Two quotations for the same body shop can differ by a factor of three and both be honest. Almost all of that difference is the scope split — who supplies the robots, the welding equipment, the conveying, the fencing and the control. Until that is agreed in writing, a price for a welding line means nothing, and comparing two of them means less. This is how the split is normally drawn, what each row costs you, and where the money actually moves.
The three rows that decide the budget
Robots, welding equipment and conveying are the three heavy rows. A plant that already runs robots and welding sets, and that only needs new tooling for a new model, is buying a fraction of what a greenfield line costs — the fixtures, the hangers, the base plates and the station control, and nothing else.
Everything we have delivered in this field was bought that way: on three projects for car plants in Russia, the robots, positioners, welding sets, fume extraction and fencing stayed on the plant's side, and we supplied the tooling and the control interface. It is not a discount; it is a different scope.
What normally sits on the supplier side
Welding and assembly fixtures, shared base plates, hangers and marking; the steel structure that carries them; station control — valve island, clamp sequencing, two-hand start, safety circuit and the HMI; export packing, the container loading plan and the export documents.
These are the rows where the engineering lives, and they are the rows a plant cannot easily self-supply for a model it has never built.
What normally sits on the plant side
Utilities to the cell — power, compressed air, water and extraction to the connection points the supplier marks — and the civil works: floor loading, pits and anchor points to the supplier's foundation drawings.
Installation is shared in practice. The plant supplies cranes, riggers and electricians; the supplier supplies supervision, robot teaching and tuning. Writing it as "installation by supplier" without naming the cranes and the labour is how installation disputes start.
The rows that should move
Robots, welding equipment, positioners and robot bases, conveying between stations, fencing and light curtains: each of these can sit on either side, and each should sit wherever the project is cheaper for the buyer. A plant with a standing robot brand and a maintenance team trained on it usually keeps the robots. A plant building its first line usually does not.
Ask for both versions. A supplier who cannot quote the tooling-only scope separately does not have its own costing in order.
How to write it so it holds
One table, one row per item, three columns: item, supplied by, notes. Every row filled in — no blanks, because a blank is read by each side as the other side's problem.
Then two further columns that most contracts forget: who installs it, and who commissions it. On a retooling project we delivered, installation and commissioning were priced per item against the plant's own asset codes, which is what let the plant stage the changeover shop by shop instead of stopping the whole line at once.
Frequently asked questions
Is keeping our own robots really cheaper?
For a model change, almost always. The robots are not what stops you building a new body — the tooling is. Keeping them also keeps your maintenance team, spare parts and programming knowledge in place.
We have mixed brands in the shop. Is that a problem?
No. The station control, safety circuit and robot interface are designed around whichever controller sits in that station. It is a design input, not an obstacle.
Who pays for something nobody listed?
Whoever wrote the table last. That is the argument the table exists to prevent — fill in every row, including the obvious ones.
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