Wireform RFQ checklist: 14 things to send

Why a checklist beats a good drawing

A drawing describes a part. An RFQ describes a job. The difference is the wire, the volume, the finish, the inspection and the delivery terms, and none of those live comfortably in a title block. Suppliers fill the gaps with assumptions, and the assumptions are not the same from one supplier to the next.

The result is a set of quotes that cannot be compared. One supplier prices a standard temper because the drawing did not say, another prices spring temper and adds a stress relief. One assumes 5,000 pieces a year, another assumes 50,000. Both numbers are defensible, and neither answers the question you asked.

The checklist below is deliberately short. Fourteen items are enough to price a formed wire part and few enough that a buyer will actually complete them. Each item maps to a line in the quote.

Geometry: items 1 to 3

Send the drawing at the revision you want priced, with the title block, the general tolerance and every note visible. A PDF exported from a CAD system sometimes drops layers or notes, so check the file before it goes out. If the part is still moving, say which revision is current and when the next one is expected.

Add a 3D model where one exists. A formed wire part with bends in several planes is easier to quote from a model than from three orthographic views, because the supplier can check tool reach and bend order before pricing. A STEP file is usually enough. Do not send a model that disagrees with the drawing; the supplier will price the one that is easier to make.

Name the datum scheme and the characteristics that control assembly. This is the item that separates a useful RFQ from a drawing drop. A supplier who knows that the bend centres locate the part and the leg angle is cosmetic will quote the right inspection and the right tolerance, instead of guarding every dimension.

Wire and material: items 4 and 5

Item 4 is the wire diameter with its tolerance class. A nominal 2.0 mm means little on its own, because the permitted range sets the spring rate, the fit and the bend behaviour. ISO 22034-2 and the spring wire standards define tolerance classes, and the class belongs on the drawing next to the nominal size.

Item 5 is the material standard, grade and temper. Music wire to EN 10270-1, oil tempered wire to EN 10270-2, stainless 302 or 316, phosphor bronze, beryllium copper and copper alloys all behave differently. Temper changes the minimum bend radius, the springback and the load. A drawing that says only 316 stainless has left the supplier to decide whether the part is a spring or a trim piece.

If the wire is bought to a company specification, send the specification. If the part must be made from a named mill or a named heat, say so, because it changes the material route and the price.

Finish: item 6

The finish call needs four parts: the type, the standard, the thickness range and any area that must be masked. Add the post plating bake where the wire is high strength spring steel. Hydrogen embrittlement is a real risk on plated spring wire, and a bake that is assumed rather than specified is a bake that may not happen.

Say whether the drawing dimensions apply before or after finish. Plating adds a few micrometres and powder coating adds much more, and a tight wire diameter tolerance can be consumed by the coating. If the part is coated after forming, the coating also bridges bends and can change the fit in a housing.

If no finish is needed, say so explicitly. An empty finish field invites a supplier to add a protective oil or a passivation step that you did not ask for, and the price will include it.

Volume: items 7 and 8

Item 7 is the annual volume. It decides the process route, the tooling amortisation and the wire purchase. Give a number and a range, and say whether it is a forecast or a commitment. A supplier can work with either, but not with a blank.

Item 8 is the release size and the call-off pattern. A 20,000 piece annual volume released as one order is a different job from the same volume released as 500 per month. The second needs inventory, more setups and a more careful wire plan. The piece price should reflect that, and it will only reflect it if the RFQ says so.

Add the expected first delivery date and the programme life. A part that runs for three years can carry tooling amortisation that a one year bridge order cannot. If the programme is not confirmed, say that too, because it changes the risk the supplier prices.

Quality, delivery and the other six items

Item 9 is tooling ownership and transfer. Say whether you expect to own the program and the part specific tools, and whether they must transfer if the part moves. Item 10 is the inspection level and the first article requirement, including which characteristics must be reported and whether a functional load test is needed.

Item 11 covers any standard or declaration the part must meet, such as a material certificate, a RoHS declaration or a REACH statement. Item 12 is the delivery destination and the Incoterm, because a price ex works and a price delivered are not the same offer.

Item 13 is packaging and labelling. A formed wire part can tangle in a carton, and a clip with a delicate hook can be distorted by bulk packing. Say whether the parts need a tray, a bag, a nest or a defined orientation. Item 14 is the target date for samples and for production, which tells the supplier how much of the programme is still open.

The 14 items

The table is the checklist in full. It can be pasted into the RFQ document or attached as a covering sheet. The right hand column says why the item changes the quote, which is the argument for including it when a colleague wants to send the drawing and nothing else.

What a missing item costs

Take a clip with no temper on the drawing and no release size in the RFQ. Supplier A prices annealed wire, a single production run and a simple carton. Supplier B prices spring temper, monthly releases and a tray. Supplier B looks 40 per cent more expensive, and the comparison is meaningless because the two offers are for different jobs.

The usual response is a second round of questions. That costs a week, and it often produces a revised price that is closer to Supplier B. The checklist does not remove the need for a conversation, but it moves the conversation before the quote instead of after it.

Send the fourteen items in one folder with a clear file name, and put the open questions in the covering email. A supplier who can see which items are fixed and which are still open will price the fixed scope and offer the open items as options. That is a more useful answer than a single number built on a guess.

• Name the files with the part number and the revision
• Put the volume, the destination and the target date in the email body as well as the attachment
• Mark each open item as fixed, flexible or to be advised
• Ask the supplier to state any assumption they had to make