For CNC finishing, machining and assembly in Vietnam, agree who performs each operation, who verifies its output and who authorizes final release. One commercial contact can simplify coordination, but it does not establish that every operation is performed in-house or included in the quoted price.
This guide helps buyers define handovers between processes. Use it alongside the TDB turnkey manufacturing information, and confirm the actual scope for your project before ordering.
CNC finishing and assembly: create a responsibility plan
A quotation stating “machining, anodizing and assembly” still leaves important questions open. Which dimensions are checked after finishing? Who supplies purchased components? Does assembly include functional testing? Who reviews a rejected external-process lot?
Create a simple process matrix. Assign named contacts and actual evidence requirements for the order; the template below is a planning aid, not a description of services automatically included in every TDB project.
| Stage | Responsibility to confirm | Acceptance evidence to agree |
|---|---|---|
| Material receipt | Who purchases, verifies and maintains stock identity? | Required material evidence and job/lot relationship. |
| Machining | Who reviews the drawing, controls revisions and approves the setup? | Applicable in-process and dimensional results. |
| Finishing / treatment | Which processor performs the operation and who manages it? | Specified process records and checks in the returned condition. |
| Purchased items | Who approves and supplies inserts, fasteners or other components? | Approved references, quantities and identity where required. |
| Assembly | Who builds the assembly and to which controlled instructions? | Agreed fit, configuration and functional checks. |
| Final release | Who verifies completion and authorizes dispatch? | Accepted results, deviations, packing identity and release records. |
Ask which operations are in-house and which are external
Request a project-specific route rather than assuming the company’s service list describes the route for your part. Identify external operations early enough to review the proposed source, schedule dependencies and document requirements. Agree when a change of processor requires buyer notification or approval.
A quality-management certificate is one element of supplier review. It does not replace the project’s process requirements or part acceptance. ISO explains that certification is performed by external certification bodies; check the actual entity, site, scope and validity when using certification evidence.
Define acceptance before and after finishing
State the required delivered condition of functional surfaces, holes, threads and mating features. Identify any masking, appearance or verification requirements in the controlled specification. Resolve which characteristics are checked before a process and which require confirmation after it.
A supplier should not be expected to infer acceptance limits from the phrase “standard finish.” Use the surface-finish guide for the detailed specification questions. This article focuses on who owns the handover and evidence.
Make assembly requirements measurable
Provide the bill of materials, component revisions, assembly references and any customer-supplied items. Identify orientation, interfaces, approved consumables and required checks. If torque, cleanliness or functional performance is important, provide the applicable requirements and test conditions; do not leave the supplier to invent them.
Separate dimensional inspection from functional verification. A report for individual components does not by itself show that the complete assembly operates correctly. Define any test equipment, reference components, fixtures, acceptance limits and review responsibilities needed for the agreed test.
Keep lot identity through external handovers
Agree how parts are identified when they leave machining, return from finishing and enter assembly. Where a lot is split or combined, retain the relationships needed by the order. Packaging used between operations should protect the relevant surfaces and prevent mixing.
Clarify who checks quantities and condition at each handover. A discrepancy discovered only during final packing may be harder to resolve than one identified when the lot returns from processing. Include the required records in the quality-documentation request.
Resolve nonconformities before they become shipment decisions
Define who contains affected parts, records the issue, proposes a disposition and seeks approval. Rework, repair and use under a limited concession are different decisions. An external processor’s assurance that a part is usable should not substitute for the designated approval route.
After authorized rework, repeat the relevant verification and update the records. If buyer and supplier results differ, compare the drawing interpretation, datum setup, stage of measurement and methods before deciding the next action. The hypothetical inspection discrepancy case illustrates that discussion.
Review the complete scope before comparing price
Compare quotations on the same included operations, purchased items, testing, documentation, packaging and delivery conditions. Ask which activities are excluded or provisional. If an operation cannot be priced until a technical question is resolved, keep that dependency visible rather than treating an incomplete quotation as a finished offer.
A useful release review asks: are the correct parts assembled, are the required operations complete, is the evidence accepted, are any deviations authorized, and does the shipment identity match the records? Name who makes that decision and whether buyer approval is required before dispatch.
Buyer checklist for a multi-operation order
- List the included and excluded operations.
- Identify in-house and external responsibilities.
- Define pre-process and final-condition checks.
- Control purchased and customer-supplied components.
- Agree the rework, change and release process.
- Match the documentation pack to the shipped configuration.
Frequently asked questions
Does turnkey mean that every operation is in-house?
No. Ask the supplier to identify the actual process route and any external processors, and agree how changes will be controlled.
Should inspection happen before or after finishing?
Define checks at the relevant stages. Final acceptance must reflect the drawing and the condition in which the part will be delivered.
Does dimensional inspection prove an assembly works?
Not by itself. Agree any functional or fit verification separately, with clear methods and acceptance criteria.
Discuss your project with TDB Hanoi
Share your drawing package, finish specifications, assembly requirements and expected release records with TDB Hanoi. Ask for written confirmation of the proposed scope, process responsibilities and exclusions.
