Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/793941
the amount of wear debris considered normal always flags as exceptionally high at the lab. In addition, the AES test cannot fully account for particles larger than 3 to 8 microns, depending on the instrument used by the lab. "Big iron" machine components are much larger than normal, so the wear debris is larger as well. Simply put, the stan- dard tests didn't see the full picture. THE SOLUTION The solution was to develop machine-spe- cific test slates with custom alarm limits. This required a premium used oil analysis package. For the planetary gearcases, new oil samples for a baseline reference were sent to the lab. A test slate was assembled comprised of 21-element AES, viscosity, acid number, mois - ture by crackle test, oxidation by infrared (IR) and direct read (DR) ferrography (see the table on the right). The DR test was needed to overcome the particle size limitation with AES. While some labs do not offer the DR test, they can perform a particle quantity (PQ) index, which is a suitable alternative. Initially, the sample frequency on the four gearcases was weekly so the data density could be increased and what was "normal" could be identif ied. The mainte - nance teams thought this was overkill, WEAR ELEMENTS NEW OIL REFERENCE TYPICAL USED OIL Iron ppm 13 100-300 Chromium ppm 0 0-1 Molybdenum ppm 0 0 Aluminum ppm 0 0-2 Copper ppm 0 0-2 Lead ppm 0 0 Tin ppm 0 0 Silver ppm 0 0 Nickel ppm 0 0 Vanadium ppm 0 0 Titanium ppm 0 0-1 Manganese ppm 0 0 Cadmium ppm 0 0 Contaminant Elements Silicon ppm 19 0-20 Sodium ppm 0 0-2 Boron ppm 1 2 Additive Elements Magnesium ppm 7 6-8 Calcium ppm 5 6-8 Barium ppm 0 0 Phosphorus ppm 185 185-220 Zinc ppm 2 2-10 Non-Metallic Content Water % vol. Nil Nil Solids % vol. <0.1 Not tested Lube Data Viscosity at 40°C cSt 318.0 Alarm at ±10% Acid Number mg KOH/g 0.85 1.2 Infrared Hydroxy N/A 0 Anti-wear Loss N/A 0-1 Oxidation N/A 0-11 Nitration N/A 5 Oxidation/Sulfate N/A 30 Additional Tests PQ Index 9 30-80 COVER STORY A customized test slate for "big iron"