Abstract
Wear is a complex process which may take many forms and this paper describes some methods for its study which have been used in engineering research in the hope that the principles involved may be suitable for more general application.
Measurement of change in size or shape is usually the most profitable but, in view of the small changes in dimension often involved, great care is necessary. The principles of engineering metrology are introduced and the advantages of ‘air gauging’ are outlined.
Estimation of the amount of wear is difficult because the changes are often very small compared with the total weight of the component subjected to a wearing process. Particular care is necessary to avoid false conclusions attributable to changes in weight caused by water absorption, etc.
Another fruitful method relies on providing some form of witness; for example, a diamond pyramid hardness impression may be made in the unworn surface so that its change in size can be used to estimate the extent of wear.
Stylus instruments have much application in wear studies, providing the simplest means for quantifying the texture of a surface.
The optical microscope is an invaluable tool for wear studies, particularly if adapted for microhardness testing and interference methods.
The paper concludes with a reference to electronic methods of surface study, particularly the electron microscope and the electron probe analyser.
Get full access to this article
View all access options for this article.