What Is Vibration Analysis?

Vibration analysis is a popular machine condition monitoring technique that maintenance teams use to predict and prevent equipment failure. 

Vibration analysis is among the most popular types of non-destructive testing methods used in condition-based and predictive maintenance. The technique helps organizations in numerous industries diagnose, monitor, and prevent equipment failure for certain types of machines with rotating parts. 

What is vibration analysis? 

The vibration analysis process involves using specialized sensors to collect vibration signals and applying algorithms to recognize patterns, diagnose the sources of failures, and direct maintenance teams to take corrective action. 

Vibration and oscillation analysis tools and techniques are particularly useful for assessing any equipment or component that undergoes rotary motion. These include, but are not limited to: 

• Bearings, gears, shafts, and rotors: 
• Electric motors, turbines, fans, drive-trains, and gearboxes
• Pumps, piston engines, compressors, and other reciprocate machines

Vibration analysis in action

Here are just a few examples of how vibration analysis contributes to an effective predictive maintenance program in industrial settings. 

• Broken gears can cause trouble before you’ve had time to recognize an issue. With vibration analysis, your team can identify broken gear teeth earlier without disassembling any machinery. You’ll send out a work order before small issues have time to evolve into serious problems. 
• Bearing faults can cause excessive vibrations in machines with moving parts. Close monitoring can help you proactively recognize signs of bearing failures like overheating, corrosion, and misalignment to take corrective action.
• Corrosion inside oil pipelines is invisible to the naked eye, but close analysis of vibration patterns can uncover leak and fire risks. On a smaller scale, vibration data can draw attention to cavitation within individual pumps before it bubbles up into a costly breakdown. 

Vibration data has a range of additional applications. It plays an important role, for example, in measuring fluctuations in electromagnetic fields and assessing the structural integrity of bridges. 

Understanding vibrations in machinery 

All moving machinery vibrates while operational. Understanding these multi-dimensional waves and conducting effective vibration testing means grasping a few key concepts. Vibration-analyzing tools look at these factors and others to diagnose issues with machinery and offer clues about their severity. 

Amplitude

A wave’s amplitude is related to its magnitude. Often expressed with an RMS value, amplitude can be measured in a number of ways.

• Displacement: This refers to the distance between a wave’s resting position and its extreme positions on either side. You typically express it in terms of millimeters or micrometers.
• Velocity: This refers to the speed at which a component is vibrating. You can express velocity in terms of millimeters or micrometers per second. 
• Acceleration: This refers to the rate of change in a waveform’s velocity. Acceleration is at its highest a component’s movement reverses direction. You can express it in terms of millimeters or micrometers per second squared. 

Frequency

Typically expressed in terms of Hertz (Hz), frequency refers to the number of vibrations occurring over a particular period of time. 

Period

A vibration waveworm’s period is the inverse of its frequency. Period measures the time between two of the waveform’s troughs or crests.

Benefits of vibration analysis

As part of a comprehensive predictive maintenance program, effective machine vibration monitoring offers a number of benefits.  

• Drive down maintenance costs: Addressing failures proactively will help your organization avoid costly repairs and replacements. You’ll save money and support a healthier planet by reducing your energy consumption too. 
• Detect faults sooner rather than later: Sophisticated vibration analyzers can detect signs of trouble before they’ve grown severe enough that they’re audible to the human ear. With a more proactive approach, maintenance teams can preempt failures to minimize downtime.
• Improve maintenance planning and scheduling: More insights into the likelihood and severity of potential failures will help you optimize resource allocation to keep equipment reliability and technician utilization high while excess costs and unplanned downtime stay low.
• Keep your team safe: By helping predict breakdowns and draw attention to malfunctioning machinery, vibration analysis reduces the risk of accidents and potentially fatal injuries.  

Limitations and drawbacks of vibration analysis

This technique isn’t perfect, nor is it an ideal choice for every organization or every piece of equipment. 

• Effectively measuring and analyzing vibrations effectively requires special expertise and training.
• You cannot use vibration monitoring to detect fast-moving defects.
• Implementing vibration measurement sensors, vibration analyzers, and the necessary software requires an up-front investment.
• Vibration analysis does not always make it easy to localize faults within pieces of equipment and trace them to their root cause. 

Familiarizing yourself with the pros and cons of vibration analysis will help you easily determine when and how to employ the technique across your organization. 

Vibration analysis tools

To analyze vibrations as part of an asset management program, maintenance teams require specialized equipment.  

