Sep 18, 2026CNC Machining Guides

What Information Is Needed for an Accurate CNC Machining Quote?

Learn what drawings, 3D models, materials, quantities, tolerances, finishes, inspection requirements, and delivery information to include in a CNC machining RFQ.

machining quote
An accurate CNC machining quote depends on more than a part image or a short description. The manufacturer needs enough technical and commercial information to understand the geometry, material, quantity, quality requirements, secondary processes, and delivery expectations.
A complete request for quotation, or RFQ, helps reduce repeated questions and allows the manufacturing plan to be reviewed more efficiently. It also lowers the risk of quotations being based on different assumptions.
The following checklist explains what to include when requesting a quote for custom CNC machined parts.

1. Provide a 2D Technical Drawing

A 2D drawing communicates requirements that may not be fully defined in a 3D model.
Whenever possible, provide a clear PDF drawing containing:
  • Overall dimensions
  • Feature dimensions
  • Dimensional tolerances
  • Geometric tolerances
  • Datum references
  • Thread specifications
  • Surface roughness requirements
  • Material specification
  • Heat-treatment requirements
  • Coating or finishing requirements
  • Drawing revision
  • General notes
Critical dimensions should be identified clearly. Avoid applying unnecessarily tight tolerances to every feature because this may increase machining and inspection costs without improving the function of the part.
If the drawing contains proprietary information, provide only the information needed for manufacturing review and quotation.

2. Include a 3D CAD Model

A 3D model helps the manufacturer understand the complete geometry and evaluate features that may be difficult to interpret from individual drawing views.
STEP is commonly used for exchanging solid models between different CAD systems. Other neutral or native formats may also be reviewed when available.
Before sending the model, confirm that:
  • It represents the current revision
  • It matches the 2D drawing
  • All required features are included
  • Suppressed or unfinished features have been resolved
  • Separate components are clearly identified
  • The unit system is correct
When a 2D drawing and 3D model are both provided, state which document controls if there is a conflict.

3. Specify the Exact Material

Do not write only “aluminum,” “steel,” or “stainless steel.” Different grades can have different machining behavior, mechanical properties, availability, and cost.
Provide the complete material designation whenever possible, including:
  • Alloy or grade
  • Material standard
  • Temper or condition
  • Required hardness
  • Heat-treatment condition
  • Certification requirements
Examples of useful material information include a specific aluminum alloy and temper, stainless-steel grade, carbon-steel grade, copper alloy, or engineering-plastic grade.
If the material has not been finalized, explain the functional requirements and ask whether alternative materials can be reviewed. Do not approve a substitute until its performance and drawing requirements have been evaluated.

4. State the Required Quantity

Quantity affects raw-material planning, setup strategy, tooling, inspection scope, production method, and unit cost.
Include the quantity required for the current order and, when relevant:
  • Prototype quantity
  • First production quantity
  • Expected repeat-order quantity
  • Estimated annual demand
  • Required lot size
  • Whether partial deliveries are acceptable
Avoid requesting only a very large annual quantity if the immediate requirement is a small prototype batch. Ask for separate prototype and production pricing when both are relevant.

5. Identify Critical Tolerances

The quotation team needs to distinguish functional requirements from general dimensions.
Clearly identify:
  • Critical-to-function dimensions
  • Mating diameters
  • Fits and clearances
  • Hole-position requirements
  • Flatness and perpendicularity
  • Concentricity or runout
  • Datum relationships
  • Dimensions affected by finishing
  • Features requiring special measurement
Tighter tolerances may require additional operations, controlled setups, temperature considerations, specialized tooling, or more detailed inspection.
If a feature does not require a special tolerance, use an appropriate general drawing tolerance rather than assigning an unnecessarily strict value.

6. Define Surface-Finish Requirements

Surface finish can refer to machined roughness, visual appearance, or a secondary treatment. These are different requirements and should be stated separately.
Provide details such as:
  • Required surface roughness
  • Surfaces to remain as machined
  • Cosmetic or non-cosmetic areas
  • Anodizing
  • Plating
  • Passivation
  • Coating
  • Polishing
  • Heat treatment
  • Deburring and edge requirements
  • Areas that must be masked
Color descriptions alone may not be sufficient for controlled finishes. If appearance is important, include an approved standard, sample, or other acceptance requirement.
Secondary processing can affect dimensions. Identify any dimensions that must be controlled before or after coating.
Learn more about our Surface Treatment Solutions.

