected into your equipment. Color coded labels with proper lubricant identification markings should be placed on the Zerk fitting or near any lubrication entry point on a machine. Grease guns and lubricant containers should have the same color identification and markings as well. This simple process can assist in eliminating lubricant contamination and thereby prevent one of the most common reliability problems today.

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How your Equipment Generates a Mathematical Model

July 24, 2014

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.

 

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Do you have duplicate data in your OMNITREND software database?

July 22, 2014

Have you ever collected data and uploaded the data back into OMNITREND only to realize that you have duplicate data in your database? As a technician, you are pressed for time and your boss needs that report like yesterday. Every so often, when uploading the data you can get distracted by other people or from trying to juggle too many things at once, and you inadvertently upload the data twice.

You can delete the duplicated data without having to delete each one-by-one! Here’s how:
• Click Tools
• Select Report
• Select OMNITREND Web
• Click OK
• Click Database
• Select Database Utilities
• Select Data cleanup
• Once the data cleanup is complete click Close
• In OMNITREND click Database
• Select Database Utilities
• Select Compact & Repair

Once the Compact & Repair process is complete you can go into Machinery Manager, drill down into you database, select the task and then click the Edit Meas. Data tab on the right hand side of the screen, and you will notice the duplicate data has been deleted.

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Reliability Improvement – The Next Step after Condition Monitoring

July 17, 2014

Guest post by Mitch Stansloski, P.E., PhD., Founder and President of Pioneer Engineering

I find that in today’s economy, many of our clients have added, or are attempting to implement, an effective condition based maintenance program. These clients understand the value of this type of program over and above the traditional time-based maintenance strategies. However, it is important to note that if a program stops at this step, it is unlikely that there will be significant improvement in overall reliability or a large reduction in maintenance costs.

This may sound a bit shocking, but based on my 26 years of maintenance and reliability experience, it is absolutely true. Think about it this way: Using condition monitoring to find defects early will not reduce the number of malfunctions that would have occurred if the technology had not been applied. It will give the user time to prepare for the repair, which will save some unplanned downtime, and it will likely reduce the severity of the failure resulting in less repair cost as well. However, decreasing unplanned downtime doesn’t improve reliability, it only improves availability, which is not as valuable. In addition, the costs savings that result from a more minor repair will be offset by the costs of implementing the technology (e.g. instrumentation, software, computers, maintenance fees, etc.) and the manpower to operate it.

In order to improve reliability, the program needs to add steps which focus on reliability improvement. Rather than stopping at diagnosing and replacing a defective bearing for instance, the user needs to identify a root cause for the premature failure. Then the user needs to change how the asset is managed in order to prevent recurrence. If these steps aren’t completed, the replacement part will likely see the same shortened life. Changes to asset management could include revisions to:

  • Installation and setup procedures
  • Maintenance procedures
  • Operating procedures
  • Purchasing specifications
  • Spare parts requirements

Taking these next steps can move a “parts swapping program” facilitated by high tech condition monitoring into a true reliability improvement program.

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