A complete CNC machining request for quote does not need to be long. It needs to remove the assumptions that could change the manufacturing method, inspection plan, price, or delivery date. When two suppliers receive different technical baselines, their prices are not truly comparable.
The 12-point CNC machining RFQ checklist
- Send the 3D model. STEP or Parasolid gives the shop usable geometry for CAM, stock evaluation, and feature review. Native CAD is helpful when available, but a neutral model prevents software-version problems.
- Include the matching 2D drawing. The model describes shape; the print carries tolerances, datums, finishes, notes, revision, and requirements that should not be inferred from geometry.
- Identify the governing revision. Put the part number and revision in both the filename and the RFQ. If the model and drawing conflict, state which controls or correct the package before release.
- Specify the exact material and condition. “Aluminum” or “stainless” is not enough. State grade, temper or heat-treatment condition, approved specifications, and any domestic-source or traceability requirements.
- Define prototype, release quantity, and annual usage. Quantity changes workholding, bar or plate purchasing, programming allocation, inspection sampling, and whether automation makes sense.
- Mark the functional and critical features. Tell the shop what locates, seals, rotates, mates, or carries load. This lets manufacturing protect the features that matter instead of treating every dimension as equally risky.
- Use a complete datum and GD&T scheme. Datums should reflect how the part functions and can be inspected. Avoid disconnected controls or duplicated coordinate dimensions that create competing interpretations.
- Call out surface finish only where required. A blanket fine-finish note can add cycle time to every face. Identify sealing, bearing, cosmetic, or fatigue-sensitive surfaces individually.
- List secondary operations. Anodize, plating, passivation, heat treatment, grinding, lapping, marking, assembly, cleaning, and masking can change dimensions and schedule.
- Define the documentation package. State whether you need a certificate of conformance, material certifications, first article inspection, CMM report, process certifications, PPAP elements, or serialization.
- Flag controlled or confidential data before transfer. Tell the supplier when an NDA, export-control process, U.S.-person restriction, or customer-specific portal must be in place before drawings are shared.
- Give the commercial target. Include the required delivery date, ship-to location, packaging needs, target price when useful, and whether alternate materials, finishes, or tolerance changes may be proposed.
What file package should you send?
| File or input | What it controls | Common problem |
|---|---|---|
| STEP / Parasolid model | Machined geometry and CAM baseline | Model does not match drawing revision |
| PDF drawing | Tolerances, datums, notes, finishes, quality requirements | Critical dimensions are implied but not identified |
| RFQ cover information | Quantity, timing, usage, delivery, commercial assumptions | Prototype quantity supplied with no production forecast |
| Specification package | Material, special processes, customer requirements | Referenced specifications are missing or obsolete |
What usually delays a CNC quote?
The slowest RFQs force the estimator to guess. Common delays include an unspecified material condition, a model and drawing at different revisions, no quantity, uncontrolled “tight tolerance throughout” notes, missing finish requirements, and an unrealistic delivery date with no indication of which requirement can move.
Another frequent problem is a print that describes inspection but not function. If a bore is critical because it carries a bearing, say so. The shop can then recommend an appropriate process, inspection frequency, and allowance before finishing.
How to make supplier quotes comparable
Send every supplier the same revision and ask each to list assumptions and exclusions. Compare more than unit price: material and process certifications, inspection scope, first-article handling, nonrecurring charges, lead time, packaging, shipping terms, and whether finishing is included.
A low quote built on a different inspection plan or material assumption is not a lower price for the same part. It is a different offer.
How Procut-CNC reviews an RFQ
We review geometry, process fit, workholding, material availability, critical features, inspection access, secondary operations, and documentation before pricing. If a drawing change could remove a setup or protect a difficult tolerance, we flag it during DFM review instead of hiding the risk in the price.
Ready to use the checklist? Start a Procut-CNC RFQ for non-controlled files. For controlled, large, or otherwise sensitive packages, call (612) 851-6772 for approved transfer instructions. Do not email technical files.