Part 4, Integration of Ferrogramand Filtergram Methods

Wear Particle Atlas CD-ROM

The Integration of Ferrogram and Filtergram Methods feature is one offour main features of the Wear Particle Atlas. The ferrogram methodis excellent in identifying the materials and the size and shape of solidparticles, but is deficient in collecting nonferrous particles. The filtergrammethod collects all solid particles larger than the pore size of filterpaper, but is restricted in identifying materials of solid particles. TheWear Particle Atlas CD-ROM exclusively combines the two types of analysis.It takes advantage of the best features of both the ferrogram and filtergrammethods thus compensating for their respective limitations to maximize thestrengths 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 patternmakes the discrimination of the lead/tin particles from the ferrous particleseasy. These nonferrous particles are difficult to identify on the filtergram.In this case, the color and brightness of both ferrous and Lead/Tin alloyparticles are very similar, see figure (b), due to lack of the depositionfeatures in orientation and locations as on a ferrogram, figure (a).

The filtergram method is, however, able to collect nonferrous metal particleswith high efficiency. This capability contributes to its high reliabilityto detect the condition of nonferrous components. Figure (c) shows the massiverubbing copper wear particles on a filtergram from a worm gearbox, revealinga high wear rate of the copper worm gear. But the ferrogram, made of samevolume of sample, shows a very low copper particle concentration, as shownin figure (d). It is estimated that the collecting efficiency of the ferrogrammethod for small copper particles is likely to be less than 10% in thiscase.

Thank you for visiting the "Integration of Ferrogram and FiltergramMethods" feature of the Wear Particle Atlas CD-ROM. Additional featurescan be reviewed by returning to the Wear ParticleAtlas CD-ROM Fetures Index.

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