Companies are constantly progressing on their maintenance journeys. A trend of shifting from preventative maintenance to predictive maintenance has occurred for many large organizations. Predictive maintenance, like equipment vibration analysis, can help find problems before they become major issues and cause equipment outages. In this article we guide you through how this form of predictive maintenance works.
How Equipment Vibration Analysis Works
Simply put, when a piece of equipment is in operation, it osculates (or rotates) around a reference point. The number of times it completes this cycle within one second, is its frequency. You measure the frequency of a piece of equipment in hertz (Hz).
When this rotation becomes imbalanced, vibration increases. This increased vibration causes machinery conditions to degrade over time and can lead to break downs.
According to TWI Global, vibration analysis is “A process that monitors the levels and patterns of vibration signals within a component, machinery or structure. This is done to detect abnormal vibration events and to evaluate the overall condition of the test object.”
Our technicians use vibration analysis tools to collect this data and upload the information into a software for interpretation. We can then compare the frequency of your equipment to the accepted industrial standards the manufacturer’s specify.
How To Measure Vibrations
Vibration can be measured by using sensors. The type of sensor used determines what is measured. For instance, some sensors measure vibrations and displacement, while others measure velocity and acceleration. Some common sensors include piezoelectric (PZT) sensors, laser doppler vibrometer, proximity probes, accelerometers and microelectromechanical sensors (MEMS).
These sensors can be attached to all sorts of equipment to gauge performance. Some common equipment includes:
- Piston Engines
- Reciprocating Compressors
What’s Important When Collecting Data?
When using sensors it is important to get measurements from the horizontal, vertical and axial axes on both ends of the equipment. This will give you a full-spectrum vibration signature and a complete picture of your equipment. It may also help you catch issues that you can’t spot on any one axis.
What Does Vibration Analysis Software Tell Us?
To the trained eye, the vibration data can reveal when the equipment is starting to fail. It can indicate broken welds or bolts, failing bearings, rotor imbalance, cavitation in pumps and misaligned shafts. It can also indicate resonance; the phenomenon in which a separate vibrating force is causing the examined piece of equipment to fail.
One way to visualize vibrations is through operating deflection shapes (ODS) simulators. These 3D simulations exaggerate vibrations found in machinery allowing you to visualize the forces.
Early problem detection has become more important as operating speed ranges have increased to between 0 – 3600 rpm for a lot of rotating equipment. By tracking these rotation frequencies we can find imbalances in rotating parts, mechanical looseness, fluid-induced instabilities, gear faults and other mechanical failures.
When faults occur, it can be hard to understand the reading. Faults will generally differentiate themselves by:
“Synchronicity to machine running speed, the frequency range at which the peaks occur in the spectra, which peaks are present and which are not, etc.” – credit to Jacob Bolhuis
With proper training you can use these peaks, frequency and running speeds to identify the issue at hand quickly.
How Vibration Analysis Can Be Used
Single use vibration studies can be effective, and they do help prevent failures ahead of time. However, it’s best practice to make vibration analysis a routine maintenance.
This way, we can establish a baseline for all pieces of equipment and then monitor their change overtime. Each piece of equipment may receive a monthly or quarterly report that includes the following details:
- Equipment Name
- Date of Vibration Analysis
- Chart of Vibration Analysis
- Description of Analysis
- Fault Detected (if present)
- Recommended Action
- Completed Actions
- Historical Trend of Vibration Analysis to depict how Completed Actions have impacted the piece of equipment.
Equipment Vibration Analysis Report (Case Study)
The analysis report pictured below was taken at a food processing plant. Spectrum data was collected at a location opposite the drive end motor bearing.
The plant in question would lose $168 per minute of downtime. This allowed us to make the recommendation from the findings below to replace motor bearings immediately. This helped the plant avoid what would have caused an extended period of downtime and a lot of money!
Note: Motor Current Signature Analysis (MCSA) is another way to analyze equipment. Using sensors, motor current readings are recorded and analyzed in the frequency domain.
Scheduling Equipment Vibration Analysis
We can perform a one-time callout analysis or periodic contract monitoring. By acquiring a baseline of vibration, your equipment can be compared against itself in the future. This allows us to troubleshoot recurring problems with root-cause analysis and discover issues before they become larger problems.
Vibration Analysis Draw Backs
While the upside to vibration analysis is high, it is important to consider drawbacks before you decide to use this tool.
One drawback is that vibration analysis requires an initial setup and monitoring to create a baseline for the equipment in most cases. A second is that you need to ensure you have a properly trained technician perform the testing. If not, data can be collected improperly and results can be misconstrued. Finally, failing bearings are hard to recognize by some systems. This is because pressure and speed have increased on many systems.
While these drawbacks should be considered before making the choice to use equipment vibration analysis, the upsides can be tremendous. The larger the facility or plant, the larger the benefit is, especially when downtime costs are high.
Our Reliability Department
Our Reliability Services department uses the latest technology to detect problems before they occur, preventing downtime and lost revenue. We help you save money by maximizing up-time, efficiency, reliability, and equipment life. Our customer-focused and consultative approach means we bring quantifiable results that focus on your unique facility. We provide:
- Vibration Analysis
- Infrared Thermography
- Ultrasonic Leak Detection
- Fluid Analysis
- Laser Shaft Alignments
- Wear Particle Analysis And Ferrography
- Dynamic Fan Balancing