RFQ Package for Precision Machined Components: The Complete Checklist
Direct answer: An RFQ package for precision machined components is the full set of documents a buyer sends to vendors so they can price a part accurately. At minimum it includes: a dimensioned 2D drawing, a 3D STEP model, material specification, tolerance standard callout, surface finish requirements, quantity and delivery data, special process list, and inspection or FAI requirements. Missing any one of these triggers clarification rounds that inflate lead time and quote price.
When the Quote Comes Back Wrong
A procurement engineer sends drawings to three machine shops on a Monday. By Thursday, one quote is 40% higher than the others, one vendor is asking six clarification questions, and the third has priced mild steel when the part is 17-4 PH stainless. None of this is unusual — it is the predictable result of an incomplete RFQ package.
Vendors price what they can see. If a callout is missing, they assume the easiest interpretation. If a file is ambiguous, they pad the quote for risk. The cost of a poorly assembled machining RFQ document list is not just slow response time — it is wrong parts arriving at incoming inspection.
What Is Actually at Stake
Precision machined components often carry tolerances of ±0.01 mm or tighter. A single missing datum reference, an unspecified heat treatment, or an unstated surface finish requirement can render a batch unusable. Rework at a CNC shop for a mid-complexity turned part can easily run two to three weeks. For aerospace or medical parts, a non-conforming first article triggers a full corrective action cycle.
Beyond quality, an incomplete RFQ forces your engineering team into reactive email threads instead of forward-looking programme work. Getting the RFQ package right on the first send is not administrative perfectionism — it is direct cost control.
The Complete RFQ Checklist for CNC Parts Procurement
The following checklist is structured in the order a vendor's estimating engineer reads a package. Work through it before every RFQ release, regardless of part complexity.
1. Engineering Drawing (2D)
Send a PDF of the released, revision-controlled drawing. The drawing must carry a title block with part number, revision level, drawing standard (ASME Y14.5-2018 or ISO 8015/GPS), and the name of the approving engineer. All dimensions must be fully defined — no assumed symmetric tolerances unless explicitly stated as a general tolerance block per ISO 2768-m or equivalent.
Every feature that matters to function should carry an explicit tolerance. For positional callouts, use GD&T feature control frames per ASME Y14.5-2018 rather than coordinate plus/minus tolerances where possible — a true position callout of ⌀0.05 mm at MMC communicates far more than ±0.025 mm in X and Y separately.
Balloon your drawing before you send it. A ballooned drawing with numbered characteristics signals to the vendor that you intend to verify every dimension at first article. It also accelerates your own incoming inspection because the balloon numbers map directly to inspection report rows. See the guide to ballooning a drawing for a primer on the technique.
2. 3D Model (STEP File)
Attach the STEP file (ISO 10303 AP214 or AP242). STEP is vendor-neutral; the shop's CAM programmer can import it directly into Mastercam, Fusion 360, or any other toolpath software without owning your CAD licence. IGES is acceptable as a fallback but loses parametric thread data, which forces the vendor to infer thread form from the 2D drawing alone — one more source of ambiguity.
If the part is an assembly, include a STEP assembly with all referenced components. The vendor needs to understand clamp faces, datum surfaces, and assembly interfaces to plan fixturing correctly. You can open and verify your STEP file in a browser before sending, confirming geometry and checking the auto-generated BOM matches your drawing.
3. Material Specification
State the alloy, grade, and controlling standard — not just a common name. "Aluminium 6061-T6 per ASTM B209" is unambiguous. "Aluminium alloy" is not. Include:
- Material designation and temper (e.g., SS 316L, Ti-6Al-4V ELI, EN 1.4404)
- Controlling standard (ASTM, AMS, EN, JIS, IS as applicable)
- Whether a material test report (MTR) or certificate of conformance (CoC) is required with delivery
- Any restricted substances exclusions (RoHS, REACH, DFARS for US government work)
For aerospace parts, AMS material specifications (e.g., AMS 2770 for heat treatment of aluminium) are frequently required alongside the raw material call-out. State them explicitly in the RFQ so the vendor prices the right heat lot traceability.
