The drawing is still the contract
Even with a full CAD model, the engineering drawing defines what is inspected: which dimensions carry tolerances, which datums are used, which notes apply. First-article and in-process inspection therefore start by ballooning the drawing — numbering every requirement — and that work has traditionally been manual.
A PDF exported from CAD contains vector text and geometry. That makes dimensions, tolerances and feature control frames machine-readable, provided the software reads the geometry (the frames, the leader lines, the symbols) and not only the text layer.
Reading dimensions and GD&T frames
Ai-Inspect's Drawing Inspector detects dimension callouts, size tolerances, feature control frames and datum flags from the PDF vectors. Symbols that some CAD exports draw as line strokes (±, Ø, °) are recovered from their stroke signatures; rotated views, stacked frames and quantity prefixes (4X, 6X) are handled. Each detected requirement is assigned a balloon number and written to an inspection list that the operator can edit — anything the detector did not recognize is left for manual entry, never guessed.
From requirement to CAD feature
A balloon is useful only when it is linked to geometry. The inspection plan maps each requirement to a CAD feature by its view, its anchor position on the drawing and its nominal value — a Ø8 H7 callout in the top view is matched to a cylinder of diameter 8 in the corresponding orientation. Ambiguous matches (two holes of the same size in the same view) are flagged rather than resolved by chance.
Gated automatic measurement
Once the plan exists, the measurement runs in two tiers. High-confidence requirements — unambiguous feature link, full scan coverage, verified datum frame — are measured automatically. Everything else goes to a guided panel where the operator sees the drawing crop, the proposed feature and the reason for the hold, and completes the step with one pick. The result is one ballooned report with the same structure whether a row was automatic or guided.
- Automatic: linear sizes, diameters, positions and profiles with verified inputs
- Guided: ambiguous feature links, partial coverage, notes and manual checks
- Manual rows: threads, surface finish and anything requiring another instrument
Deliverables
The output of the drawing-driven workflow is an inspection package: the ballooned PDF, the inspection plan, the measured report (PDF, Excel, CSV) and, for shops running PAS CMM software, a process file that opens directly in PAS. Because the plan is saved with the program, the second part of the batch runs without touching the drawing again.