Quality Control of the Electro-discharge Texturing

Automobile manufacturers specify in their requirements the characteristics of the microgeometry of metal plate quality. These quality criteria are a necessary condition for realization of supply of metal plates to the manufacturers. Each manufacturer has its own specifications. For example the Ford company requires that the roughness average on both sides of the metal plate be within the range 1,1 to 1,7 m, while the peak count has to be more than 50 cm 1 . These requirements are important mainly for good pressability and varnishability of the metal plates and also to achieve their long lifetime in the automobile industry. The roughness of the surface is a part of geometric unevenness of the surface with relatively small distances of uneven parts. For the purpose of evaluation of the surface relief statistical parameters were chosen which we call microgeometric quantities. The microgeometry of the surface is given by the roughness average and the peak count. Ra (roughness average) is a generally known and most widely used international roughness parameter. It is the mean arithmetic deviation of the roughness profile from the median line in the range of basic length 2 . Geometrically, this parameter is interpreted by the height of the rectangle constructed on the median line with the same area as the profile unevenness, enclosed by the profile from the median line. The values obtained show considerable accuracy in repeated measurement. Pc (peak count) is the number of peaks that intersect the defined upper and then lower level of the section, measured in the range of the evaluated length, transformed to the length of 1 cm 2 . In addition to the above quantities the following characteristics are used: – Rq – average quadratic deviation of the profile in the range of basic length, so called medium effective value – Rv – depth of the largest dip of the roughness profile within a single measured path – Rp – height of the tallest peak of the roughness profile within a single measured path – Rz – sum of Rv and Rp is the total depth of the roughness profile of a single measured path – Rmax – largest height of the profile (tallest peak to largest dip) measured in the range of entire length being evaluated