Geometric Dimensioning and Tolerancing (GD&T) links design, production and metrology, but inconsistent interpretation can produce conflicting measurements, scrap and repeated exchanges between teams. Metrologic DCS says those risks are growing as product manufacturing information (PMI) is embedded in CAD files and standards evolve. The supplier has set out four practices for making inspection preparation and reporting more reliable, from reading design intent to issuing shop-floor reports.
Use PMI as the starting point
The first step is to decode the design intent carried by PMI: the targeted feature, references and tolerance. Metrologic DCS says manual handling is error-prone because a copied value or misunderstood reference can lead to inspection against the wrong requirement. It recommends software that starts from PMI and creates features and evaluations from the part’s digital definition rather than requiring tolerances to be re-entered. The company says this reduces re-keying and interpretation gaps and saves time at the start of program preparation.
Automate datum reference frames
A datum reference frame (DRF) establishes where measurement begins. It comprises reference features such as A, B and C and determines which degrees of freedom are constrained. Metrologic DCS warns that an incorrect build order or poorly selected degrees of freedom can lead one operator to accept a part that another rejects. It recommends automating the step so the DRF and constrained degrees of freedom follow the drawing definition. Metrologic says Metrolog creates the DRF automatically when a GD&T is evaluated.
Reuse references from the CAD model
Reference labels already exist in the CAD model from the design office. Recreating them during program preparation wastes time, can introduce discrepancies and forces rework when definitions change, according to Metrologic DCS. Parts with many annotations also make it hard to track which items have been handled and which still need measurement. It recommends starting from PMI-derived DRFs, predefining GD&T and keeping a clear view of each annotation’s location and measurement status. Its Scan GDT function reads decoded PMI and assigns a status so users can validate decoding and measurement.
Tailor reports to the reader
Metrologic DCS argues that a “pass” or “fail” report does not tell a machine operator what to correct, leaving trial-and-error adjustment, scrap and correction loops. It proposes a numerical table for quality control, a go/no-go report for quick decisions and a decomposition analysis for the operator. Metrolog separates an evaluated feature’s defect into form, size, position and orientation alongside the global defect, which the company says helps identify the dominant problem first. Metrologic DCS claims a well-designed report reduces scrap and speeds corrective action.