Welded Frame Check: AR Zones Catch Missing Subparts
Before a large welded structure is assembled, its integrity has to be confirmed: whether every subpart was welded in, whether positions are correct, and whether holes and cutouts match the design. The workpiece is large and structurally busy, so the traditional method is an experienced inspector walking around it with drawings. That is slow, and the skill does not replicate. If an integrity problem survives until final assembly, repair means re-lifting, cutting and re-welding, far more expensive than a screen at goods-in.
One CAD baseline ends the tolerance argument
The hard part of a structural check is not seeing; it is agreeing on how much deviation counts as a fault. The cell makes CAD the single baseline, so supplier and OEM compare against the same 3D model and a dispute has an objective reference instead of two parties trading experience. Once the criterion is common, the on-site conclusion carries weight and the record can feed later metrology.
Presence is decided zone by zone
CAD defines the region each subpart occupies. Under overlay, software tests whether the live image inside that region matches the CAD projection. If a bracket should be there and is not, the region fails and the subpart is reported missing. The test does not depend on the inspector's viewing order or on which side they happened to inspect first.
A hole is judged by edge offset, not by resemblance
Edge comparison runs in two steps. The CAD is projected into the current view to generate theoretical edges, then actual edges are extracted from the corresponding image region. The two are compared point by point in the same image coordinate system and the deviation is visualized, with out-of-tolerance locations highlighted. Hole and cutout contour problems move from subjective judgment to a measured edge offset.
Face-by-face coverage, then a single roll-up
A single view covers only part of a large fabrication. The inspector walks around the workpiece in a defined sequence while tracking keeps the model aligned to the physical item. Multi-direction viewing is organized by face rather than by wandering: each face completes its own automatic zone check and edge comparison, and the roll-up happens only after all faces are done. That aggregation step is the safeguard against a partial verdict on a large part.
Move the miss risk from memory into the process
The core risk is an escape. On a very large workpiece, a person walking around it will eventually miss a rear-facing, high or occluded area. The technical answer is to turn looking into a structured process: CAD defines zones, software checks each zone, and the human role returns to confirmation and disposition. Standardized records are the quiet benefit. Screening records are stored by workpiece and checkpoint, batches become comparable, problem parts can be traced, and supplier quality has a data foundation.
Five hundred eighty seconds and the metrology boundary
The screening cycle is about 580 seconds per part, subject to site acceptance results. The method is qualitative screening with deviation visualization; exact dimensional values still come from precision metrology. The relationship is upstream and downstream, not substitution. The fit is a very large welded structure or complex assembly with many features that must be checked in place.
Points that get pressed on site
What does markerless recognition register against?
Structure in the CAD and in the real part. The system extracts structural edges, holes and similar features from the tablet image, solves the current view and pose against the CAD projection, and never applies markers to the workpiece.
Must the inspector walk all the way around?
Yes. One view covers only part of the part, and the whole-part conclusion is assembled from every face. Skip one face and the conclusion is incomplete.
Can the edge comparison be used as a dimension?
It produces a deviation indication and a visual, not a metrology value. Exact numbers remain with precision metrology.
How long are the records kept?
Anomalies are recorded by checkpoint and stored with the whole-part result, serving as incoming inspection evidence and as input for later metrology review.