Improvements Needed to Elevate the State of the Art to Meet Evolving Industry Quality Standards

Due to the wide range of application of Geometric Dimensioning and Tolerancing (GD & T) Standards, the present industry standard method of calculating Gauge Repeatability and Reproducibility (GR & R) error on gauges and fixtures providing variable data exhibiting two or three dimensional variation is no longer valid. The current R & R process, when applied to circular and/or spherical zones, creates a positional tolerancing error of up to 73% of the allowable upper to lower tolerance limits. This paper presents an analysis of current methods and demonstrates through example an improved approach that takes into account variation in three dimensions, departing from single axis positional tolerancing and moving to two axis representation and, for positional tolerances, circular and/or spherical zones.