Surface finish

Surface finish, also known as surface texture or surface topography, is the nature of a surface as defined by the three characteristics of lay, surface roughness, and waviness. It comprises the small, local deviations of a surface from the perfectly flat ideal (a true plane). Surface finish, also known as surface texture or surface topography, is the nature of a surface as defined by the three characteristics of lay, surface roughness, and waviness. It comprises the small, local deviations of a surface from the perfectly flat ideal (a true plane). Surface texture is one of the important factors that control friction and transfer layer formation during sliding. Considerable efforts have been made to study the influence of surface texture on friction and wear during sliding conditions. Surface textures can be isotropic or anisotropic. Sometimes, stick-slip friction phenomena can be observed during sliding, depending on surface texture. Each manufacturing process (such as the many kinds of machining) produces a surface texture. The process is usually optimized to ensure that the resulting texture is usable. If necessary, an additional process will be added to modify the initial texture. The latter process may be grinding (abrasive cutting), polishing, lapping, abrasive blasting, honing, electrical discharge machining (EDM), milling, lithography, industrial etching/chemical milling, laser texturing, or other processes. Lay is the direction of the predominant surface pattern, ordinarily determined by the production method used. The term is also used to denote the winding direction of fibers and strands of a rope. Surface roughness, commonly shortened to roughness, is a measure of the total spaced surface irregularities. In engineering, this is what is usually meant by 'surface finish.' A Lower number constitutes less of these irregularities on the surface. Waviness is the measure of surface irregularities with a spacing greater than that of surface roughness. These irregularities usually occur due to warping, vibrations, or deflection during machining. Surface finish may be measured in two ways: contact and non-contact methods. Contact methods involve dragging a measurement stylus across the surface; these instruments are called profilometers. Non-contact methods include: interferometry, confocal microscopy, focus variation, structured light, electrical capacitance, electron microscopy, atomic force microscopy and photogrammetry. In the United States, surface finish is usually specified using the ASME Y14.36M standard. The other common standard is International Organization for Standardization (ISO) 1302.