Metrologic DCS has set out four practices aimed at reducing interpretation gaps in Geometric Dimensioning and Tolerancing (GD&T), the language linking design, production and metrology. The company says poor interpretation can lead to conflicting measurements, scrap and costly exchanges between teams as Product Manufacturing Information (PMI) becomes more common in CAD files and standards continue to evolve.
Start with PMI, not re-keyed tolerances
The first recommendation is to begin with PMI and decode the design intent: the target feature, the references and the tolerance. Metrologic DCS says manual handling is prone to error, including copied values and misunderstood references. It recommends software that uses PMI as its starting point rather than requiring users to re-enter tolerances, so features and evaluations are created from the part’s digital definition. The claimed result is less re-keying, fewer interpretation gaps and time saved during program preparation.
Automate the datum reference frame
The second practice concerns the Datum Reference Frame (DRF), which defines the measurement origin through reference features A, B and C, and determines which degrees of freedom are constrained. Metrologic DCS warns that an incorrect build order or poor selection of degrees of freedom can make the same part appear conforming or non-conforming depending on the operator. It recommends automating the step so the DRF and degrees of freedom follow the drawing definition, making results repeatable across operators, machines and sites. In its Metrolog software, the company says the DRF is created automatically when a GD&T is evaluated.
Reuse CAD references and tailor reports
The third tip is to reuse imported DRFs instead of recreating references already defined in the CAD model. Metrologic DCS says rebuilding them wastes time, invites discrepancies and creates rework when definitions change, while parts with many annotations make it difficult to track which requirements have been handled. Its Scan GDT function is said to read decoded PMI and assign a status so users can validate decoding and measurement.
Finally, the company argues that pass/fail reporting does not tell the shop floor what to correct. It recommends numerical tables for quality control, Go/No-Go reports for quick decisions and decomposition analysis for operators. Metrologic says its software separates an evaluated feature’s defect into form, size, position and orientation, alongside the global defect, to show which type dominates and should be addressed first.