The Abbott-Firestone curve or bearing area curve (BAC) describes the surface texture of an object. The curve can be found from a profile trace by drawing lines parallel to the datum and measuring the fraction of the line which lies within the profile. Mathematically it is the cumulative probability density function of the surface profile's height and can be calculated by integrating the profile trace. The Abbott-Firestone curve was first described by

Ernest James Abbott Ernest is a given name derived from Germanic word ''ernst'', meaning "serious". Notable people and fictional characters with the name include: People *Archduke Ernest of Austria (1553–1595), son of Maximilian II, Holy Roman Emperor *Ernest, M ...

and Floyd Firestone in 1933. It is useful for understanding the properties of sealing and bearing surfaces. It is commonly used in the engineering and manufacturing of

piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tig ...

cylinder bores of

internal combustion engines An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

. The shape of the curve is distilled into several of the

surface roughness Surface roughness, often shortened to roughness, is a component of surface finish (surface texture). It is quantified by the deviations in the direction of the normal vector of a real surface from its ideal form. If these deviations are large, ...

parameters, especially the Rk family of parameters.

References

{{reflist Engineering mechanics Tribology