Abbott-Firestone curve

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The Abbott-Firestone curve.

The Abbott-Firestone curve or bearing area curve (BAC) describes the surface texture of an object. The curve could 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.[1]

Mathematically it is the cumulative probability density function of the surface profile's height and can be calculated by integrating the profile trace.[2]

The Abbott-Firestone was first described by EJ Abbott and FA Firestone in 1933.[3] It is useful for understanding the properties of sealing and bearing surfaces. It is commonly used in the engineering and manufacturing of piston cylinder bores of internal combustion engines.[4] The shape of the curve is distilled into several of the surface roughness parameters, especially the Rk family of parameters.


  1. ^ Johnson, K. L. (1985). Contact Mechanics. Cambridge University Press. p. 407. ISBN 0-521-34796-3. 
  2. ^ Stachowiak, G. W.; Batchelor, A. W. (2001). Engineering tribology. Boston: Butterworth-Heinemann. p. 450. ISBN 0-7506-7304-4. 
  3. ^ Abbott, E.J.; F.A. Firestone (1933). "Specifying surface quality: a method based on accurate measurement and comparison". Mechanical Engineering. 55: 569–572. 
  4. ^ Flitney, Robert. Seals and Sealing Handbook, Fifth Edition. Elsevier Science. p. 484. ISBN 1-85617-461-1.