Ultrasonic inspection and monitoring of bearings is by far the most reliable method for
detecting incipient bearing failure and conditions such as lack of lubrication. The
ultrasonic warning appears prior to a rise in temperature or an increase in low frequency
vibration levels. Ultrasonic inspection of bearings is useful in recognizing:
a. The beginning of fatigue failure.

b. Brinelling of bearing surfaces.

c. Flooding of or lack of lubricant.

In ball bearings, as the metal in the raceway, roller or ball elements begins to fatigue, a
subtle deformation begins to occur. This deforming of the metal will produce irregular
surfaces, which will cause an increase in the emission of ultrasonic sound waves.
A change in amplitude from the original reading is an indication of incipient bearing
failure. When a reading exceeds a baseline reading by 8 dB with no substantial change in
the sound quality, it can indicate lack of lubricant. If the reading exceeds a baseline by
12 dB, it can be assumed that the bearing has entered the beginning of the failure mode.

ULTRASOUND ADVANTAGES
The advantages of ultrasound condition monitoring are many.
• Users can hear in real-time the sounds of operating equipment
• Ultrasound is a localized signal, which helps operators identify a sound source
• Ultrasound provides early warning indications of failure conditions
• Heterodyned sound samples can be recorded and analyzed on a PC
• Sound samples can be both heard in real time when analyzed on a PC
• Sound samples can be viewed on Vibration Analyzers, providing high resolution
• Ultrasound will detect lack of lubrication & prevent over lubrication
• Ultrasound instruments are extremely effective for Condition-Based Lubrication
programs
• Ultrasound is very effective for monitoring slow speed bearings
• Ultrasound is very effective for monitoring bearings of all speeds
• Software provides important data for, trend reports, alarm grouping and analysis
• Ultrasound can trend cavitation problems
• Ultrasound detects faulty gear teeth
• Ultrasound instruments can be used in noisy environments
• Ultrasound instruments support other technologies