Vibration analysis is the process of measuring and analyzing your assets’ vibration patterns. It’s one of the most effective ways to keep your equipment up and running for longer while lowering your overall maintenance spend.
Changes in vibration patterns can indicate that an asset is unbalanced, misaligned, or has a bearing fault. Modern vibration sensors are sensitive enough to pick up on subtle changes in vibrations so that technicians can spot problems early and repair them before they cause breakdowns.
We’ll take a dive into how vibration analysis works and we’ll get into some of the most common approaches.
What is Vibration?
Vibration is the back-and-forth motion, or oscillation, of an object around its equilibrium position. A guitar string vibrates when you pluck it; an engine also vibrates when it’s running.
It’s normal for motor-driven assets to vibrate during operation – to an extent. However, excessive vibration can indicate a problem brewing within your equipment. Bent shafts, misaligned parts, and unbalanced assets can all cause abnormal vibrations. Reliability engineers diagnose these issues by analyzing vibration patterns.
What are the Characteristics of Vibration?
Vibration has three important characteristics:
- Amplitude
- Frequency
- Direction
Each characteristic provides important information about asset health.
Amplitude (also called displacement) refers to the magnitude of vibration. The greater the amplitude, the larger the oscillations are. On a waveform, the amplitude is typically measured peak-to-peak.
Amplitude is a good way to measure severity; higher amplitude can indicate a more severe issue.
Frequency refers to the number of cycles that a vibrating object completes per second. Frequency is measured in hertz.
Direction refers to the movement of the vibrating object. Direction may be axial or radial, for example.
How is Vibration Measured?
Vibration analysts typically use handheld vibration analyzers and wireless vibration sensors together with condition monitoring software to measure vibration levels and frequencies. The most advanced vibration analysis programs also use artificial intelligence.
The most common type of accelerometer is the piezoelectric sensor, which converts physical vibrations into electrical signals. Those signals are recorded as vibration data. Software then organizes and analyzes the data, either as a waveform or a Fast Fourier Transform, or FFT.
Depending on the plant, technicians may want to install wireless vibration sensors which measure vibration data in real-time. Some operations prefer to do route-based vibration measurement using a handheld vibration analyzer, like the VibXpert II from Pruftechnik.
After collecting vibration data, the next step is analysis.
How Does Vibration Analysis Work?
Vibration analysis takes vibration data and makes sense of it so that maintenance teams can take action and make any necessary repairs. There are a few different ways to analyze vibration data: spectrum analysis and waveform analysis.
What is Spectrum Vibration Analysis?
Spectrum analysis takes vibration data and “decomposes” it, letting technicians study each component separately. Instead of looking at the overall vibration levels, spectrum analysis presents vibration signals in the frequency domain.
Spectrum analysis is a great way to pinpoint the location of a machine fault. Machine components vibrate at different frequencies when they are breaking down. Bearings, for example, tend to vibrate at higher frequencies when they are faulty.
Modal analysis uses software to create a visual display of an asset’s frequency responses. Some teams use animations to create a visual map of all the different vibration modes.
What is Waveform Vibration Analysis?
Waveform analysis displays vibration signals in the time domain. A simple sine wave, for example, maps vibration levels over time. This is a great way to get an overall picture of vibration events and to spot any alarming anomalies.
Waveform analysis can tell you how severe vibrations are. It can also pinpoint exactly when the most extreme vibration is happening. The “peaks” of a waveform point to shock events. Studying a waveform can tell you at what point in the operating cycle these shock events are taking place.
Technicians also look at RMS (Root Mean Square) to determine the intensity of vibrations. RMS measures the overall energy caused by your asset’s vibrations. It’s a useful metric for gauging the severity of the problem.
Machine Vibration Analysis Methods
Vibration analysis is one of the most effective techniques for spotting defects in rotating machinery. Done right, vibration analysis can help teams identify machine faults early so that maintenance crews can make repairs right away.
