Development of a traceability route for areal surface texture measurements

Modern manufacturing industry is beginning to benefit from the ability to control the three dimensional, or areal, structure of a surface. To underpin areal surface manufacturing, a traceable measurement infrastructure is necessary. In this thesis a practical realisation of areal surface traceability is presented, which includes the development of: a primary in-strument, methodologies for using the primary instrument to calibrate material measure-ment standards used as standard transfer artefacts, and the process of transferring this traceability to industrial users of stylus and optical instruments.

The design of the primary instrument and its complex measurement uncertainty model are described, including detailed analysis of the input parameters of the uncertainty model and their effect on the co-ordinate measurements of the instrument.

The development of the process of transferring the areal traceability to industrial users lead to a set of metrological characteristics applicable to all areal surface topography measuring instruments. The set of metrological characteristics, now included into international stand-ards, comprise of: measurement noise, flatness deviation, amplification, linearity and squareness, and resolution. Despite the differences in operation of the various types of in-strument, the idea behind this set of metrological characteristics is based on the fact that these instruments produce three dimensional data sets of points, which is a new approach in the field. Metrological characteristics are quantities that can be measured directly, gener-ally using calibrated material measures. The development of standard methodologies for calibrating the metrological characteristics, and the explicit relationship between the metro-logical characteristics and the measurement uncertainty associated with the co-ordinate measurements provided by the instrument is presented. Many of the techniques described in this thesis are now being discussed for inclusion into international standards.