ASTM-D7684:11(R2020) pdf free download – Standard Guide for Microscopic Characterization of Particles from In-Service Lubricants.
An increase in particle concentration, accompanied by an increase in size and severity of particle types. is indicative of initiation of a fault. This guide describes commonly found particles in in-service lubricants, but does not address methodology for quantification of particle concentration.
5.2 This guide is provided to promote improved and expanded use of particulate debris analysis with in-service lubricant analysis. It helps overcome some perceived complexity and resulting intimidation that effectively limits particulate debris analysis to the hands of a specialized and very limited number of practitioners. Standardized terminology and common reporting formats provide consistent interpretation and general understanding.
5.3 Without particulate debris analysis. in-service lubricant analysis results often fall short of concluding likely root cause or potential severity from analytical results because of missing information about the possible identification or extent of damaging mechanisms.
5.4 Caution shall be exercised when drawing conclusions from the particles found in a particular sample, especially if the sample being examined is the first from that type of machine. Some machines, during normal operation, generate wear particles that would be considered highly abnormal in other machines. For example, many gear boxes generate severe wear particles throughout their expected service life, whereas just a few severe wear particles from an aircraft gas turbine oil sample may he highly abnormal. Sound diagnostics require that a baseline, or typical wear particle signature, be established for each machine type under surveillance.
6. Reagents
6.1 Use reagents of type and purity following specifications from the manufacturer of the wear debris analysis sample preparation apparatus. Use reagents and solvents that do not contribute significant particles to the sample.
7. Procedure
7.1 Particulate matter extracted from in-service lubricants are displayed on a relatively flat surface such as a filter patch, glass slide, or other substrate for microscopic inspection. The procedure normally involves the following steps. These steps may he performed in this order or in a different order, and steps may he added as needed. This guide applies to interpreting microscopic observations (7.1.6) and reporting results (7.1.7) but does not address steps 7.1.1 — 7.1.5.
7.1.1 Collecting or concentrating particulate matter,
7. 1.2 Depositing it on a surface to produce a specimen suitable for placement on an optical microscope stage,
7.1.3 Removing residual in-service lubricant fluid from the specimen,
7.1.4 Transporting the specimen to a microscope stage,
7.1.5 Using the microscope to inspect the specimen.
7.1.6 Interpreting observations, and
7.1.7 Recording results.
7.2 Use a desired particulate extraction technique to prepare a specimen for microscopic wear debris analysis. Specimens arc prepared using an apparatus that effectively extracts solid particles trom liquid samples and deposits the particles on a relatively flat supporting surface that can be placed on the viewing stage of an optical microscope.
7.3 Prepare specimens using one of the following particle extraction techniques:
7.3.1 Analytical ferrography using ferrograph to produce linear glass slides in accordance with Practice D7690.
7.3.2 Analytical ferrography using ferrograph to produced rotary glass slides,
7.3.3 Filter patch analysis using filter patch makers.
7.3.4 Filter debris analysis.
7.3.5 Magnetic plug inspection.