Measurement technology service

Roughness measurement is a measurement method used in the field of surface metrology to determine the specific properties of a material surface. These properties are significantly influenced by the manufacturing process. For example, regular (periodic) surface structures are created during turning, milling or drilling and irregular (aperiodic) surface structures during rolling, casting or grinding. Machine settings or the tool itself (wear) also have an influence on the surface structure.

In order to be able to assess surfaces in a repeatable manner, special test methods must be used. The most common measuring method is the mechanical stylus method, in which the surface is scanned with a particularly hard stylus tip. Alternatively, non-contact optical measuring systems, such as the optical coordinate measuring machine, are also used, which can be supplemented by acoustic or electromagnetic methods.

Roughness measurement is crucial for functional characterization and quality assurance. The measuring section is often precisely defined and analyzed in order to achieve precise results. In addition to roughness measurement, flatness measurement is also of great importance, especially for the topography representation of the surface. This can be supported by optical methods that enable detailed micrographs.

For this purpose, we carry out optical and tactile roughness measurements in accordance with DIN EN ISO 21920 to ensure high quality and repeatability of the measurement results.

Our 3D service, coordinate measuring technology, describes the individual measuring points on the workpiece surface using coordinates. This means that they are represented as unique positions on the axes of a Cartesian coordinate system. These measuring points can be used to calculate control geometries, such as diameters and straight lines, which can be related to each other by the measuring device in order to generate a virtual image of the workpiece.

These measuring points are recorded by tactile or optical sensors. 3D measurement technology includes both tactile and optical sensors. Although the absolute accuracy of tactile sensors is very high, the surface must be mechanically scanned point by point, which means that long measuring times are required with high data density. In contrast, optical measurement technology enables complete surfaces to be captured quickly, making optical measurement more efficient. This allows construction data to be digitally reconstructed from the measurement points.

Modern coordinate measuring machines offer great flexibility through the integration of additional sensors, allowing the various advantages of the sensors to be combined. For example, white light sensors based on the principle of chromatic aberration can also be used for surface measurements. An optical profilometer, which functions as an imaging measuring device, enables precise optical microscope images and the detailed image composition of surface structures.

A wide variety of requirements can be met by using different illumination systems. Transmitted light illumination is particularly suitable for measuring edges and openings. Bright field illumination in incident light is carried out using the same lenses that are used for image generation, which is why these illuminations are also referred to as coaxial. Smooth, horizontal surfaces appear brighter. Dark field illuminators in incident light are mounted concentrically to the optical axis in a ring-shaped arrangement. This means that the light cone is not illuminated on the inside, which is how the term dark field is derived. Smooth, horizontal surfaces appear darker, making the illumination suitable for highly reflective materials as well as for the detection of surface defects.

In addition to optical profilometers and light microscopes, 3D coordinate measuring machines and raster scanning techniques can also be used to carry out precise measurements and analyze complex surface structures. Rotational workpieces can also be measured by using rotary and swivel axes.

Leak testing with helium is one of the most precise methods for measuring the smallest leaks. This technology is therefore primarily used in sensor technology and electromobility, for example when sensitive measurement technology in a gas-tight encapsulated housing or the tightness of bipolar plates needs to be tested. A leak detector can be used to determine both integral leakage rates in a test chamber and the exact location of the leak using the so-called sniffer test. With this method, even larger components can be tested efficiently and precisely using the sniffer probe.