Hard Gauge Visualization – Effective Tool for MMR Verification Discussion

Abstract

The concept of author’s application Geometrical tolerancing that supports teaching and vocational training on the geometrical product specifications rules and verification methods is briefly presented. The maximum material requirement (MMR) modifier defined in the ISO 2692 changes the classical meaning of the geometrical tolerance symbols. The classical concept of a tolerance zone is replaced by the concept of a gauge. The idea of the maximum material modifier is based on functional requirement – assembleability. The paper contains a few screenshots from the interactive animations that are employed to demonstrate the MMR concept as well as relevant verification method. The sequence of developed scenes effectively help to understand and distinguish the role of the MMR modifier for the tolerance features and the datum features. For the datum features application of the MMR modifier produces an additional mobility for a group of all features considered as a pattern. This extra mobility depends on the datum feature actual mating sizes as well as on the 3D configuration of the datums and their precedence. It is demonstrated that employed animations clearly show that the bonus tolerance when the datum feature deviates from the MMC is virtually allowable rarely – only for specific configurations of a datum features geometry.