For a long time now, plants have been using vibration analysis as part of a preventive maintenance strategy. Today, more and more operations are using vibration analysis as a key part of a predictive maintenance and condition monitoring approach.
What Can Vibration Analysis Discover?
Vibration analysis is like an early-warning system for your plant. Today’s vibration sensors are finely-tuned; they pick up on the tiny changes in vibration that point to a machine defect.
The four most common machine faults in rotating machinery are
- Imbalance
- Misalignment
- Bearing faults
- Looseness
Left unchecked, these problems can develop into major headaches, causing shutdowns or drops in productivity. That’s where vibration analysis comes in.
Vibration analysis identifies the first signs of imbalance, misalignment, bearing faults, or looseness. This means that maintenance crews can schedule repairs when it’s convenient. It also means that the issues don’t balloon out of control.
Vibration Analysis Examples
Just about any operation can benefit from vibration analysis. Automotive, manufacturing, and oil and gas all make use of vibration analysis to keep their operations up and running.
What is Vibration Analysis in Maintenance?
Maintenance teams use vibration analysis to identify early signs of imbalance, looseness, bearing faults, or misalignment.
Most operations today are operating on a tight production schedule, with no margin for downtime or drops in production. The typical plant also has far more critical assets than in the past. At the same time, most teams are facing labor shortages.
All of this means that it’s more important than ever to keep assets running smoothly. Vibration analysis helps teams stay on top of new and developing machine faults. It’s also a good way to build some margin into your maintenance schedule, by identifying faults early enough to address them whenever is most convenient.
Often, maintenance technicians will collect data during their routes using handheld vibration analyzers. Then, those vibration measurements will be analyzed by in-house reliability engineers or external condition monitoring services, like those offered by Fluke Reliability.
Common Examples of Vibration Analysis
Every rotating asset has a standard vibration “signature.” When that signature changes, it’s a sign that something is wrong.
Motor-driven assets like pumps and air compressors are great candidates for vibration analysis. Putting a vibration sensor on your pumps and compressors will help you catch early signs of trouble so that you can nip it in the bud.
Vibration Analysis Tools
Vibration analysis tools are sensitive enough to catch subtle signs of trouble. Most of them are intuitive to use, even for people who don’t have a technical background.
What is a Vibration Sensor?
Sensors measure and record vibration acceleration, velocity, and frequency. Your technicians can install vibration sensors on almost any asset or component you want to monitor.
Wireless sensors can collect vibration data continuously and transmit it in real-time, so that you’ll never miss a thing. You can also program most sensors to alert you when vibration levels cross a certain threshold.
What is a Vibration Analyzer?
Vibration analyzers are typically compound instruments: they’re part sensor, part computer. Vibration analyzers are fitted with piezoelectric accelerometers to measure vibration levels. They also analyze that data and display it. Some vibration analyzers can diagnose machine faults and guide users through repairs.
What is Vibration Monitoring?
Vibration monitoring uses sensors and data analytics to keep constant tabs on your most critical assets. Most plants don’t have the staff to monitor all of their equipment manually. Using a network of vibration sensors and analyzers ensures that you’ll stay on top of problems and make the most out of your limited resources.
Condition Monitoring Vibration Analysis
Condition monitoring tracks the overall health of your equipment using sensors and data analytics. Its goal is to catch new machine faults while they’re still small and manageable. Done right, condition monitoring can alert you to signs of an issue weeks, or even months, before they turn into a problem.
Vibration analysis is a key part of any condition monitoring strategy. By identifying tiny changes in vibration levels, vibration analysis helps teams stay ahead of problems.
Condition monitoring depends on sensors, software, and IIoT tools to capture and analyze data. Most teams will need some training to implement a condition monitoring program, but the tools are still intuitive to use.
It’s a solid approach for expertise-constrained teams, or for plants operating on a lean budget. And of course, it’s a great way for anyone to see more results in terms of uptime and greater reliability.