The concept of a virtual roughness tester

For the calibration of roughness testers various methods are available which are prescribed in international standards [1,2]. However, from a calibration of a roughness tester it is not evident what the uncertainty will be in a measured roughness of a product, with a deliberate roughness profile. On the other hand, international standards require that for a proof of the conformance to specifications, the measurement uncertainty must be taken into account (ISO 14253-1 [3]). In principle it is possible to vary all measurement conditions by experiment (stylus tip diameter, measuring force) to estimate the influence of the uncertainty of these measurement parameters on the calculated roughness parameter [4,5]. This however requires many different measurements for each sample and this cannot be demanded of shop-floor measurements. To solve this problem, the concept of the virtual roughness tester is proposed, where a measured roughness profile is re-calculated many times with varying measurement conditions so that for each parameter a complete uncertainty evaluation is made which satisfied all requirements of e.g. the GUM or EAL-R2 [6].