This blog post continues an 8-part series on vibration analysis written by Dr. Sara McCaslin & Nolan Crowley, Business Development Manager at HECO.
Dr. Sara McCaslin: Sara has a Ph.D. in mechanical engineering from the University of Texas at Arlington. Sara has also taught materials science, manufacturing, and mechanical system design at the University of Texas at Tyler.
Nolan Crowley: Nolan has BS from Miami University along with extensive field experience with powertrains, electric motors, & vibration issues since 2007.
- Week 1: Vibration Analysis Training: Who’s Doing Your Analysis?
- Week 2: Vibration Analysis Equipment: Sensors and Hardware
- Week 3: Balancing Rotating Equipment: Static vs Dynamic
- Week 4: The Importance of Route-Based Data Acquisition
- Week 5: The Basics of Modal Analysis for Electric Motors and Powertrains
- Week 6: How to Setup Remote Monitoring Vibration Monitoring
- Week 7: The Place of Motion Amplification in Modern Vibration Analysis
- Week 8: Bidding/Specifying Your Vibration Analysis Program
Subscribe to HECO's blog, Here You Go to learn from this valuable 8-part series on vibration analysis.
Machines don’t just suddenly fail -- they do give warning signs. And route-based data acquisition is an effective way to recognize those warning signs and prevent many different types of failure.
There have been countless facilities that have found route-based data acquisition to be a serious game-changer for the reliability and life of their rotating equipment. A good example is California’s Orange County Sanitation Department. After implementing route-based vibration analysis best practices as part of PdM, maintenance and repair costs were reduced and the resulting ROI was 7.3:1 -- but what makes it so effective?
What is Route-Based Data Acquisition?
Route-based data acquisition refers to the process of regularly collecting data about your equipment by following a specific route through your facility. Basically, a technician follows a pre-planned route that takes them to equipment. At each piece of equipment on the route, performance data (usually vibration data) is gathered and then analyzed.
The Purpose of a Vibration Route
On a vibration route, data related to vibration is collected on a regular basis from the machines included in the route. The vibration data gathered provides a wealth of information about how the condition of the equipment has changed since its last check, including factors such as bearing wear, bolts that have come loose, or the development of an eccentric air gap between the rotor and stator.
Note that the first few times the route is followed, baseline vibration data is acquired. This provides an idea of what normal operation for a particular machine looks like. After that, comparisons can be made between new data and baseline data to reveal changes in operation and performance.
After a route is complete, the data is analyzed and a report is prepared. The vibration analysis report contains recommendations concerning the need for maintenance or repair as well as a discussion of potential failure modes and changes with reference to baseline.
Data Collected from a Vibration Route
Data collected from a vibration route are primarily related to time waveform measurements and frequency spectrum data. Most vibration analysis equipment can automatically transform the time waveform into frequency spectrum (frequency domain) data via a mathematical operation known as a Fast Fourier Transform, or FFT. Then a certified vibration analyst can study this data for each machine to identify patterns and other signs of potential problems.
What Route-Based Rotor Vibration Analysis Reveals
So what kind of issues can be detected through a vibration? In the hands of a qualified analyst route-based rotor vibration data reveals things such as ...
- Mechanical looseness (e.g., loose bolts, broken welds)
- Bearing defects
- Eccentric air gaps between the rotor and stator
- Resonance conditions
- Bent shafts
- Belt problems
- Faults in gear drives
Analysis does get complicated when there are multiple fault conditions at work (e.g., worn out bearing and a misalignment) but a skilled analyst can decipher the individual signs of potential failure.
What Equipment Should be Included in a Vibration Route
To get the most out of route-based data acquisition, careful consideration needs to be given to what to include on the route.
Here’s a great rule of thumb to help you start the process of choosing rotating machinery to include: if your facility comes to a grinding halt when it fails, then include it on the route. This allows your route to focus on the most important equipment in your facility: the equipment whose downtime has a domino-like effect on everything else. It’s also wise to consider hard-to-replace equipment, equipment that poses safety risks if it fails, and equipment that is costly to repair or replace.
However, if a machine is difficult (or dangerous) to access or operates under varying speeds or loads, it’s usually best to not have it on your route. In these situations accelerometers can be hard wired in or cables can be extended to keep the analyst safe and away from rotating equipment.
How Often Should a Route be Tested?
Vibration routes are usually performed monthly, bimonthly, or quarterly. The more often a piece of equipment is tested, the more costly the vibration route will be. To achieve a good balance between route costs and benefits, some people categorize assets based on their criticality. High criticality equipment is tested monthly while medium criticality equipment is tested quarterly.
Also, keep in mind that how often equipment is tested isn’t set in stone. For example, equipment that is proving to be extremely healthy might be moved from monthly to quarterly testing. On the other hand, machines with repeated fault conditions may need to be monitored more often.
Benefits of a Route-Based Vibration Testing
When included as part of a PdM (Predictive Maintenance) plan for your rotating equipment, vibration analysis can identify, predict, and prevent several different types of failures in your rotating machinery. This can lead to significantly reduced downtime as problems are detected before they become time-consuming failures. It’s faster to repair a worn bearing before it starts to cause damage and other complications. In addition, repair costs also go down because issues can be addressed while still in the beginning stages.
You also have far more control over when maintenance and repairs take place, allowing you to schedule them when they’ll have the least impact on your facility. Maintenance costs can also go down when it is performed as needed, rather than when something fails or according to a schedule that doesn’t take your equipment’s needs into account.
The same vibration analysis data can also be leveraged to help you make informed decisions about your equipment, such as when equipment needs to be repaired, rebuilt, or replaced. And you will likely find the useful life and value of your equipment enhanced.
The use of route-based data acquisition for vibration analysis is highly recommended for increasing the reliability of your equipment as well as other benefits just discussed.
At HECO, we provide vibration analysis, including vibration routes, as part of our PdM services. We can help you identify the best equipment to include on your route, decide how often the route should be followed, assist you in carrying out the route, and provide you with certified vibration analysts who can decipher even the most complex confluence of failure modes. Contact us today!