Surface finishes - Measurement

This document is to be read following the file .

The files and [R 1 231] present, in a non-exhaustive way, the currently accepted knowledge in the field of surface characterization, based essentially on a bibliographical study and the author's experience.

In today's industrial world, :

• plans with parameters corresponding to the old standards (different definitions depending on the country of origin);

• older-generation equipment (parameters following older standards with more standardized signal processing) ;

• plans and equipment that comply with current standards, but which few people use properly;

• equipment for three-dimensional surface characterization, with different treatment methods;

• pre-standard surface parameter documents.

This situation is due to recent developments in standardization, the development of equipment and the increased performance of hardware and software.

Three-dimensional microgeometry is currently the most accurate way of characterizing a surface. It enables irregularities to be observed, identified and quantified. It also enables studies to be carried out into the correlations between microgeometry and the function or behavior of a surface. In particular, these studies should make it possible to specify or redefine the limits between the various geometric deviations (shape, waviness and roughness), whether on a profile or on a surface. Indeed, while some functions require these geometric deviations to be taken into account separately, others require them to be characterized more globally (for example: shape + waviness or waviness + roughness or shape + waviness + roughness).

Historically, surface condition has been assessed visually and/or tactilely, then measured on a profile using sensors with varying degrees of signal processing (profilometry), and finally measured on part of the surface (topography). Three-dimensional techniques are no longer the preserve of research laboratories. Prototypes have become industrial equipment found in the laboratories of companies and service firms. We can imagine that, in terms of equipment, the next steps will be the three-dimensional measurement of surface conditions in production and the integral measurement of an entire surface (macro, microgeometry, either separately or globally).