“The MOTIF-method (ISO 12085) — a suitable description for functional, manufactural and metrological requirements”

Abstract

The real geometry of a workpiece has including their micro- and macro-geometrical deviations an effect on the one hand to the functional behaviour and on the other hand to the real geometry marks of the whole manufacturing process. The metrology has, because of the mutual relations between function and manufacturing, the important task to purify the connections between the real geometry and the function. Parameters and functions have to be defined and standardized for the complete description of the surface roughness and waviness to be suitable for the functional, productional and meteorological requirements. Surface roughness and waviness measurements in industry are internationally widespread performed by stylus instruments. To separate roughness from waviness, the mean line system uses electronic filtering. The MOTIF-method (ISO 12085) offers an alternative evaluation to separate roughness and waviness by means of unfiltered profiles. The MOTIF-method is a graphical evaluation with the complete description of roughness and waviness with merely 7 parameters and the evaluation based on the upper envelope line. The MOTIF-method is a system for the evaluation of the primary profile and based on the envelope system and is suitable as an alternative to the mean line system. The MOTIF-method determines the upper points of the surface profile, which have an importance for the functional behaviour. Roughness and waviness can be evaluate directly based on the diagram of the unfiltered profile. Specially the evaluation of short profiles is advantageous, as the MOTIF-method requires no pre- and post-travel. The parameter of the MOTIF-method reflects the geometrical dimension of the profile irregularities. The typical surface profile is possible to be reconstructed with the additional informations of the variances. The separation of roughness from waviness happens absolute sharp with an automatically adjustment to the width of the characteristic irregularities of the profile. The MOTIF-method finds out within these limits the horizontal and vertical properties of the essential profile irregularities without elimination of important profile points. It is very well suited for technical inquiries on unknown surfaces and processes, functions related to the envelope of the surfaces and profiles with very close wavelengths for roughness and waviness.