Decide how far the supplier should take the product
Sheet metal work with assembly can mean three different things, and the quote differs for each. The first is a kit of finished parts, where the supplier makes and finishes every part and you assemble them. The second is a sub-assembly, where hardware, brackets or welded sections are joined before shipping. The third is a finished unit, where purchased components such as hinges, latches, gaskets, labels and sometimes wiring are fitted and the unit is tested. Say which one you want in the first line of the RFQ, because a supplier that prices a kit and a supplier that prices a finished unit are not quoting the same job.
Give the supplier an assembly drawing and a bill of materials
A STEP file of the assembled product and a bill of materials are what turn a stack of parts into a quotable assembly. The bill of materials should list every fabricated part and every purchased item with a quantity and a part number, and should say who supplies each item. Without it, the supplier has to guess whether gaskets, screws, nameplates and cable glands are included, and the quote will either leave them out or include them at a margin you did not expect. An assembly drawing that shows the fastener type, the torque where it matters and the order of assembly removes most of the later questions.
Settle who buys the purchased components
Hinges, locks, latches, handles, gaskets, DIN rail and standard fasteners are usually bought, not made, and their lead time can be longer than the sheet metal itself. Decide whether the fabricator sources them, whether you supply them free of charge to the supplier, or whether a mix of both applies. Consigned parts need an agreed quantity with a spare allowance, a delivery date and a rule for who pays when parts are damaged during assembly. If the supplier sources them, ask for the brand or an approved equivalent, since a substitute lock or gasket changes both the fit and the feel of the product.
Plan the order of finishing and assembly
Parts that will be powder coated or anodized generally cannot have rubber gaskets, plastic parts or tapped threads fitted before the finish, and some hardware has to be masked or installed afterwards. A grounding stud needs a bare metal contact surface, and a coating applied over a threaded insert can make the thread tight or unusable. Ask the supplier to describe the sequence: cutting and forming, welding, hardware insertion, finishing, then final assembly. If the finish has to be applied after assembly, say so, because it changes what has to be masked.
Check fit where parts meet, not only part by part
A door that closes on every individual drawing can still bind when four tolerances add up, so assemblies should be quoted with a fit check in mind. Name the interfaces that matter, such as the door gap, the panel-to-frame alignment and the position of mounting holes against a customer-supplied part, and agree how they are checked. For a first order, a single assembled sample that is checked against the real mating parts catches stack-up problems before the batch is built.
Include packing, labeling and the final check in the scope
An assembled unit is larger and more fragile than a pile of parts, so packing needs its own line: protective film on visible surfaces, corner protection, foam or cartons sized for the finished unit, and a count of how many units fit in an export carton. Labels, nameplates and serial numbers should be defined at the same time, including where they sit and what they say. State the final check that must happen before shipping, whether a dimensional check, a functional test of doors and latches, or a visual inspection against a signed sample.
| Input | Why it matters |
|---|---|
| Assembly level | Say whether you want a kit of parts, a sub-assembly or a finished unit; the quote scope and price differ for each. |
| Assembly drawing and BOM | List every fabricated and purchased item with quantity, part number and who supplies it. |
| Purchased components | Name who sources hinges, latches, gaskets and fasteners, with brand or approved equivalent and lead time. |
| Finish and assembly sequence | State what is fitted before or after coating and which areas must be masked or left bare. |
| Critical fits | Name the interfaces that must fit, such as door gaps and mounting positions, and how they are checked. |
| Packing and labeling | Define protective film, carton size, units per carton, labels and serial numbers for the finished unit. |
| Final check | Agree the dimensional, functional or visual check that must pass before shipping. |
Next step
Use the guide to prepare a cleaner inquiry, then attach the best available files through the RFQ form. If an item is unknown, say so directly so the first reply can separate quote assumptions from confirmed requirements.