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Wear Particle Atlas CD-ROM Features Index

Part 4, Integration of Ferrogram and Filtergram Methods
Wear Particle Atlas CD-ROM

The Integration of Ferrogram and Filtergram Methods feature is one off our main features of the Wear Particle Atlas. The ferrogram method is excellent in identifying the materials and the size and shape of solid particles, but is deficient in collecting nonferrous particles. The filtergram method collects all solid particles larger than the pore size of filter paper, but is restricted in identifying materials of solid particles. The Wear Particle Atlas CD-ROM exclusively combines the two types of analysis. It takes advantage of the best features of both the ferrogram and filtergram methods thus compensating for their respective limitations to maximize the strengths of microscopic wear particle analysis.

Figure (a) below shows an easy identifiable, nonferrous (lead/tin alloy) wear particle image on a ferrogram. Their non magnetic deposition pattern makes the discrimination of the lead/tin particles from the ferrous particles easy. These nonferrous particles are difficult to identify on the filtergram. In this case, the color and brightness of both ferrous and lead/tin alloy particles are very similar, see figure (b), due to lack of the deposition features in orientation and locations as on a ferrogram, figure (a).

(a) Lead/tin particle on ferrogram

(b) Lead/tin particle on filtergram

The filtergram method is, however, able to collect nonferrous metal particles with high efficiency. This capability contributes to its high reliability to detect the condition of nonferrous components. Figure (c) shows the massive rubbing copper wear particles on a filtergram from a worm gearbox, revealing a high wear rate of the copper worm gear. But the ferrogram, made of same volume of sample, shows a very low copper particle concentration, as shown in figure (d). It is estimated that the collecting efficiency of the ferrogram method for small copper particles is likely to be less than 10% in this case.

(c) Copper particles on filtergram

(d) Copper particles on ferrogram

Thank you for visiting the "Integration of Ferrogram and Filtergram Methods" feature of the Wear Particle Atlas CD-ROM. Additional features can be reviewed by returning to the Wear Particle Atlas CD-ROM Features Index.