Buyer Preparation Guide
How to Prepare a CNC Machining RFQ
Prepare one RFQ package containing the current 3D model, controlled 2D drawing, material, quantity, finish, critical tolerances, inspection documents, delivery destination and required date. Explain the part’s function and project stage when engineering alternatives are allowed. Complete information reduces clarification and makes supplier quotations comparable.
Step 1: Send Geometry and Controlled Requirements Together
The 3D model defines geometry; the 2D drawing controls tolerances, datums, threads, roughness, finish and notes. Ensure both use the same part number and revision. Do not send several versions without identifying which controls production.
Step 2: Define Material Precisely
| Weak request | Better request |
|---|---|
| Aluminum | 6061-T6 to specified standard, MTC required |
| Stainless | 316L, product form/standard stated, no substitution |
| Plastic | POM-C black, supplier certificate required |
| Steel, hardened | 4140, starting condition and final hardness specified |
Step 3: Separate Prototype and Production Quantities
Provide current quantity, expected batch sizes and annual demand. A one-off prototype and a repeat production program require different fixtures, inspection, supplier controls and pricing.
Step 4: Identify Functional Requirements
- Dimensions that control fit, sealing, motion or alignment
- Datum and GD&T relationships
- Thread standard, class and usable depth
- Surface roughness and cosmetic A/B/C zones
- Finish thickness, color, masking and test
- Cleaning, traceability, labeling and packaging
Step 5: Request Quality Documents Before Production
State MTC, CMM, FAI, full-dimensional, CoC, finish certificate, PPAP or other reports in the RFQ. Some evidence cannot be reconstructed after stock is consumed or parts are shipped.
Step 6: Clarify Commercial and Delivery Terms
Provide destination, required arrival date, Incoterm, freight preference, currency and payment constraints. Confirm whether quoted lead time begins after PO, payment, material or drawing approval.
Example RFQ Summary
- Part: Motor Mount Rev C
- Material: Aluminum 6061-T6, MTC required
- Quantity: 5 prototypes; 200 per batch after approval
- Finish: Black Type II anodize; mask bearing bore and grounding face
- Critical: Bore fit and position to Datums A|B|C
- Inspection: FAI on prototype; standard report on batches
- Delivery: DAP, Munich, required arrival date shown
- Notes: DFM alternatives allowed before Rev C is frozen
From How to Prepare a CNC Machining RFQ Requirements to a Controlled Manufacturing Plan
The purchasing issue behind How to Prepare a CNC Machining RFQ is that buyers can overpay or lose datum consistency when a process is chosen from a machine label instead of the part geometry; as a result, unnecessary setups or an unjustified high-end route can add cost without improving the functional result. Our response is to compares rotational versus prismatic geometry, feature access, datum relationships, workholding, batch size and measurement access before selecting milling, turning or a combined route. The objective is to protect assembly and validation schedules while reducing preventable scrap, rework and supplier-change risk.
For the How to Prepare a CNC Machining RFQ buying decision, before we confirm price or delivery, the buyer should send the 2D drawing and 3D model, overall size, material state, critical datums and tolerances, quantity, finish and inspection documents. If a requirement cannot yet be verified, we keep it as an open condition instead of presenting it as a guaranteed result.
Complete RFQ Inputs Before Supplier Comparison
| Input group | Information required before price and lead-time confirmation |
|---|---|
| Controlled files | 2D drawing, 3D CAD model, part number, drawing revision, units and any conflict between model and drawing |
| Material | Exact grade and standard, condition/temper/hardness, stock-form limits, certificate and lot-traceability requirements, and substitution approval rule |
| Demand | Prototype quantity, first batch, order quantity, annual demand, repeat schedule and target delivery date |
| Functional requirements | Critical dimensions, dimensional tolerances, GD&T and datums, threads, fits, surface roughness parameter and location, sealing, motion or assembly requirements |
| Special processes | Heat treatment, surface treatment or surface finish type/class/thickness/color, masking, post-process dimensions and approved-source requirements |
| Quality | Inspection requirements and inspection plan, frequency, first-article hold point, quality-document format, material certificate, special-process certificates and customer-specific or regulatory industry requirements |
| Commercial and logistics | Packaging requirements, labeling, cleanliness, delivery destination, Incoterm if required, NDA or confidentiality requirements and acceptable DFM changes or written-approval scope |
Missing information should be recorded as an open clarification, not converted into an assumed high-precision or premium-documentation requirement.