Multi-Variant Large Parts: Scan, Overlay CAD, 360 s per Part
Construction machinery, agricultural machinery, rail transit and commercial vehicles all draw large or complex parts from several suppliers, and specifications and conditions vary widely. Missing parts, wrong assembly, and anomalies in brackets, holes or accessories can all enter production at goods-in. The traditional response is a person with drawings checking item by item, which is slow, produces inconsistent records, and makes wrong drawings or wrong items more likely as variants multiply.
With scattered suppliers, CAD is the only common baseline
There is no single physical reference sample to compare against, so the design model becomes the shared decision basis. That is why the first task is not buying a device but cleaning up the CAD models for each part. For a part whose model is missing or whose revisions are confused, an overlay comparison has nothing to stand on.
Outbound self-check and inbound recheck need one baseline
Consistency is checked at two points: the supplier self-checks before shipment, and the OEM rechecks on arrival. Sharing one inspection baseline is what makes the accepted state at dispatch agree with the accepted state at receipt, and it aligns both sides on what the result means, which speeds up dispute handling.
The scan is what binds a workflow to a part
When a delivery arrives, the workpiece code is scanned and the matching inspection workflow is retrieved. The workflow library is maintained by part code; each part carries its own CAD model and inspection items, and the item order is fixed in the workflow, from top to bottom and from main structure to accessories, which reduces backtracking. Inspection records bind automatically to the part ID, so batches of the same part can be compared without manual transcription.
One registration, then a division of labour
The system sets the model upright and orders the check items: the tablet recognises physical features, aligns the CAD to the part and holds the overlay while the inspector moves. Large parts provide enough contour and feature surfaces for a single registration to hold. The inspector makes the visual calls: a missing part is CAD present and part absent; a wrong part is a displacement between part and CAD; bracket, hole or accessory anomalies show as deviation in the corresponding region.
Changeover touches data, not hardware
The multi-variant approach is a workflow library organized by part code. Changeover needs no hardware reconfiguration, only maintenance of models and workflow data. Site lighting and placement differences are normalized by registration: the part does not need a fixed orientation, and adjusting the tablet angle and distance is enough to compare under normal shop conditions.
The preconditions behind 360 seconds
A single part takes about 360 seconds, covering scanning, registration, item-by-item comparison and record output, subject to site acceptance results. Selection should weigh the number of part types, CAD completeness, and site lighting and placement. For stable batches of simple parts, items can be trimmed; for high-risk accessories, comparison frequency can be increased; where fine tolerance judgment is required, metrology should be added.
What to settle before deployment
Why check twice, at dispatch and at receipt?
The supplier check stops problems at their source; the inbound check stops shortages and errors from transport or batch variation. Sharing one baseline is what closes the loop.
How are records tied to the part?
The part code is scanned first, the workflow is retrieved, and results bind automatically to the part ID, so all inspection history can be traced by part.
What if CAD coverage is incomplete?
Govern the models first. For parts with missing or confused revisions, overlay comparison is meaningless, and no software step bypasses that.
Can it replace dimensional measurement?
No. It performs structural consistency checks at a qualitative level, not precision dimensional measurement; fine tolerance judgment needs separate metrology.