Wear Debris Analysis

"Trend Analysis is the process by which a change in machine condition is determined from an examination of changes in specific sensors or output.

"Different systems exhibit different trends. For instance, the wear debris generated from a system involving gears and bearings may well be quite high initially, particularly if no attempt has been made to 'run-in' the system. Thus there is a gradually reducing level of debris until the system settles in. Then comes the acceptable very low wear rate associated with well lubricated surfaces, which perhaps increases just slightly. Finally, the machine begins to show signs of fatigue or fracture and particle generation increases at an ever increasing rate. These three stages of wear are shown in the classical 'Bath-tub" curve.

"Another changing feature of wear with time, is that the wear rate begins to fluctuate. After the 'running-in' period, the wear rate is expected to be reasonably uniform, although it may rise slightly. However, as conditions begin to become less favourable wear may be less or more in terms of particle size generation as well as with total quantity. Scatter is thus seen as a trend indicator.

"The third sort of trend indication is that associated with the shape of particle - its morphology. This is less easy to measure than the gravimetric level or 'size' of particulate; but, by using the analysis mentioned later in this chapter for defining particle shape, two or more possible specific indicators of shape may be trended to detect the point at which a serious change in debris particle shape occurs."

Introduction to wear debris Analysis
Introduction
Overall View of Methods
Choice
Type of Connection
Type of Preparation
Type of Analysis
Scope

Basic Concepts and Theory
Quantity and Size
Trend Analysis
Absolute Levels
Visual Identification-Shape
Systematic Particle analysis
Wear and wear particles
Wear particle atlas (WPA)
Computer-aided systematic particle analysis (CASPA)
Computer-aided vision engineering (CAVE)
Composition
Origins
Spectometric Identification

Practical Issues
Sampling
Position
Preparation
Time
Grease
Analysis
In-line and on-line analysis
Off-line analysis
Reporting

Equipment and Instrumentation
Sampling points and probes
Sample points
Sample probes
Samplers
Patch Making
On-line conpar
Off-line Millipore
Patch Analysers, Including image analysis
Comparative analysis
Automatic analysis
Image analysis
Wear debris atlases
Off-line Debris Detectors, including ferrography
Ferrous debris
All metal debris
All debris
Off-Line particle analysers, including counters
Optical
Acoustic Spectroscopy
In-Line Debris Detectors
Magnetic/conductance
Magnetic/inductance
Thin Film Wear and Radioctivation
Mesh/Conductance
In-Line Particle Analysers, including counters
Inductance
Ultrasonics
On-Line Debris Detectors
Electrical conductance
Magnetic attraction
Optical time of transition
Thin film wear
On-Line Particle Analysers, including counters
Filter blockage
Inductance
Optical obscuration
Ultrasonics
Spectrometry
Kits

Applications and Case Studies
Applications
General Comments
Appropriate systems and machinery
Why wear debris analysis is so successful
Case Studies
Experimental testing
Individual tests
In-line metal detection using the ODM
Comparitive tests
Loaded bearing rig, using vibration, temperature, spectroscopy, ultrasonics and
WDA
Industrial use
Individual tests
Marine gear box using the MPD
British Rail rolling stock using spectroscopy
1000 ton press using the CSI Oil View
Hydraulic robot using filter blockage
Marine diesel engines using Ferrography
Comparative tests
Coal mill gearboxes using vibration, oil analysis and WDA
Gear drive of a cement plant mill using vibration and WDA (RPD)

Buyer's Guide
Companies (including oil analysis)
Equipment & Instrumentation
Services, Laboratories, Consultants, & Training

Reference
Glossary of Terms
Tables
Compatibility of membrane filters with liquids
References
Bibliography