Two factories quote the same CNC machined part. One comes back at half the price of the other. Most buyers assume someone is padding the margin. Usually nobody is: the two shops priced two different parts, because the request they received left out different things.
A CNC machining RFQ checklist — an RFQ pack — is the set of files, specifications and commercial terms you send before a supplier prices anything. When it is incomplete, a Chinese machine shop has to guess — and a shop that guesses low to win the order will recover the difference later, in change orders, tooling charges or a part that does not assemble. This is the checklist we use before a custom metal parts enquiry goes out. It applies to CNC machining, sheet metal fabrication and stamping alike.
The 12-item RFQ pack checklist
Send these as one folder, with a single cover email that names the revision and the deadline for questions. Version numbers matter more than people expect: “bracket_v3.step” and “bracket_v3_drawing.pdf” should describe the same part.
| # | What to send | Why it changes the quote |
|---|---|---|
| 1 | 3D model (STEP or IGES), with revision in the filename | Drives tool paths, setup count and cycle time. A PDF alone cannot be priced reliably. |
| 2 | 2D drawing (PDF + DXF), dimensions and GD&T where needed | Defines what is inspected. Without it, the shop assumes the loosest interpretation. |
| 3 | Material grade and condition (e.g. 6061-T6, 304, SPCC) | Material cost, cutting behaviour and finishing options all depend on it. |
| 4 | General tolerance note, plus only the critical dimensions called out | A blanket tight tolerance on every dimension can multiply machining time. See our ISO 2768 tolerance guide. |
| 5 | Surface finish: as-machined, anodised, powder coated, plated, and colour | Finishing is often subcontracted; it adds cost, lead time and a second inspection. |
| 6 | Quantity tiers (e.g. 10 / 100 / 1,000) not one number | Setup amortisation and tooling decisions change completely between prototype and production. |
| 7 | Target unit price or budget range, if you have one | Lets the shop propose a different process instead of quietly dropping a requirement. |
| 8 | Inspection requirement: AQL level, FAI, CMM report, or sample approval | Inspection is real work and belongs in the price, not in an argument after production. |
| 9 | Certificates needed: material cert, mill test report, RoHS, ISO 9001 scope | Some documents require a specific mill or a registered scope; decide before the order. |
| 10 | Packaging, labelling and rust protection for dense metal parts | Heavy parts damage easily in transit; packaging is a line item, not an afterthought. |
| 11 | Incoterm and destination (EXW, FOB, DAP or DDP, and the port or address) | Without this, quotes are not comparable. See landed cost in 2026. |
| 12 | Deadline, sample requirement, and who approves the first article | Sets the production slot and prevents a “surprise” sample charge later. |
The three files that matter most
If a buyer sends only one thing, send the STEP file. It carries the geometry that CAM software needs to estimate cycle time. Pair it with a dimensioned 2D drawing, because a model alone does not say which dimensions are critical or what surface finish is expected. Keep a PDF in the folder as well: it is what people actually open on a phone in a workshop.
A common failure is a model and a drawing that disagree. The shop will follow whichever it noticed last. Before sending, open both and check the revision letter, the hole sizes and the overall envelope. Five minutes here prevents a container of parts that fit nothing.
Tolerances: be precise, not universally tight
A general tolerance note in the title block — ISO 2768-m, for example — is enough for most non-critical features. Mark tight tolerances only on the dimensions that mate with another part. Repeating a tight value on every dimension forces extra setups, slower feeds and 100% inspection, and it is the single most common reason a Chinese CNC quote arrives higher than expected. Our CNC quote cost breakdown shows where those hours appear in the price.
Ask for quantity tiers, not one price
A prototype price and a production price are built differently. At ten pieces you are paying for programming and setup. At a thousand, the conversation is about fixture design, tool life and whether a stamping die or a casting makes more sense. Ask for three tiers in the same email; the curve between them tells you more about the supplier than any single number does. If you are choosing between processes, start with CNC vs stamping vs sheet metal.
Put inspection and packing in the RFQ, not in the complaint
State the inspection level, who signs off on the first article, and what document arrives with the shipment. For dense metal parts, say how surfaces are protected against corrosion and how parts are separated so finished faces do not rub in transit. These requirements cost something when they are specified up front, and cost a great deal more when they are discovered after the goods arrive.
If the project involves more than one factory — a folded enclosure from one, machined bosses from another, stamped clips from a third — decide before ordering who consolidates and inspects before the parts share a carton. That sequence is covered in consolidating metal parts from multiple factories.
Five mistakes we see on first orders
- Sending a screenshot of a drawing instead of the source file, so dimensions cannot be read.
- Asking five suppliers to quote different revisions, then comparing the prices as if they were comparable.
- Leaving the material as “aluminium” and discovering later that the alloy cannot be anodised as expected.
- Approving a sample without a written note of what was approved, so the production run has no reference.
- Treating tooling as part of the piece price, then finding out who owns the die only when switching suppliers.
Frequently asked questions
Can a Chinese shop quote from a PDF drawing only?
It can give you a rough number, but not a reliable one. A 2D PDF cannot show the tool access, undercuts or setup count that drive machining time. Send a STEP or IGES model alongside the drawing and ask the supplier to confirm the revision it priced.
Do I need GD&T on every custom part?
No. Use a general tolerance standard for most features and apply geometric tolerances only to datums and mating surfaces. Over-specifying adds inspection time and cost without improving how the part fits. Ask the shop to price the tight tolerances separately so you can see what they cost.
What should a comparable quote show?
At minimum: unit price per quantity tier, tooling or programming charge, finishing, inspection, packaging, inland freight and the Incoterm. If any of these are missing, the quote is not comparable with another one. Ask for the factory invoice and service fee as separate lines where an agent is involved.
When should tooling ownership be written down?
Before the deposit, for any project with a stamping die, mould or custom fixture. State who paid for it, where it is stored, and what happens to it if you move production. This is far easier to agree at the RFQ stage than after the tool has been built.
What to do next
Save the 12 items above as a folder template and use the same structure for every enquiry. If you want a second pair of eyes before you send anything, our custom metal parts sourcing guide explains how we verify a factory and compare quotes on landed cost rather than unit price. You can also send your drawing for a free review of the RFQ pack — we will tell you what is missing before any money changes hands.
Editorial note for the site owner: replace the last call-to-action with your real contact or download URL before publishing. Any figures, lead times or certificate numbers added to this article must come from verified records; leave them out rather than estimating.