Wear Debris Analysis
Particles in oil arise from a number of different sources. Contamination can enter the system during maintenance, through breathers, during oil top offs, in the course of oil changes, and in other ways. Wear particles are generated during machine operation. These wear particles can be caused by contamination, improper lubrication, a change in operating conditions, and other factors that may cause metal-to-metal contact.
ALS Tribology provides various levels of wear debris analysis, a process by which wear particles in a lubricant are identified and used to assess the condition of equipment. As wear particle sizes and quantities increase, so does the risk of failure due to wear. Wear debris testing evaluates particles that may be too large to be detected in the standard metals test. This adds another dimension to the information received from routine testing. Wear debris analysis identifies the properties:
- Normal rubbing wear
- Severe rubbing wear
- Cutting wear / abrasives
- Fatigue wear
- Laminar wear
- Fatigue spheres
- Dark metallo-oxides
- Red oxides (rust)
- Corrosive wear
- Ferrous metals-iron and iron alloys
- Non-ferrous metals
- Nonmetallic particles
- Friction polymers
- Fibers
- Contaminants, such as dirt, coal dust, fly ash, fibers, etc.
Direct Reading Ferrography differentiates between large (>5 microns) and small (<5 microns) ferrous (iron) particles in a given machine. The data is used for trending purposes and to indicate abnormal wear. When an abnormal increase is detected, Analytical Ferrography is typically used to identify and assess the wear mode. On critical equipment, this information is invaluable.
Analytical Ferrography is a comprehensive and detailed microscopic analysis of the solid particles that are captured in the oil sample. The analysis begins by determining if metal particles are ferrous or non-ferrous. ALS can also heat treat the particles to determine the metallurgical composition. Particles such as fibers, corrosive wear, sand, dirt, and other elements are identified. Depending on the types of particles, the quantities, and their respective sizes, ALS can determine the abnormal wear mode, identify the likely component, detect the wear mechanism(s) generating the particles, and assess the potential for failure. Detailed photographic images of the problem particles are included with the report.
Laserview™ is a streamlined, cost effective wear debris analysis service used in combination with traditional oil analysis as a trending tool and to pinpoint severe wear conditions. This test data complements other oil analysis techniques by using laser imaging and advanced image process software to classify, identify, and measure type of wear mechanism, particle size distribution, rate and severity of wear processes, and ISO particle count.
Some of our ALS Tribology laboratories employ Lasernet Fines instrumentation, which was developed by Lockheed Martin with the Naval Research Laboratory for military application. Using direct digital imaging, Lasernet Fines test results classify particles larger than 20 micron into cutting wear, severe sliding wear, fatigue wear, and nonmetallic material. The analysis economically combines features of particle count determination with quantifying wear particle classification for industrial, gear and drivetrain components without subjective interpretation.
The test data complements other wear analysis techniques by using laser imaging and advanced image processing software to identify and measure:
- Type of wear mechanism
- Rate and severity of wear processes
- Wear particle size distribution
- Particulate contamination and oil cleanliness
Filter Patch Test (FPT, filtergram, or patch test) is a common method for making a detailed determination of wear occurrence, especially for non-ferrous materials, by examination of wear particles through a microscope. A measured portion of used oil is filtered through a filter patch. Trapped wear particles and debris are then visually examined microscopically for a qualitative report. Observation will generally be accompanied by a photo of the filtered wear material on a test report. The debris is assessed and the particles graded. The FPT can tell us a number of things:
- Is there abnormal wear taking place?
- Is the wear ferrous or non-ferrous?
- Is there any evidence of abrasive contaminants e.g. dirt?
Particle Quantifier Index (PQI): The Particle Quantifier is a magnetometer that measures the mass of ferrous wear debris in a sample and displays this as a PQ Index. Test results are quantitated as a relative number of ferrous materials within a sample; this can then be trended for useful wear monitoring. PQI is a simple, cost-effective test that can easily be incorporated into routine trending analysis.
Visit the download section of our site to learn more about this service as well as the many other testing and analyais services offered by ALS Tribology.
