Tolerancing – miniseries
Second part | Definition of Geometric Dimensioning and Tolerancing in ISO GPS
Futurities Year 22 n°2
By Florian Weidenhiller | EnginSoft
This article explores the practical implementation of Geometric Dimensioning and Tolerancing (GD&T) according to the ISO GPS standards, focusing on the functional definition and consistent application of Datum Reference Frames (DRFs). DRFs, derived from a component’s functional geometry and assembly sequence, constrain six degrees of freedom to ensure stable alignment and reproducibility during production and assembly. The ISO GPS approach emphasizes a top-down consistency of DRFs across all product levels to prevent variation accumulation and quality issues. Tolerances—including position, profile, orientation, and form—are defined relative to DRFs based on product function, materials, manufacturing processes, and environmental factors.
Effective adoption of ISO GPS requires comprehensive training of designers, engineers, and quality personnel, supported by flexible courses such as computer-based training modules, as experienced in BOSCH. Integrating GD&T early in the design process enables systematic tolerance management, leading to optimized costs, enhanced product quality, and reliable manufacturing outcomes compliant with international standards.
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CASE STUDY
In a recent interview, Enrico Boesso (EnginSoft) and Daniel Campbell (Capvidia) discussed how Model-Based Definition (MBD) is transforming manufacturing by replacing traditional 2D drawings with data-rich 3D models as the "single source of truth".
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CASE STUDY
Dimensional management in modern manufacturing demands more than just accurate geometric tolerances—it requires data consistency, traceability, and automation across the entire product lifecycle. Traditional practices like annotated PDFs and Excel-based inspection plans introduce risk and inefficiency by detaching product and manufacturing information (PMI) from the 3D model. Siemens’ NX Inspector addresses this challenge through the introduction of Model-Based Characteristics (MBC)—standards-compliant, machine-readable data objects that convert each PMI requirement into a uniquely identified, traceable element within the CAD environment.
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