Direct-Reading (DR) Ferrography uses optical sensors to measure the density of particles collected and the ratio of large particles to small (fatigue-related catastrophic failure generally is characterized by generation of particles larger than 10-15 microns or um). The DR obtains two-(2) sets of readings: first for Direct Large (DL) >5um and the second for Direct Small (DS) ≤5um particles. The Wear Particle Concentration (WPC) is calculated by adding DL + DS = WPC divided by the volume of sample, establishing a machine wear trend baseline. Other helpful particle calculations include:
| 1. | Wear Particle Concetration | (WPC) | DL + DS = WPC |
| 2. | Percentage Large Particles | (PLP) |
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| 3. | Wear Severity Index | (WSI) | (DL + DS) (DL - DS) = WSI |
Analytical Ferrography employs both quantitative and qualitative parameters including optical microscopy and photo microscopy techniques for the evaluation of equipment particles. This evaluation involves discriminating the particles by Size, Shape, Composition & Concentration. The test provides in-depth analysis of particle makeup (e.g., steel, copper, bronze, aluminum or corrosive) and relating these various particle types to four-(4) known wear contacts (e.g., rolling, sliding, spinning or impaction contact).
