Ra measurement

Ra, or roughness average, is a measurement used to quantify the surface texture of a material, such as metal, wood, or concrete. It represents the average height of the surface irregularities or bumps, calculated by measuring deviations from a mean line across a sample. A lower Ra indicates a smoother surface, while a higher Ra indicates a rougher one. This measurement helps determine surface quality, friction, and how well parts will fit or function together in engineering and manufacturing applications.