Karedusastmed

Karedusastmed is a term used in Estonian to describe the degree of surface roughness of a material’s surface. It characterizes how much the actual surface deviates from an ideal smooth plane, caused by manufacturing processes such as turning, milling, grinding, or forming. The concept is important in many technical applications because surface roughness can influence friction, wear, sealing, fatigue life, and appearance.

Measurement and representation of karedusastmed is typically done with profilometry. The most common parameter is Ra, the arithmetic mean roughness, but additional parameters such as Rz (mean peak-to-valley height) are also used. In modern practice, areal roughness parameters are increasingly employed, including Sa and Sz. Measurements can be performed with a contact stylus or non-contact optical methods. Results are usually expressed in micrometers (µm), and for very smooth surfaces, in nanometers. Generally, lower karedusastmed values indicate smoother surfaces.

Standards and usage: In GPS/ISO standardization, karedusastmed is defined and quantified according to established terminology and parameters. It is commonly specified in engineering drawings and contractual requirements to ensure proper fit, sealing, lubrication, or tribological performance. The value depends on material, tooling and processing conditions, surface treatment, and finishing operations, and it is often controlled through process parameters and quality control routines.

Karedusastmed thus serves as a key descriptor of surface finish in Estonian technical literature and industry, linking manufacturing methods to the functional performance of components.