How are CNC aluminum parts quoted? Drawing and inquiry checklist

Equal weight does not mean equal work

A plate with a few through holes and an enclosure with deep pockets, thin walls, side holes and multiple cutting directions may weigh the same but require different toolpaths, setups and machining time. A quote needs geometry and dimensions, not just a kilogram weight.

Specify material grade and condition. Do not replace an explicit grade with the generic label aluminum alloy. If substitutes are allowed, first agree use and performance requirements. For customer-supplied stock, state blank sizes, quantities and usable allowance.

Distinguish critical tolerances from general dimensions

Mating holes, locating faces and assembly datums usually deserve specific attention. Applying the same tight tolerance to every dimension can increase machining and inspection effort without solving the actual fit problem. The design owner should identify functional dimensions and ordinary requirements.

Protolabs highlights details such as threads, hole geometry, surface lettering and machinable features in its design guidance. This reference encourages attention to geometry and process; it does not imply XCR adopts that supplier's equipment specifications, prices or lead times.

Specify finishing together with dimensions

Anodizing, blasting, polishing and painting are different operations. Color, gloss, cosmetic surfaces and masked areas affect process planning. Confirm post-treatment dimensions and fits before machining ends. Appearance samples or clear acceptance criteria reduce ambiguity about approximate color matches.

1. 3D model, critical 2D dimensions and consistent revision numbers.
2. Material grade and stock or customer-supplied material conditions.
3. Prototype quantities and expected production quantities, quoted separately.
4. Datums, critical tolerances, thread specifications and fit requirements.
5. Cosmetic surfaces, permitted tool marks and deburring requirements.
6. Finish, color, masking and post-treatment inspection requirements.
7. Dimensional records, sampling or other agreed inspection deliverables.
8. Packaging, lead time and parts requiring associated assembly.

From first article to production: more than unit price

First articles and small runs carry programming, setup and process-confirmation work. Production quotes must also consider repeatability, in-process checks and scheduling. Do not simply multiply prototype price by volume or use a low production price to judge the fair cost of a single trial.

Agree first-article approval criteria and keep drawing, program and inspection revisions aligned when changes occur during production. Lead time depends on complete inputs, materials, scheduling and finishing steps. This guide explains quotation inputs; formal prices and delivery dates belong in the project agreement.

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