Vibration sensors

Different types of vibration sensors measure different types of vibration parameters. Examples include displacement sensors, velocity sensors, and accelerometers. In addition to the purchase price, the assets under your management, and your program’s overall goals, these factors may affect your choice of sensors:

• Vibration amplitude
• Sensitivity
• Bandwidth
• Noise
• Mounting options
• Sampling frequency

Portable vibration monitoring equipment

Sensors installed directly on equipment aren’t the only real-time data collectors available to you. You might also arm your technicians and operators with portable tools for condition monitoring. 

Vibration analysis software

Software helps put all that data to work. Supported by cutting-edge algorithms, vibration analytics tools use a number of techniques to detect anomalies, diagnose problems, and verify the health of components. 

4 steps for successful vibration analysis

A standardized, effective process for conducting vibration analysis is crucial for managing a condition-based maintenance program. Important steps for collecting, analyzing, and managing vibration data include:

1. Gathering data to establish a baseline
2. Measuring vibrations from your equipment
3. Analyzing and interpreting vibration data
4. Taking corrective measures to promote machine health

Step 1: Gather data to establish a baseline 

First, collect vibration data from the assets or systems you want to include in your condition-based maintenance program. If you’re introducing this program, you may opt for a pilot program with a single piece of equipment or a small number of assets. Make sure you’re installing the right types of sensors for the vibration frequency ranges and amplitude ranges you’ll be analyzing. Take note of your equipment’s typical operating conditions to ensure you understand what “normal” looks like and how different variables may affect performance. 

Step 2: Measure vibrations from your equipment

Next, you’ll leverage the appropriate sensors to measure relevant factors like vibration amplitude or velocity. 

Step 3: Analyze and interpret your vibration data

Then, your team of vibration analysts will leverage software solutions and advantaged algorithms to look at the data and begin matching anomalous frequencies to common types of failures. A deviation from the fundamental frequency, for example, could point to a misalignment, unbalance, or looseness. Your baseline assessments will come in handy here for comparing readings to established standards. 

Techniques for analyzing vibration data and conducting spectrum analysis include: 

• Time domain analysis: This technique involves assessing raw vibration sensor data over time to identify anomalies. Looking at the time waveform, it is possible to spot even minute deviations from the normal vibration levels.
• Frequency domain analysis: This technique leverages the Fast Fourier Transform (FFT), a mathematical frequency analysis operation which plots frequency against time. It presents analysts with a frequency spectrum that makes it easier to pinpoint specific types of faults.
• Envelope analysis: This technique, also referred to as demodulation, helps to detect bearing faults early. Analysts focus on the high-frequency vibrations created by damaged bearings. 
• Modal analysis: This technique is more advanced. It involves careful analysis of each machine’s natural frequencies to develop a more dynamic understanding of its performance.

Your team may identify fault frequencies like harmonics, which could point to gear-meshing concerns, or sidebands, which often indicate bearing faults. 

Step 4: Take corrective measures to promote machine health

Finally, establish thresholds that will trigger the appropriate corrective responses. You can use a combination of historical data, OEM recommendations, and industry standards to guide your initial planning and scheduling. Your go-to fixes will depend on the root causes of the problems you’ve identified and the tools at your disposal. 

Best practices for managing your condition-based monitoring program 

Your processes for vibration analysis and your maintenance strategy as a whole require strategic oversight to ensure your team consistently delivers on its goals. 

• Develop a routine: Analysis has to be done at regular intervals. Choose an appropriate interval to conduct vibration analysis. The interval chosen should reflect the machine characteristics and operating conditions. 
• Standardize the process: Standardizing the tools and techniques used to perform vibration analysis will help you guarantee consistent results and ensure your team is prepared to perform as efficiently as possible. 
• Keep detailed records: Your historical data is essential for learning from wins and losses and making the most strategic, cost effective asset management decisions possible. A good monitoring system should make it easy to save, access, and reference essential data. 
• Solicit feedback from your team: Nobody has more insights into the strengths and weaknesses of your maintenance strategies than the technicians and operators who put them in practice. They’ll provide real-world feedback to help you address bottlenecks, prioritize investments in both people and technology, and build a culture of continuous improvement.

Enhance your condition-based maintenance program with a CMMS

If you’re using vibration analysis as part of your maintenance program, you’re probably very familiar with the benefits of a Computerized Maintenance Management System (CMMS). In all likelihood, your team is already using one. 

There’s a big difference, however, between implementing a CMMS and implementing the right one for your organization. Only one CMMS or Asset Management platform earned a spot on G2’s Highest Satisfaction Products list: Limble. 

The right choice of CMMS platform can take even advanced maintenance programs to another level and help the function’s unsung heroes evolve into valued strategic allies. Download our CMMS Buyer’s Guide or schedule a demo with our team to learn more.