Automotive & Aerospace
In the sector of automotive & aerospace, the demands on products are particularly high and subject to strict standardisation systems. Surface characteristics determine not only functionality, but also have a crucial part to play concerning wear. The behaviour of emissions and acoustics are also dependent on consistent surface quality in the sub-µ range. In order to evaluate contours and micro-structures in a meaningful way, automobile suppliers use touchless optical measuring technology from Confovis.
Fast surface scanning provides extensive 3D data
Many modern surfaces for vehicle components are coated to meet increasing requirements. The typical coats such as DLC (diamond like carbon), MoN (molybdenum coating) or ta-C (tetrahedral amorphous carbon coating) require areal measurements of the surfaces because they have randomly distributed structural elements.
Areal measurement is needed in order to quantify the results of the precoating and post-coating of surfaces. It is important that the quality of the measurement is good enough to exclude any artefacts. Compared with other confocal measurement techniques, typical of the robust “structured illumination“ technique is that the coated surfaces contain no artefacts and the transfer of the profile-based parameters of DIN EN ISO 4287 and DIN EN ISO 13565 to the area parameters of DIN EN ISO 25178 is possible.
Contour and roughness measurements, target/actual comparison, wear analysis
For example, the Rz and the Rpk value can be reconciled to the areal parameters S10z and Spk by the MountainsMap analysis software, which makes tactile measurements suitable as basis and reference. Besides, Mountainsmap, for example, can count droplets and compare tribological properties of surfaces via threshold filters. In the same way, frequency analyses can be made and texture directions determined. To Confovis, traceability of own measurements to the ”gold standard“ of stylus profilometers is of significance.
Non-destructive measurements by combined optical measuring technique
Most different measurement tasks can be solved by the combined technique of confocal measurement and focus variation in one measurement system. Outlines involving large angles can be measured by focus variation. Roughness is captured by the Confovis measurement systems with the patented confocal measuring technique of structured illumination. In this way, micro-geometries as well as roughness can be measured on reflecting surfaces to the accuracy of a few nanometers and are traceable to any standard.
Variations on confocal measurement technology
The measuring methods of focus variation and the confocal measuring technique based on the working principle of Structured Illumination both have contrast analysis as a foundation and work without interferograms. In contrast to conventional confocal microscopy, no rotating pinhole disk or other moving mechanical components such as scanner mirrors are used in the scanning process. The required accurate depth selection is instead guaranteed by the depiction and following evaluation of a sequence of illuminations patterns in the focal plane. A special static mask which coordinates the rays of the quickly shifting light sources is responsible for this. The contrast value is determined by the CCD sensor both in the confocal mode and during focus variation measurement. The contrast difference evaluates the out-of-phase sequences confocally.
Roughness measurements on components – standardised and traceable
Roughness measurements with the traditional roughness parameters Ra, Rq and Rz in accordance with DIN EN ISO 4287/4288 as well as DIN EN ISO 13656 can be taken in a way that is traceable according to the roughness standards certified by the National Metrology Institute of Germany (PTB). Here, Confovis measurement devices achieve a high degree of precision and provide the user with excellent comparability to conventional systems. The measurement surface of the roughness standards consists of ground and precision turned irregular profiles. This way, the standard has a broad spectrum of surface variations that can be found in practice. The basis for the surface roughness values can be derived from the Rpk, Rvk and Rk values and a transition to DIN EN ISO 25178 can be formed as well.