érdeség

Érdeség is the Hungarian noun for the roughness or coarseness of a surface. In technical use it denotes the textured irregularities of a material relative to an ideal smooth plane. It encompasses microscopic asperities and larger-scale texture that influence how a surface interacts with other materials and the environment.

Roughness is scale-dependent and is quantified with parameters such as Ra (arithmetical mean roughness), Rz (mean peak-to-valley height) and other indices. Measurements are performed with contact stylus profilometers or non-contact optical methods, and results are typically given in micrometres or nanometres. Areal roughness is addressed by ISO 25178.

Causes include manufacturing processes—machining (turning, milling), grinding, casting, and forming—as well as wear and corrosion. Techniques to modify érdeség include finishing operations that reduce roughness, such as grinding, polishing, lapping, or burnishing, or, conversely, roughening processes (érdesítés) intended to improve adhesion, bonding, or tribological performance.

Érdeség affects friction, wear, coating adhesion, fatigue life, sealing effectiveness, and visual appearance. In design and manufacturing, controlling roughness is a common aspect of quality assurance and performance optimization across metals, polymers, ceramics, and composites.

Etymology: the word derives from érdes, rough, with the suffix -ség forming a noun indicating a quality or state.