7. Explain Inspection and Documentation Requirements

Inspection requirements should be defined before quotation, especially when the customer requires more than standard dimensional verification.
Possible requirements include:
  • First-article inspection
  • Dimensional inspection report
  • Material certificate
  • Heat-treatment certificate
  • Coating certificate
  • Certificate of conformity
  • Measurement of specific critical dimensions
  • Sampling plan
  • Full inspection of selected features
  • Traceability or lot identification
  • Special packaging records
Provide the required report format or customer inspection form when one must be followed.
Do not wait until production is complete to request extensive documentation that was not included in the quotation.
Learn more about our Quality Control and Inspection.

8. Include the Target Delivery Requirement

State when the parts are required and where they need to be delivered.
Useful delivery information includes:
  • Requested delivery date
  • Prototype testing schedule
  • Whether partial shipment is acceptable
  • Delivery destination
  • Preferred shipping method
  • Special export or packaging requirements
A requested date should be treated as a planning requirement, not as a confirmed lead time, until the drawing, material, quantity, processes, and production capacity have been reviewed.
If the schedule is flexible, say so. Flexibility may allow a more practical manufacturing plan.

9. Describe the Part Application When Relevant

You do not need to disclose confidential system details, but limited application information can help the manufacturer understand functional risks.
Useful information may include whether the part is:
  • A structural component
  • A rotating component
  • A bearing or bushing interface
  • A sealing surface
  • A cosmetic part
  • Exposed to heat, corrosion, or wear
  • Used in an assembly with critical fits
  • Intended for prototype testing or production
Application context does not replace the drawing. It helps explain why certain dimensions, materials, or finishes are important.

10. Confirm the Drawing Revision

Revision control is essential when multiple files are exchanged.
Before submitting an RFQ:
  • Confirm the current drawing revision
  • Use consistent filenames
  • Remove obsolete files from the package
  • Make sure the drawing and model match
  • Identify any changes from the previous quotation
  • State whether existing pricing must be revised
When a drawing changes after quotation, highlight the change rather than sending a new file without explanation. Even a small revision may affect material, tooling, machining time, inspection, or finishing.

Common RFQ Problems That Delay Quotation

A quotation may be delayed when the RFQ contains:
  • Only a photograph without a drawing
  • A 3D model with no tolerances
  • A drawing with no material specification
  • No required quantity
  • Conflicting 2D and 3D files
  • Missing thread specifications
  • Unclear surface-finish requirements
  • No indication of critical dimensions
  • An outdated revision
  • An unrealistic delivery date with no priority explanation
  • Requests for certification or inspection added after pricing
Reviewing the RFQ package before submission can prevent many of these problems.

CNC Machining RFQ Checklist

Before sending your enquiry, confirm that you have included:
  • 2D PDF drawing
  • 3D CAD model
  • Current revision
  • Material grade and condition
  • Required quantity
  • Critical tolerances
  • Surface finish and secondary processes
  • Inspection and documentation requirements
  • Delivery destination
  • Target delivery date
  • Contact name and company information
If some information is not yet available, identify it as pending instead of allowing the supplier to make an assumption.

Protecting Confidential Project Information

Send only the project information required for manufacturing review. Remove unrelated customer names, internal pricing, or unnecessary assembly information from the RFQ package.
If confidentiality documentation is required before file exchange, mention this in the initial enquiry.
Generic website illustrations should not be treated as proof of a specific customer project. Manufacturing feasibility and quotation should always be based on the submitted drawing and project requirements.

Request a CNC Machining Quote

Zync Precision reviews custom CNC machining projects according to customer drawings, materials, quantities, tolerances, finishing, inspection, and delivery requirements.
For an initial review, use our Contact Page or email emily@zyncprecision.com.
Include the 2D drawing and 3D model where available. If your files are too large to send by email, contact us first to arrange an appropriate transfer method.