AE is based on the detection and analysis of the high frequency component of sounds generated from the transient release of stored elastic energy from localised sources. These elastic wave frequencies are 25 kHz - 1 MHz of the system borne sound and are naturally generated by all machines and are above the hearing threshold. AE detects friction, impacts and metal removal which occur when machinery degrades. It is applied to virtually all rotating machinery, including slow-speed machinery, plain bearings and complex gearboxes. It is inherently immune to audible noise and low frequency vibrations.
Vibration in machines or structures can be detected and measured by using transducers to convert the vibration energy into an electronic signal. The signal is proportional to how fast it is moving (frequency) and how much it is moving (amplitude). The frequency says 'what is wrong' and the amplitude says 'how severe the problem is'.
Tribology and Wear Debris Analysis (Lubrication Management)
This method is used in systems employing petroleum-based or synthetic fluids such as lubricants or working media (hydraulic systems) and is based on analysing the wear debris entering the circulating fluid system to detect the onset of damage. The wear desbris is analysed by:
- Number of particles.
- Morphology and condition of particles.
- Particle sizing.
- Image analyser.
This method is based on:
- Heat flow – conductive, convective and radiative.
- The thermal behaviour of materials and the resulting 'thermal mass'.
- The resulting temperature changes from heat transfer which is measured.