2. Different geometric surface deviations

A surface profile is the curve resulting from the intersection of the actual surface and a specified plane. This plane is perpendicular to the specimen surface and generally oriented perpendicular to the direction of the machining ridges. In addition to the nominal shape of the part, a surface profile is made up of different geometric deviations (figure 1 ), to which different profiles correspond (table 3 ):

• profile P, primary profile (order 1 + 2 + 3 + 4), on which structural parameters are defined, designated by a symbol beginning with the letter P, e.g. Pt, Pa, etc. ;

• W profile, ripple profile (order 2), on which ripple parameters are defined, designated...