4. Geometric Tolerances and Standards Reference
State the governing tolerancing standard on the drawing and in the RFQ cover sheet. Do not assume the vendor will default to the same standard as your design team.
| Standard | Typical application | Key note |
|---|---|---|
| ASME Y14.5-2018 | North American OEMs, aerospace, defence | Rule #1 (perfect form at MMC) applies unless waived |
| ISO 2768-m/k | General industrial, European supply chains | General tolerance; medium class covers ±0.1 mm on dims ≤30 mm |
| ISO 8015 + GPS | ISO-aligned engineering drawings | Independence principle — form not controlled by size unless stated |
| JIS B 0419 | Japanese OEM supply chains | Similar structure to ISO 2768 |
For a deeper look at GD&T symbols and reading feature control frames, the CadNexa GD&T guide covers all 14 symbols with worked examples.
5. Surface Finish Requirements
Specify Ra in µm, the measurement standard (ISO 1302 or ASME Y14.36M), cutoff length, and lay direction where functional. A simple worked example: a hydraulic valve bore specified at Ra 0.8 µm, cutoff λc = 0.8 mm, lay circumferential — that is a complete callout. "125 finish" written alone on a drawing leaves the vendor uncertain whether you mean 125 µin Ra (≈3.2 µm), which is a completely different machining requirement.
List any areas that are exempt from the general surface finish requirement (e.g., raw stock faces, internal non-functional pockets).
6. Special Processes List
Special processes must be called out explicitly because they affect make-or-buy decisions at the vendor. A shop may have turning and milling in-house but subcontract anodising, plating, or heat treatment. Common special processes to specify include:
- Heat treatment (e.g., hardening to 58–62 HRC per ASTM A29, annealing per AMS 2750)
- Surface treatment (hard anodise per MIL-A-8625 Type III, electroless nickel, passivation per ASTM A967)
- Thread rolling vs. thread cutting (state preference where fatigue life matters)
- NDT requirements (dye penetrant per ASTM E1417, magnetic particle per ASTM E1444)
- Cleaning and cleanliness specification (e.g., NAS 1638 cleanliness class for hydraulic parts)
7. Quantity, Delivery Schedule, and Packaging
State annual volume, initial order quantity, and delivery milestones. Vendors price differently for 5-off prototypes versus 500-off production. Include:
- First article quantity (typically 1–3 pieces) and production quantity
- Required delivery date and Incoterms (FCA, DAP, DDP)
- Packaging requirements — are parts to be individually wrapped? Coated with rust preventive VCI film? Placed in ESD trays?
- Labelling format (part number, revision, batch/lot number, date code)
8. Inspection and FAI Requirements
This is the section most often omitted from a machining RFQ document list, and its absence guarantees a dispute at first article. State clearly:
- Whether a First Article Inspection report is required and to which standard: AS9102 Rev C (aerospace), PPAP Level (automotive — see AS9102 vs PPAP comparison), or a customer-specific format
- Which characteristics require dimensional reporting (all ballooned dims, or critical characteristics only)
- Whether a CMM report, surface roughness trace, or hardness certificate is needed
- Acceptable sample size for FAI (e.g., 1 of 5 production parts per AS9102 Rev C clause 1.1)
- Whether the vendor must submit the FAI report for approval before shipping the batch
If you are using AS9102 Rev C, the FAI covers three forms: Design Accountability, Product Accountability, and Characteristic Accountability. Specifying this upfront prevents vendors from submitting a generic dimensional report that omits material certifications.
9. Commercial and Legal Terms
The RFQ cover sheet should include quote validity period requested (typically 30–60 days), payment terms expectation, NDA status, and any export control classification (ECCN or ITAR for US-controlled parts). If the part is ITAR-controlled, the vendor must be a registered US manufacturer — this cannot be discovered after award.
