What Is Vibration Analysis, and How Does It Work
Vibration is a very powerful tool for troubleshooting mechanical defects in machinery. It’s like getting an EKG for your heart; only sensors are used to pick up machinery vibration. Vibrations can reveal a lot about bearing defects, propeller problems, misalignment, and torsional problems. A vibration survey is a great way to get a good feeling for the condition of your machinery and have that confidence you’re not going to break down in the middle of an operation.
History of Vibration Analysis
Vibration analysis was very primitive in its nascent stages. Maintenance professionals started to see vibration become a problem when ships went from sail to steam. Steamships had reciprocating piston engines that were steam-driven, creating havoc. Ships were breaking in two. That’s when the invention of the propellor emerged, and for a while, propellers were used along with sails.
AME President Rich Merhige visited an engineering museum in Germany where ship models were on display. Different weights were placed on the vessels using springs to see how the ship responded to different vibrations. They used miniature seismographs with streaming paper. These are some of the earliest inventions of vibration analysis.
The Invention of the Microprocessor
The invention of the microprocessor enabled analysts to take massive quantities of data in a timewave format which could be converted to FFT, which was then used to convert into frequency. Analysts were able to observe plots of data and, through frequency analysis, were able to troubleshoot mechanical problems. Problems could be identified through pattern recognition and knowing the direction of where you’re taking the point. That’s where the experience of the analyst comes in. Certified analysts knows where to take the data, what frequency bands to look at, and have a general knowledge about which direction the vibration is, where the movement of the vibration is, and where things are oscillating. It helps them hone in on the root causes.
Combining the Microprocessor with Other Technology: Ultrasound
Then came Ultrasound. Analysts realized that combining microprocessors with other technologies, such as ultrasound for vibration detection, was a powerful way to pick up lower-frequency activity. This technology picks up air leaks, fluid leaks, and electrical issues. For example, if you have a very slow speed bearing, analysts can pick that up using Ultrasound. Also, if there’s a defect in that same bearing, analysts can hear it with ultrasound. The more different technologies combined, the higher the machine’s reliability level.
Combining the microprocessor with other technology: Infrared Thermography
Infrared picks up temperature differentials (emissivity) to where you can basically see the hot spots. If you have a misaligned machine, you can see the bearings overloading, and coupling overload. You can also pick up electrical defects, and hot spots. It really helps machinery operators visually see the defects. With composite structures, you can pick up if there’s water intrusion, delamination, etc.
Check back for part two, where we’ll take a deep dive into the latest vibration analysis technology.