Beyond Particle Counting - Automatic Wear Classification
The LaserNet Fines is a bench-top analytical instrument that combines the oil analysis techniques of particle shape classification (basic ferrography) and particle counting in one instrument. It analyzes hydraulic and lubricating oil samples from various types of equipment and machinery that are part of a machine condition monitoring program. The monitoring is based primarily on the morphological (ferrography) analysis and the particle size distribution of the abnormal wear particles that are created from the internal components of the machine. The operator is presented with an assessment of particles found in the fluid sample and a history of previous results for the same equipment. The LaserNet Fines can be used as a stand-alone analytical instrument, or in conjunction with a full service oil analysis program.
As a particle shape classifier, the LNF provides the user with shape recognition of all particles greater than 20 μm. An algorithm sorts particles into the following categories: cutting, fatigue, severe sliding, nonmetallic and fibers. The shape recognition software will also test for bubbles and water droplets greater than 20 μm are eliminated from the particle counting results. The instrument is also capable of giving approximate results of free water based on this feature.
The LaserNet Fines was designed primarily as an automatic wear particle shape classifier and trending tool to assist in condition monitoring programs. However, because of its direct imaging capability it is also an accurate particle counter. It is ISO 4406:1999 compliant.
As a particle counter, the LaserNet Fines processes and stores thousands of images to obtain good counting statistics. Particles are sized directly and results can be displayed by ISO Code (>4 μm, >6 μm, and >14 μm), or other codes such as the NAS Code (5-15 μm, 15-25 μm, 25-50 μm, 50-100 μm and >100 μm). The direct imaging capability of this instrument eliminates the need for calibration with a test dust. Air bubbles greater than 20 μm are ignored and the laser is powerful enough to process heavily sooted (black) oils.
Shape features were chosen to give optimal distinction between the assigned classes of fatigue, cutting, severe sliding, nonmetallic, fibers, water bubbles, and air bubbles. An extensive library of particles, which were identified by human experts was used.
It is noteworthy that the LaserNet Fines correctly counts the NIST SRM 2806 (or its derivative, the commercially available PartiStan) this is the calibration fluid for the ISO11171. The LaserNet Fines correctly measures the SRM 2806 because it is an automated microscope calibrated to a known linear dimension, a much more fundamental calibration than using an arbitrary calibration fluid. The LNF directly images each particle whereas an automated light blockage particle counter measures only how much light is blocked. In essence, the LNF achieves the same counts that the NIST did for the SRM 2806 from first principles.
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