Comparing 14 m Crane Assemblies Without a Metrology Room
A crane assembly can reach 14 metres and is an oversized part by any definition. Crane building is single-piece and low-volume, so components are large and long, and craning them is itself a high-risk, slow operation: long routes inside the shop, impact risk in transit. Conventionally the part goes to a metrology room, where transport, handling and queueing add up. Metrology capacity is short for parts this size, and waiting for a slot becomes normal.
Waiting for a slot costs more than the inspection
When inspection capacity is short, production runs to the rhythm of the inspection resource. Every check occupies crane capacity, and the more checks there are, the more transport cost and risk accumulate. The site requirement is therefore direct: compare the part against CAD without moving it, and take the handling step out of the process altogether.
Fourteen metres means segments
One field of view covers only a local area, so the job is segmented scanning and zoned comparison. The difficulty is the seam. Adjacent zones keep an overlapping reference at the joint so the comparison relationship does not drift after stitching, and the whole CAD model is used as the basis for verifying coverage. Segmentation is not arbitrary: split points belong where structural features are clear and easy to align, otherwise every new zone starts with a fresh struggle.
Paint, rust and light: three site disturbances
A production floor is not a metrology room. Paint and rust on the surface disturb feature matching, and a simple clean of the key areas before capture restores registration stability. Where lighting is poor, supplementary light fixes it, though the software works at normal shop illuminance. These actions sound trivial but decide whether registration holds, and they are the substance of on-site deployment planning.
Software on a terminal is the second benefit
The scheme runs as software on a mobile terminal, with a CAD model library underneath, so an inspector calls up the matching model at any station and compares there. The terminal travels with the person, inspection points are not tied to a fixed station, and every station shares one judgment basis and one version. That is also why the scheme deploys across several production sites: one software and one criterion to replicate.
What 900 seconds covers
The cycle is about 900 seconds and covers everything from registration to completed comparison, with the part never moved and the inspector walking around it, subject to site acceptance results. The model library is maintained by assembly type, so preparing a new component is mainly a model import and a check-item configuration, with no fixed brackets to install.
When metrology still gets the part
On-site AR comparison completes the visual consistency check against CAD and releases the part, replacing the transport-based route. Where a tolerance is strict, metrology still confirms it afterwards. Selection should weigh the part length against the walk path, the site lighting, and how much the plant depends on its metrology room; where the part is dozens of times longer than one field of view, the walk path and segmentation strategy need more care.
What the plant asks first
How is a 14 m assembly fully covered?
Segmented scanning and zoned comparison, with an overlapping reference between neighbours and the overall CAD model constraining coverage as the inspector walks the part.
Why emphasise replication across sites?
The inspection runs as software on a terminal and does not depend on fixed metrology hardware, so deployment is software plus a CAD library, and the criterion can be unified with the software.
Do site conditions change the result?
They do. Lighting and occlusion call for an adjusted shooting angle, paint and rust need cleaning before capture, and the terminal can move freely around the part.
How are records traced?
Records are archived with the part number and trace back to the station and the inspector.