Assembly RFQ checklist: BOM, drawings, test and packing

An assembly RFQ is a BOM plus a process

A part RFQ asks a supplier to make something. An assembly RFQ asks a supplier to buy, receive, inspect, build, test, pack and ship a set of things. The price is mostly labour, test time and logistics, and the material can be a pass through or a risk the supplier carries.

That difference changes what the enquiry needs. A drawing set alone will produce a price for the build step. It will not produce a price for incoming inspection, for the fixture, for the test station, for the rework loop or for the packing that keeps a painted cover from being scuffed on the way to the customer.

The RFQ should describe the whole route. A supplier that has to guess the route will price the guess, and the guess is usually either too optimistic or padded with contingency.

Most of the cost sits in minutes that no drawing shows: walking to a bin, checking a label, testing a unit, repacking a return. The RFQ is the only chance to put those minutes on the table before they are priced by default.

The BOM: structure and approved sources

Send the BOM as a structured file, not a PDF of a spreadsheet. Every line needs a part number, a description, a revision, a quantity per assembly, a unit of measure and a source: free issue, supplier bought, or customer nominated.

Say which lines have an approved source and which have an approved alternate. A supplier that substitutes a latch to save cost can change the feel of the lid and the result of the function test. A supplier that cannot substitute at all may be stuck with a long lead time on a single source component.

Deal with scrap and attrition explicitly. Every assembly line loses components to handling damage, dropped screws and test failures. State the allowance, or state that the supplier carries it, and make sure the piece price reflects the answer.

Long lead components decide the launch date more often than the build does. Ask the supplier to flag the lines with a lead time longer than the build cycle, and decide whether to hold stock, negotiate a buffer or redesign around the part. That conversation belongs in the RFQ, because it changes the price.

Drawings: the assembly view and the interfaces

The assembly drawing should show the build in its finished state, with the interfaces that matter: mounting points, connector positions, label areas, cable routing and the surfaces that must not be marked.

Mark the critical characteristics on the assembly drawing rather than leaving them to the component drawings. The gap between a cover and a housing, the flush condition of a nameplate and the position of a terminal block are assembly results, and the assembler owns them.

Add the torque table, the adhesive callout and the test specification as controlled documents with revision numbers. An assembly instruction that lives in an email is not a controlled document.

• Assembly drawing at the current revision, with the build state shown
• Component drawings that match the BOM revision
• Torque table and adhesive callouts as controlled documents
• Test specification with limits, sample sizes and method
• Label artwork and the barcode standard the customer scans

Test and acceptance

State what every unit must pass before it is packed, and what a sample must pass per batch. A continuity check, a hi pot test, a functional cycle and a visual standard are separate requirements and each has a cost.

Name the equipment expectation. If the test needs a fixture that the supplier must build, say so and ask for it as a separate line. If the buyer supplies the test box, say who maintains it and who calibrates it.

Agree the reaction to a failure. A unit that fails a function test may be reworked, retested or scrapped. The RFQ should say which, and who pays for the time. Without that, the first bad batch becomes a negotiation.

A test that the supplier cannot perform without new equipment is a capital decision, not a labour line. Compare buying the box yourself and shipping it against paying the supplier to buy one, and write down who calibrates it and who owns it if the programme moves.

Packing, kitting and shipping

Packing for an assembly is a design task. A painted housing needs a bag or a foam layer. A long busbar assembly needs a rigid support. A kit with small fasteners needs compartments that survive the journey.

Decide whether the shipment is a finished assembly or a kit for the customer to build. Kitting looks cheaper on paper and often is not, because the kit has to be counted, packed and verified, and a missing screw stops a line.

Give the carton quantity, the label format and the pallet pattern. If the customer scans a label at goods in, the barcode standard belongs in the RFQ, not in a complaint after the first shipment.

Returnable packaging is worth considering where the volume is steady and the distance is short. For an export programme the return leg usually costs more than the carton, so single trip packaging with a known specification is often the better answer.

Volume, schedule and change control

Give the annual volume, the call off pattern and the ramp. Assembly labour scales with volume in steps: a cell that builds 50 units a day needs a different layout from one that builds 500. A supplier quoting the high volume rate for a low volume launch will lose money, and will recover it somewhere.

State the change process. Who approves a component substitution, how much notice a drawing change needs, and who pays for components that become obsolete. Assemblies carry more exposure to change than single parts because a change on one line can strand stock on five.

Ask for price validity and the index, if any, that the price follows. Labour rates and freight move, and a price with no validity clause is a price that will be reopened.

A ramp that starts at a low volume and climbs quickly needs a layout that can absorb the climb. Ask how the supplier would add a second shift and what that does to the piece price, because the answer is often a step change rather than a smooth curve.

Share the forecast horizon you can actually commit to, and ask what the supplier needs to hold a rate. An assembler that can see three months of firm orders will plan labour differently from one working week to week, and the difference shows up in the price and in the overtime.

The checklist

The table below is the short version. Send the items in the order the supplier builds the price, and the quote will arrive with the labour and test time visible rather than buried in a total.

Where an item is missing, mark it as an open assumption instead of leaving the field blank, so the supplier prices the gap openly. A blank field is usually filled with the cheapest assumption, and the cheapest assumption is rarely the one that survives contact with production.