Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/258778
32 January - February 2014 | www.machinerylubrication.com samples in parts per million (ppm) as reported by the third-party laboratory. It should be noted that no particles larger than 3 to 4 microns would be detected in these results due to the limita- tions of ICP. Based on the table, the majority of the components in each of the three samples were salts and minerals such as calcium, phosphorus and sodium. There was a significant portion of zinc or molybdenum and boron, which could be coming from additives, coatings and possibly some bearing wear. All three samples also showed some iron and copper, which would suggest motor wear. However, metals like aluminum, tin, nickel and chromium were all but absent. The key difference with SEM/EDX data is that you not only get the individual particle size and shape but also the actual particle chemistry for each particle detected. The particle chemistries can then be classified into various "rule classes," which are established based on various metal chemistries. Tables 4 and 5 present the SEM/EDX results of each of the particle counts for all three samples classified by standard wear debris chemical rule classes. These classes indicate both metallic (Table 4) and non-metallic (Table 5) rules. Table 6 shows the most beneficial form of data collected via SEM/EDX. It not only offers the size and shape of each particle but also a chemical classification. This can be an invaluable tool for diagnosing engine wear because the user can consider both the size and chemical composition of the particles to determine what is happening inside the engine. For instance, in Table 6 a rule for a stainless-steel type of material (or 100Cr6) would be any particle with its highest component as iron greater than 70 percent, along with chro- mium greater than 1 and less than or equal to 3, manganese less than 1 percent, zinc and chromium less than 5 percent and tita- nium less than 3 percent. This, along with the second rule classification of 16MnCr5, indicates stainless steel and would suggest that some bearing wear is occurring, especially when considering the larger particle sizes. In comparing these results to the ICP data, chromium was not detected in any of the samples, including the second sample. When looking at the larger particles detected in the second sample, you can see that various steel (low and high alloy) and stainless-steel components (16MnCr5) are present at particle sizes larger than 50 microns. Again, wear debris of this size could signify significant engine wear. When examining the smaller sized particles in the second sample, you can see not only the stainless particles but also a significant amount of tin, nickel and chromium particles, which could be indicative of slight engine wear. These metals were not detected at all in the ICP data for the second sample. Ferrography results Direct-reading ferrography was also performed by the third- party laboratory for each of the samples. All three samples were found to have either light wear or moderate wear. No significant or abnormal particles were reported for any of the samples. Ferrous particles were between 5 to 15 microns in size for each of the three samples. Comparing this to the SEM/EDX data, there were numerous ferrous particles in each of the samples, with some as large as 50 microns in the second sample (Table 6). weAr deBrIs ANAlysIs 100Cr6 16MnCr5 Cr Cr Coating Cr-Ni-Mo Al203 Al-Alloy Al-Zn Brass Bronze CuSn Cu Fe-Cu High Alloy Steel Low Alloy Steel Low Fe Sn Steel Zn Coating Zn Misc. Zn-Cr Coating Zn-P Coating Ni Mn-P Coating Non-Ferrous Metal Sample 1 18 70 14 7 1 0 0 3 0 1 8 19 22 30 41 12 53 37 396 10 29 4 0 34 Sample 2 233 733 11 7 3 0 0 2 0 5 2 27 260 386 493 20 359 20 908 10 74 11 0 18 Sample 3 22 64 11 18 7 0 0 0 0 0 1 11 20 21 61 3 29 6 243 0 8 0 0 7 Table 4. Number of particles sorted by rule classification for metallic particles IrON COPPEr LEAD ALUMINUM TIN NICKEL CHrOMIUM TITANIUM VANADIUM SILVEr SILICON BOrON CALCIUM MAGNESIUM PHOSPHOrUS ZINC BArIUM MOLYBDENUM SODIUM POTASSIUM Sample 1 5 1 0 2 2 0 0 0 0 0 10 97 1,796 7 571 700 0 71 135 4 Sample 2 12 5 4 2 0 0 0 0 0 0 8 0 1,562 8 643 787 1 3 375 0 Sample 3 14 37 0 3 2 0 0 0 0 0 6 159 1,964 9 630 764 15 83 36 5 Table 3. Metal results (in parts per million) per sample via the third-party lab High Ca Ca Misc. SiAl Mineral Lubricants Mineral Mineral Fiber Misc. Misc. Salts SiAlCa Mineral Si-O/Si-C/Si-N Sample 1 82 1,078 86 84 1,694 121 64 151 223 221 Sample 2 9 2,707 4 204 354 214 12 975 11 18 Sample 3 24 633 5 41 233 51 7 50 10 13 Table 5. Number of particles sorted by rule classification for non-metallic particles