5.1 Generic approach

Relating surface texture to performance, here called function, has always been difficult. This is because the key ingredients of tribology, surface instrumentation, random process analysis and digital analysis all evolved at about the same time in the late 1950s and throughout the 1960s. As a consequence of this simultaneous development, some good instrumentation was not backed up properly with good theory. The development has been uneven and has resulted in a lack of structure.

Probably the biggest problem has been a lack of focus when discussing function. This has been due to two reasons. The first is the fact that the number of applications where surfaces are important is so large and diverse that a systematic approach has been impossible. The second is that in many cases where a relationship between the surface and function has been found, the link has been suppressed due to confidentiality. For these reasons, a generic approach is given here to provide a guide. A major aspect of this approach is the classification of the function into a simple format. Obviously, no classification can cover all functions but the approach here has been to classify tribological applications and in particular, contact, friction, wear, lubrication and failure mechanisms. These make up the bulk of engineering functions.

The characterization of function, as indicated earlier, has been broken down into two variables.

1. The normal separation of two surfaces.

2. The lateral relative velocity of the two surfaces. Some of the tribological functions are indicated in...