CNC Quoting
What Information Is Needed for an Accurate CNC Machining Quote?
An accurate CNC machining quote needs the current 3D model, controlled drawing, exact material, quantities, finish, critical requirements, inspection documents, delivery destination and required date. If any of these changes after pricing, cost and lead time may also change. Send functional context when you want the supplier to suggest a lower-risk or lower-cost alternative.
The Minimum Quote Package
| Information | Why the estimator needs it | Common ambiguity |
|---|---|---|
| 3D CAD model | Calculates geometry, stock, access and machining time | STEP and drawing show different revisions |
| 2D drawing | Controls tolerances, datums, threads, roughness and notes | General tolerance conflicts with feature callouts |
| Material | Affects stock cost, cutting strategy, stability and sourcing | “Aluminum” without alloy or temper |
| Quantity | Determines setup amortization and fixture strategy | No distinction between prototype and repeat batches |
| Finish | Adds process steps, thickness, masking and logistics | Color named without standard or sample |
| Inspection | Defines gauges, reporting and traceability effort | FAI or CMM requested only after production |
| Delivery terms | Separates manufacturing time from transit and import scope | “Urgent” without destination or arrival date |
Identify the Few Requirements That Control Function
Do not label every dimension critical. Mark the bores, sealing faces, mounting patterns, thread fits and datum relationships that determine assembly performance. State whether a tolerance applies before or after anodizing, plating or heat treatment. This lets engineering focus the process and inspection plan where failure matters.
Five Missing Details That Usually Stop Pricing
- No controlled revision: the estimator cannot know which geometry governs.
- Material family only: substituting 6061 for 7075 or 304 for 316L changes both performance and price.
- Undefined threads: diameter alone does not define pitch, class, handedness or usable depth.
- Finish without specification: thickness, masking and cosmetic acceptance remain unknown.
- No inspection scope: part price cannot include an undefined report or sampling plan.
A preliminary budget range may still be possible, but it should not be treated as a production commitment.
Example: Turning a Vague Request into a Quotable Package
Too vague: “Please quote 20 aluminum brackets, black anodized, tight tolerance, needed quickly.” Specify the governing process type or class, thickness or dimensional effect, masking and acceptance criteria for the actual project.
Quotable: “Quote 20 pieces of Part BR-104 Rev B from 6061-T6. Use the attached STEP and PDF drawing. Type II black anodize; mask the M6 threads and grounding face. The two locating bores and their position to Datums A and B are critical. Provide a material certificate and first-piece dimensional report. Deliver DAP to the stated postcode by the requested arrival date.”
The second request does not guarantee manufacturability, but it gives the supplier enough information to identify exceptions instead of pricing assumptions silently.
What Formexi Reviews Before Confirming a Quote
- File and revision consistency
- Feature access, tool reach and setup count
- Tolerance, datum and surface-finish compatibility
- Material and finishing availability
- Inspection feasibility and required records
- Packaging, shipping and schedule dependencies
Any capability, tolerance or lead-time statement remains subject to part-specific review.
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.