Releasing Rail Parts at Goods-In in 660 s With Tablet AR
Large rail metal components arrive at the receiving area and only move on once inspection clears them. The old routine was tape measures and sample templates: many points on a big part, so a single confirmation took a long time, while the window for checking is short because parts are often transferred again the same day. Worse, once a wrong part reaches machining or assembly the correction cost climbs sharply and can upset the production schedule.
The gate belongs where correction cost jumps
Rail OEMs and suppliers used to pass quality information on paper inspection sheets, so the conclusion lagged behind the material. By the time a problem surfaced, the part was usually already on the line. Moving the quality confirmation forward into receiving means a clear verdict before the release decision, not a trace afterwards. It also means the inspector has to reach that verdict with the part still on the floor, in the condition and location it was delivered.
The CAD revision has to follow the order
Incoming models and batches are mixed, and if the CAD revision does not match the order the comparison baseline is wrong and every verdict derived from it is wrong too. So the first action at the start of a shift is not aiming the terminal at the part but pulling the CAD revision that belongs to this delivery. Revision checking should be a hard step in the process rather than a matter of diligence, because a model change is exactly when the wrong baseline gets picked up.
Registration in an open yard passes three tests
Receiving areas have changeable light, uneven ground and parts with very different surface textures. A misalignment between model and object turns directly into a dimensional misjudgment. The technical answer is to register on stable features that light affects least, edges and hole positions, and to keep tracking and correcting drift while the inspector moves. Where a deviation looks likely, the inspector is guided to close in and look again before it is recorded.
Four steps and what each leaves behind
The sequence is CAD import, markerless registration, overlay comparison and exception recording. The terminal camera captures features on the part, solves the spatial transform between model and object, and overlays CAD outlines and hole positions on the live image; out-of-tolerance points are marked automatically and recorded. The result is not a bare pass or fail: each part gets an incoming inspection file with the location and magnitude of the deviation, bound to its receiving batch. Quality confirmation shifts from experience and judgement to data on record.
No fixture, no crane, 660 seconds
The system is AR inspection software plus a mobile terminal, with no fixed station and no tooling. The inspector's route is planned in advance around the part's features to avoid wasted walking, and the comparison runs at about 660 seconds per part, subject to site acceptance results. The verdict is given on the spot rather than filled in later, and comparison records are summarised by receiving batch and fed back to the supplier.
The inspection strategy can be graded by supplier risk. For suppliers with stable incoming batches, the comparison list can be trimmed item by item; for a new supplier or a changed part, full feature verification stays. Precision below the millimetre level still belongs with metrology. AR comparison is here a fast release gate, not a replacement for measurement.
What a receiving bay team asks
Why not take the part to a dedicated measuring machine?
These parts are large and heavy; craning them costs money and risks secondary damage. Inspecting in the receiving area removes the move and matches the arrive-and-check rhythm of incoming material.
Does strong light or shadow break the registration?
It reduces feature legibility. The system prefers edges and holes, which are less light-sensitive; if needed the inspector moves to a shaded side or adds light, and in extreme cases a simple screen is set up on site.
What can it actually catch?
Anything inconsistent with the CAD revision: outline dimensions, contour shape, hole position, missing holes, displaced features. Pass or fail comes from the overlay result against the tolerance setting.