10. Secure Distribution Method
Emailing a PDF to ten vendors on a BCC list is not a distribution method — it is a document control failure. Once a file is emailed, you cannot revoke it, track who opened it, or confirm which revision each vendor quoted from. Use a system that generates vendor-specific URLs with password protection, expiry dates, and an audit trail.
Common Mistakes That Kill Quote Accuracy
Sending a drawing without a revision number. Vendors quote what they receive. If you issue Rev B three days later by email reply, there is no guarantee the updated file reaches every estimator. Always embed revision in the filename and title block.
Specifying a general tolerance without a class. Writing "tolerances per ISO 2768" without stating the class (fine, medium, coarse, very coarse) gives the vendor no numerical basis. Medium class (m) is the most common default for machined parts — state it explicitly.
Omitting datum references. A position tolerance of ⌀0.05 mm means nothing without a datum reference frame. If the drawing does not specify which surfaces establish A, B, and C datums, the vendor will fixture the part differently from your CMM setup and every positional measurement will disagree.
Listing material by trade name only. "Delrin" or "Inconel" without a grade and standard leaves room for substitution. Specify "Inconel 625 per ASTM B446, UNS N06625" if that is what you need.
Forgetting to state units. An international supply chain sees both metric and imperial drawings. If your drawing uses inches, state it in the title block. If it uses millimetres, state that too. ASME Y14.5-2018 drawings default to the unit of the dimension values, but that assumption is not universal.
Frequently Asked Questions
What documents must be included in an RFQ package for precision machined components?
A complete RFQ package should include: dimensioned 2D engineering drawing (PDF), 3D model (STEP preferred), material specification with grade and standard, geometric tolerancing callouts per ASME Y14.5-2018 or ISO 2768, surface finish requirements, special process list, quantity and delivery schedule, and inspection or FAI requirements. Missing any element forces the vendor to assume or ask, both of which inflate lead time and quote error.
What 3D file format should I send in a machining RFQ?
STEP (ISO 10303) is the preferred neutral format for CNC machining RFQs. It preserves geometry, thread features, and assembly context without requiring the vendor to own your CAD licence. IGES is acceptable as a fallback but carries less metadata and loses parametric thread information.
How do I specify surface finish in a machining RFQ document?
Use Ra values in micrometres (µm) or microinches (µin) referenced to ISO 1302 or ASME Y14.36M. State the measurement cutoff length and direction of lay where critical. A typical machined surface is Ra 1.6 µm (63 µin); a ground bearing bore may be Ra 0.4 µm (16 µin). Avoid legacy "N-number" or "RMS" callouts without conversion to Ra.
Should I include an FAI requirement in a standard machining RFQ?
Yes. For any new part or drawing revision, stating FAI requirements upfront prevents disputes at first delivery. Specify the standard (AS9102 Rev C for aerospace, PPAP Level 3 for automotive, or ISO for general industrial), which characteristics need to be measured, and the expected sample size. This lets the vendor price inspection time correctly and avoids surprises at incoming QC.
How do I protect my drawing IP when sharing an RFQ with multiple vendors?
Use a secure sharing method that generates unique, password-protected URLs per vendor with an expiry date and an audit trail showing who accessed the file and when. Avoid emailing raw PDF files to distribution lists — once sent, they cannot be revoked, and you have no record of which revision each vendor quoted. CadNexa's Secure RFQ System handles this with signed vendor URLs, password control, and expiry settings.
Conclusion
A complete RFQ package for precision machined components is not a bureaucratic exercise — it is the technical brief that determines whether your vendor prices the right part, to the right standard, at the right quality level. Ten items, assembled once, prevent weeks of rework. The checklist above covers every document a machine shop estimator needs from the first look at a drawing to the moment they quote a price.
The two areas that most often derail machining RFQs are drawing ambiguity (solved by ballooning and explicit tolerance callouts) and insecure file distribution (solved by controlled vendor URLs rather than email attachments). Both are addressable before the RFQ goes out.