Roughness Measurement on Surfaces

The roughness of surfaces is an important parameter of surface topography. For many applications, it must be precisely defined so that a component has the desired properties and can fulfill its function. These can be the surfaces of seals as well as the sliding surfaces of spindles, ball screws, bearings and other fine mechanical components that should be particularly smooth. Other components, however, must have a minimum roughness so that, for example, cells can grow on implants. For some components, the surface parameters have an influence on the tribological properties. Roughness measurements in our laboratory can be performed on a variety of materials, such as metals, plastics, rubber, ceramics, polymers and many others.

Surface parameters can be recorded both two-dimensionally (line profile) and three-dimensionally. The raw data for the profilometry can be recorded either optically (e.g. white light interferometry, confocal microscopy) or mechanically (e.g. using the stylus method).

Tascon uses optical methods for roughness measurements in its laboratory. Optical profilometry uses various measurement methods of light microscopy and captures the topography of an entire area directly in three dimensions while avoiding contact with the surface. From this, surface roughness parameters of the surface topography can be determined. As a rule, line profiles along freely definable lines can also be derived and evaluated, so that the non-contact methods of optical profilometry have a wider range of uses than the mechanical tactile methods. Larger areas and inclined and curved surfaces can also be scanned.

Roughness measurements of surfaces are possible in the form of line profiles and as areal, three-dimensional roughness measurements. The evaluation of profilometric analyses is regulated by the standards DIN EN ISO 4287 for line profiles and DIN EN ISO 25178 for three-dimensional roughness measurements of surfaces. The parameters also define the parameters of roughness measurements. If filtering of line profiles (deconvolution of ripple and roughness) is necessary, this is carried out according to the standard DIN EN ISO 11562 / DIN EN ISO 16610-21.

In our laboratory for roughness measurements, we only use the modern and powerful contactless methods of optical profilometry such as confocal microscopy and interferometry (e.g. white light interferometry, WLI) for 2D and 3D analysis of the surface topography. For the standard-compliant evaluation of roughness measurements, we use powerful software packages with which the common surface parameters can be determined in accordance with the standard. Regular updates of the stored standards ensure evaluations according to the latest standards of profilometry.

The roughness analysis of dental implants is also part of our daily analysis in the laboratory, as the following example shows.