Machining & Assembly · Component review guide · Litian Yunde
Map the surfaces by function. Original explanatory schematic; not to scale and not a product test result.
A finishing drawing should identify the areas to coat, bond, mask or leave untouched. A single colour or gloss instruction cannot describe every functional surface. Use a zone map and define the order of operations so coating does not silently change an adhesive or fit interface.
Give each zone a clear purpose
Mark the visible finish zone, bond zone, sliding face, electrical contact or identification area as separate features where applicable. State whether overspray is allowed at a boundary and how that boundary is inspected. Keep masking dimensions tied to datums. Instructions such as “keep the back clean” are difficult to reproduce on a complex or handed part.
Review the sequence before finishing
A surface intended for bonding needs the preparation required by the chosen adhesive and material system. Confirm whether bonding precedes or follows painting and who controls the surface between operations. Masking tape removal, handling and storage should not undermine the approved preparation. A visually neat coating boundary is useful but does not establish adhesive compatibility or cleanliness.
Check after the last relevant operation
Inspect the finished part for zone position, edge quality and any interference with mating components. Record the coating system where it affects a controlled interface. If a part is repainted, revisit the fit and bond zones before accepting it. Rework should restore the approved configuration rather than adding successive layers without checking their effect.
Example: a cover bonded to mounting pads
The outside of a cover requires a cosmetic coating, while small internal pads require an adhesive process. The drawing gives each pad an identified keep-clear region and specifies which operation happens first. The sample review photographs these regions before bonding and checks the final coating boundary. The record is specific to the approved finish and adhesive systems.
Illustrative scenario, not a customer case or reported production result.
Details to agree before ordering
| Review item | Record to agree |
|---|---|
| Zone map | Named finish, bond and keep-clear areas. |
| Boundary control | Datum-based location and allowed edge variation. |
| Process sequence | Painting, preparation, bonding and handling order. |
| Rework rule | How zones and interfaces are restored and rechecked. |
Questions buyers ask
Is masking sufficient surface preparation for bonding?
No. It preserves an area but does not replace the adhesive supplier’s preparation requirements.
Should hidden surfaces receive the same coating?
Only if the specification calls for it and the coating is compatible with their function.
Technical background and related reading
Background resource: WEST SYSTEM: Surface Preparation. The project checklist and example above are editorial guidance; this reference does not certify a Litian Yunde component.
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Review your component with Litian Yunde
Share the drawing revision, intended application and the interface or inspection question you need to resolve. The quoted construction and acceptance requirements are confirmed for the specific project.