Surface roughness in the context of Waviness

A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or the directions of the loads (forces) applied to the parts.

The term "bearing" is derived from the verb "to bear"; a bearing being a machine element that allows one part to bear (i.e., to support) another. The simplest bearings are bearing surfaces, cut or formed into a part, with varying degrees of control over the form, size, roughness, and location of the surface. Other bearings are separate devices installed into a machine or machine part. The most sophisticated bearings for the most demanding applications are very precise components; their manufacture requires some of the highest standards of current technology.

Roundness is the measure of how closely the shape of an object approaches that of a mathematically perfect circle. Roundness applies in two dimensions, such as the cross sectional circles along a cylindrical object such as a shaft or a cylindrical roller for a bearing. In geometric dimensioning and tolerancing, control of a cylinder can also include its fidelity to the longitudinal axis, yielding cylindricity. The analogue of roundness in three dimensions (that is, for spheres) is sphericity.

Roundness is dominated by the shape's gross features rather than the definition of its edges and corners, or the surface roughness of a manufactured object. A smooth ellipse can have low roundness, if its eccentricity is large. Regular polygons increase their roundness with increasing numbers of sides, even though they are still sharp-edged.

Frost is a layer of ice on a solid surface, which forms from water vapor that deposits onto a freezing surface. Frost forms when the air contains more water vapor than it can normally hold at a specific temperature. The process is similar to the formation of dew, except it occurs below the freezing point of water typically without crossing through a liquid state.

Air always contains a certain amount of water vapor, depending on temperature. Warmer air can hold more than colder air. When the atmosphere contains more water than it can hold at a specific temperature, its relative humidity rises above 100% becoming supersaturated, and the excess water vapor is forced to deposit onto any nearby surface, forming seed crystals. The temperature at which it will form is called the dew point, and depends on the humidity of air. When the temperature of the air drops below its dew point, excess water vapor is forced out of solution, resulting in a phase change directly from water vapor (a gas) to ice (a solid). As more water molecules are added to the seeds, crystal growth occurs, forming ice crystals. Crystals may vary in size and shape, from an even layer of numerous microscopic-seeds to fewer but much larger crystals, ranging from long dendritic crystals (tree-like) growing across a surface, acicular crystals (needle-like) growing outward from the surface, snowflake-shaped crystals, or even large, knifelike blades of ice covering an object, which depends on many factors such as temperature, air pressure, air motion and turbulence, surface roughness and wettability, and the level of supersaturation. For example, water vapor adsorbs to glass very well, so automobile windows will often frost before the paint, and large hoar-frost crystals can grow very rapidly when the air is very cold, calm, and heavily saturated, such as during an ice fog.

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.

Tube cleaning describes the activity of, or device for, the cleaning and maintenance of fouled tubes.

The need for cleaning arises because the medium that is transported through the tubes may cause deposits and finally even obstructions. In system engineering and in industry, particular demands are placed upon surface roughness or heat transfer. In the food and pharmaceutical industries as well as in medical technology, the requirements are germproofness, and that the tubes are free from foreign matter, for example after the installation of the tube or after a change of product. Another trouble source may be corrosion due to deposits which may also cause tube failure.

A grinding machine, often shortened to grinder, is any of various power tools or machine tools used for grinding. It is a type of material removal using an abrasive wheel as the cutting tool. Each grain of the abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation.

Grinding as a type of machining is used to finish workpieces that must show high surface quality (e.g., low surface roughness) and high accuracy of shape and dimension. As the accuracy in dimensions in grinding is of the order of 0.000025  mm, in most applications, it tends to be a finishing operation and removes comparatively little metal, about 0.25 to 0.50  mm depth. However, there are some roughing applications in which grinding removes high volumes of metal quite rapidly. Thus, grinding is a diverse field.

An adatom is an atom that lies on a crystal surface, and can be thought of as the opposite of a surface vacancy. This term is used in surface chemistry and epitaxy, when describing single atoms lying on surfaces and surface roughness. The word is a portmanteau of "adsorbed atom". A single atom, a cluster of atoms, or a molecule or cluster of molecules may all be referred to by the general term "adparticle". This is often a thermodynamically unfavorable state. However, cases such as graphene may provide counter-examples.

Albert Strickler (25 July 1887 – 1 February 1963) was a Swiss mechanical engineer recognized for contributions to our understanding of hydraulic roughness in open channel and pipe flow. Strickler proposed that hydraulic roughness could be characterized as a function of measurable surface roughness and described the concept of relative roughness, the ratio of hydraulic radius to surface roughness. He applied these concepts to the development of a dimensionally homogeneous form of the Manning formula.

Surface metrology is the measurement and characterization of surface topography, and is a branch of metrology. Surface primary form, surface fractality, and surface finish (including surface roughness) are the parameters most commonly associated with the field. Surface metrology is a fundamental measurement science critical across diverse manufacturing and engineering disciplines. While historically associated with precision machining and mechanical assemblies, it now plays essential roles in industries ranging from medical devices and electronics to aerospace and energy systems. Applications include ensuring biocompatibility of implants, optimizing semiconductor wafer quality, controlling paint adhesion in automotive manufacturing, enhancing solar panel efficiency, and managing thermal performance in electronic components. The field encompasses measurements from nanometer-scale surface features to large industrial components, making it indispensable for quality control, performance optimization, and failure prevention across modern manufacturing.

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, digital holography, confocal microscopy, focus variation, structured light, electrical capacitance, electron microscopy, photogrammetry and non-contact profilometers.