Most of a product’s manufacturing cost is fixed before production starts. Part count, material, tolerance, assembly sequence and test strategy are all design decisions, and each of them has a cost consequence that is difficult to change later.
Design for assembly, not only for manufacture
A design can be manufacturable and still be expensive to assemble. Every screw, cable and connector adds a station, a tool and a chance for error. Reducing part count and designing snap fits where appropriate lowers cost more reliably than negotiating piece price.
Review the assembly sequence on paper with the people who will build it. A step that requires three hands or a special fixture is a cost that will appear on every unit.
Tolerance strategy
Tolerance is a cost driver: tighter tolerances require better tools, slower machining and more inspection. Apply tight tolerances only where the function requires them, and analyse the stack-up at the interfaces that matter.
A common failure is a cosmetic gap that only appears when two parts are at opposite ends of their tolerance bands. Stack-up analysis at the extremes catches this before tooling.
The tooling gate
- Mechanical fit confirmed with the actual PCB, battery, connector and cable.
- Antenna performance measured in the final enclosure.
- DFM review completed with the molder, including draft, gate and ejection.
- Assembly sequence and fixture requirements documented.
- Production test specification and test points defined.
- Certification requirements confirmed for every destination market.
PCBA and test strategy
Board assembly should include inspection appropriate to the technology: AOI as a baseline, X-ray where hidden joints exist. Functional test should exercise the real interfaces, not only power-on.
Programming and calibration belong in the test flow. A board that is programmed at final assembly adds a handling step and a risk of mixing firmware versions.
First article and production release
The first article approval is the formal point where design intent meets production reality. Measure the dimensions that matter, check appearance against the agreed standard, and document any concession.
Production then runs against a frozen process. Changes after release should go through the same review, otherwise the approved first article stops representing what is shipped.
Working with one partner across the chain
When design, tooling, PCBA and assembly are handled by separate suppliers, the interfaces between them become the schedule risk. A single partner does not remove the difficulty, but it removes the ambiguity about who owns a problem when a part does not fit or a test fails.
Related engineering
If this topic is close to a decision you are making, send the requirement and we will respond with a technical view rather than a sales brochure.
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