Martial Wüthrich
Managing Director
Diavite AG

“The special thing about rollers is that the measurement has to be made in the radial direction and not, as is usually the case and easier, in the axial direction. Therefore, the development of rollDetect became necessary. It enables the simple positioning on the roll crosswise to the roll axis and thus reliable, always constant measuring results.”

Martial Wüthrich heads the Swiss company Diavite AG for almost 20 years. Since 2009, the trained precision mechanic has also been the owner of Diavite AG. The company has been manufacturing roughness measuring instruments since 1953 and has consistently improved and developed the technology ever since. Diavite AG is based in Bülach/Switzerland and works with numerous suppliers. The assembly is carried out by a small team in Bülach and the instruments are sold all over the world.

As a specialist in the field of surface measurement, Diavite AG has developed a wide range of stylus for the most diverse applications. There are stylus for measurements on the inside of bores, on bottom surfaces or inner flanks of bores or grooves, of cutting edges and contours, of tooth flanks or axes as well as transverse and depth probes. A particularly sophisticated design is a circumferential stylus for balls, tubes or shafts, whose mechanics follow the surface of the test piece in such a way that the probe tip always remains radially oriented to the curvature of the surface to be tested. The know-how acquired in solving such tasks enables the company to develop and supply tailor-made sensors even for very unusual tasks. This flexibility also applies to the development of adapted evaluation software.
Martial Wüthrich, the Diavite AG has been producing devices for measuring surface condition for many years. What has changed since then with regard to the requirements for these special measuring devices?
Above all, the evaluation electronics have been improved. Thanks to various features, the measurement results are displayed faster, more accurate and are more user friendly. Of course, the standards have also changed during this time and the scanning of the surface had to be adapted accordingly.

Are there fundamental differences within the family of probing instruments for measuring surface roughness?
In tactile measurement, we distinguish between two measurement methods. For portable measuring devices, we use mostly skid probes. The runner on the probe forms the reference against which the diamond measures. A mechanical filter is therefore used. The second measuring method is the version with a free stylus, i.e. the measurement with an external reference. In this case, only a tripod can be used, since the guide in the feed forms the reference for the diamond. With this method it is possible to measure not only the roughness, but also the contour and profile.

Diamont stylus or needle stylus? Which version for which application?
For manual measurements, only the diamont stylus comes into question. In the workshop, we try to use diamont stylus if possible, since the skid arm is protected with these stylus and the stylus is therefore less sensitive to incorrect manipulation. Of course, it is also a question of space.

Can the surfaces of all kinds of bodies and materials be measured?
Due to the variety of our probes, a great many surfaces can be measured on a wide variety of materials.

What about smooth and corrugated rollers?
With smooth rollers, we can measure the roughness with a diamont stylus. With corrugated rolls we no longer talk about roughness, here the contour profiles have to be measured. With a needle stylus this measurement is possible with the same device.

Does this mean that such measuring devices can also be used in the milling industry?
Yes, with the rollDetect, which we developed together with the company Bühler, both the roughness (RA value) on smooth rolls and the corrugation profiles can be measured and evaluated with one instrument. With this tactile solution, which only requires replacement of the probe, measurements can be taken quickly and accurately in the machine without removing the rolls. Since the tactile measurement is not influenced by external light influences, the rolls can be measured regardless of whether they are exposed to sunlight or standing in a dark room.

Martial Wüthrich: "The rollDetect roll measuring system developed by us together with Bühler is easy to use and yet works very accurately.

Are there special specifications for the surface measurement of rollers?
The special thing about rollers is that the measurement has to be made in the radial direction and not, as is usually the case and easier, in the axial direction. Therefore, the development of rollDetect became necessary. It enables the simple positioning on the roll crosswise to the roll axis and thus reliable, always constant measuring results.

Do you need specialists for roughness measurement of rolls? Or can this also be carried out by laymen?
The measurement itself is easy to carry out, since a clean profile is required above all. The handling requires a little bit of tact, since we measure in the micrometer range (1/1000 mm). Since the measurement is automated after the start signal, it can be carried out by anyone. However, in order to use the full potential of the technology and to benefit from the experience and expertise to optimize the roll and process technology, it is recommended to have these measurements carried out by an experienced, skilled specialist or a service technician!