Function-Oriented Dimensional Metrology – More than Determining Size and Shape

Today’s dimensional metrology has undergone some generational changes. Looking back in history, manufacturing functional products without metrology was just a trial and error procedure, so only a small number of simple products were produced. First, with the implementation of simple gage blocks the construction of complex buildings such as the pyramids were possible. Later, during the industrial revolution requirements for mass production increased, so simple 2-point measurements were no longer sufficient to ensure mating ability and interchangeability of more and more intricate compo-nents. Systems for geometrical dimensioning and tolerancing (GD&T) have been introduced, which enable the geometrical description of complex product properties, and also measurement instruments were developed further from simple manual measurement instruments to high-resolution multi-sensor coordinate measuring machines, which combine tactile, optical and x-ray-tomographic measurement principles. Currently, another paradigm shift is imminent: Conformance proving is changing from pure-ly geometry oriented measurements to function oriented virtually testing. By modeling and simulating the function of a component it is possible to evaluate the functional ability of a component based on dimensional measurement data. This leads to an unambiguous product specification, a better process understanding, a verification result based directly on function-oriented parameters instead of indirectly function related dimensional parameters and so to a more veridic prediction of functional ability. Key words: dimensional metrology, function-oriented parameters, GD&