Surface Finishing for CNC Machined Parts

Finishing changes appearance, corrosion resistance, wear behavior and sometimes final dimensions. Select the process from the material and function, then define color, gloss, masking, cosmetic acceptance and whether dimensions apply before or after finish.

Finish selection matrix

As-machined: no added coating; tool marks and edge condition should be defined.
Bead blasting: uniform matte texture; media, pressure and handling affect appearance.
Anodizing / hard anodizing: aluminum oxide layer; alloy, color and thickness affect consistency and dimensions.
Black oxide, zinc or electroless nickel: steel-compatible options with different corrosion, wear and thickness behavior.
Passivation / electropolishing: stainless-steel treatments selected for cleanliness, corrosion behavior or smoothing.
Powder coating / painting: thicker cosmetic or protective coatings needing masking and allowance.
Polishing: mechanical surface refinement; direction and acceptance sample should be agreed.
Heat treatment / nitriding: material-property processes, not cosmetic finishes, and require grade-specific review.

Masking and tolerance planning

Threads, bearing seats, electrical contacts, sealing faces and precision bores may need masking. Coating buildup can reduce clearance or change fit; blasting and polishing can soften edges. Drawings should state which dimensions apply after finish and which areas are cosmetic.

Verification

Depending on the process, verification may include visual comparison, color range, gloss, coating thickness, adhesion, hardness or supplier certificate. Availability is confirmed with the selected finish partner; no universal certification is implied.

RFQ information to provide

  • 3D model plus a revision-controlled 2D PDF drawing.
  • Material grade, condition, quantity and delivery destination.
  • Critical dimensions, datums, fits, threads and surface roughness.
  • Heat treatment, coating, masking, cosmetic or packaging requirements.
  • Requested material certificates, dimensional report or first-article scope.

Frequently asked questions

Provide controlled 3D and 2D data, material and condition, quantity, finish, critical characteristics, inspection documentation and target delivery. State any approved alternatives or supplier restrictions.

Tolerance is reviewed by feature against size, geometry, material, setup, process sequence and measurement. The quotation records assumptions; it does not extend one tight value to every dimension.

Selected dimensional reports, first-article records or material documents can be included when the required scope and format are stated before quotation.

Not necessarily. Machine ownership and partner-supported processes are distinguished during capability confirmation where they affect confidentiality, quality or delivery.

Upload the model, drawing and project requirements through the Request a Quote form. Complete RFQs are targeted for review within one business day, subject to complexity and clarification.

Engineering review and next step

Content reviewed for manufacturing accuracy by the QuickCNCs engineering coordination team. Updated August 29, 2026.

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