Even smooth surfaces are full of microscopic imperfections. These play a crucial role in engineering because they affect the functionality of components. The so-called roughness power spectrum is often used to analyse technical surfaces and optimise their properties. It is based on the superposition of wave functions and allows the determination of important roughness parameters such as Rz and Ra. Scientifically, the roughness power spectrum provides valuable information for contact-mechanical analyses thanks to the multi-scale consideration of all wavelengths. Finally, the invisible world of surfaces becomes usable.

The complete measurement of hydrodynamic lubrication film pressure in both axial and circumferential directions is a key element in validating hydrodynamic journal bearing models. For this purpose, we employ an innovative measurement system that integrates piezoelectric pressure sensors directly into the shaft. During operation, the bearing is loaded and moved over the sensor, allowing for full-field pressure acquisition across the entire lubrication contact – under realistic conditions and with high temporal and spatial resolution. Measurements are taken in 0.45° increments at rotational speeds of up to 18,000 rpm, corresponding to a circumferential speed of approximately 100 m/s.

This method is particularly valuable for assessing the influence of compliant bearing surfaces, such as polymer-based running layers. These materials often result in a more uniform pressure distribution within the lubrication film. However, under certain operating conditions, they may also lead to edge-loading phenomena, which can promote bearing failure.

Thanks to the ability to fully capture the pressure distribution during operation, even plastic deformations – such as the flow of white metal – can be detected and analyzed. This opens up new possibilities for the design, optimization, and durability assessment of modern journal bearing technologies.

A small number of IKAT representatives were invited to the Institute for Machine Elements and Machine Design as part of the Project Committee Shaft-Hub-Connections of the Research Association for Drive Technology (FVA) in Dresden. In addition to the final reports, proposed topics and research proposal ideas, the status of ongoing research projects was also successfully presented. Among other things, Mr Ebermann presented the status of the ‘Press bracing in high-speed electric machines’ project, which also includes the development, design and implementation of a high-speed test bench. The first test run of the test bench is shown in the following video. At the bottom left of the video, the target and actual speed can be seen alongside the static torque curve.