Between the approved sample and the tenth production batch, small changes accumulate: a different adhesive, a revised label, a slightly different gloss. A golden sample is the control that makes those changes visible before they become customer complaints.

This article covers what a golden sample is, what it should contain, and how it is used at inspection.

What is a golden sample?

The approved production reference.

A golden sample is a unit signed off by the buyer and the factory that represents the agreed specification, kept sealed and used to judge subsequent production batches.

It is not a prototype: it is a unit built to the production process, with the final label, packaging and accessories. Its purpose is comparison: a batch is inspected against it for appearance, dimensions, labelling and functional behaviour.

Both parties keep a sealed sample. Where the two diverge, the divergence itself is information about how the sample was stored or handled rather than about the product.

Pre-production, golden and limit samples

Three sample types serve different purposes. A pre-production sample confirms the design; a golden sample confirms the production specification; and limit samples define the acceptable extremes of a cosmetic characteristic such as colour or gloss.

For a charger line, limit samples are particularly useful on enclosure finish and on printed markings, where two acceptable units can look different under different lighting.

What to seal in the sample pack

The pack should contain the product, its cable, its packaging and its documentation, all in the approved version. Sealing the pack with a signed label and a date, and listing the contents, prevents the most common failure: a sample that no longer matches what was approved because a component was replaced.

Measurement record: parameters and tolerances

A sample without measurements is only a visual reference. The record should list the parameters that matter: output behaviour at defined loads, surface finish, colour reference, label placement and enclosure dimensions with tolerances.

Those parameters then become the inspection lines for each batch, which is what turns the sample into a production control rather than an artefact.

Change control: what invalidates a sample

Any change to the BOM, the tooling, the label, the packaging or the site invalidates the golden sample and requires a new approval. Documenting that rule prevents the situation where a production change is made for cost or availability reasons and the sample quietly becomes obsolete.

For multi-site production, each site keeps its own sealed sample, and the two are compared periodically as part of the cross-site control.

Using the sample at inspection

At incoming or pre-shipment inspection, the inspector compares the batch against the sample under defined lighting, checks the measured parameters against the record, and documents any deviation with photographs. The comparison is what makes the sample operational.

WECENT’s quality control process includes incoming material verification, functional testing, hi-pot pressure testing and load aging, with per-batch inspection reports. The golden sample record is part of that file for each charger programme, and it is available to buyers under NDA through the OEM/ODM programme.

Why the gate is cheaper than the alternative

A production batch that deviates from the approved specification is discovered either at inspection or by customers. The first costs a delay; the second costs returns, reviews and, in a regulated market, a compliance question.

The sample gate costs a few hours of administrative work. That asymmetry is why it is worth doing even on a small programme, and why the record should be kept with the batch documentation rather than in an inbox.

The sample gate also creates a reference for supplier discussions. When a batch deviates, the conversation moves from opinion to comparison, and the remedy becomes specific: which parameter moved, by how much, and what change caused it. That shortens both the diagnosis and the corrective action.

For programmes that ship to several markets, the same record supports the compliance file. Efficiency and EMC documentation for the destination market (Regulation (EU) 2019/1782 and 47 CFR Part 15) attaches to a model built to an approved specification, and the golden sample record is what demonstrates that the production unit matches it. Transit performance can be validated separately against a published protocol (ISTA).

Two practical additions make the gate easier to operate. The first is a photographic record stored with the sample pack, so an inspector can compare appearance without unpacking the sealed reference. The second is a named contact on each side who can approve a deviation within a defined time, which prevents a batch sitting in a warehouse while an approval is sought.

Neither addition is expensive, and together they remove the two most common delays in the process: an inspector who cannot access the reference, and an approval that waits for a decision-maker in another time zone.

Finally, the sample gate works best when it is visible in the schedule. Putting the approval date in the programme plan, with the pilot batch scheduled after it, prevents the situation where production starts while the reference is still unsigned and a batch is subsequently rejected on appearance rather than on function.

That sequencing has a second benefit for regulated markets: the sample record supports the efficiency and compliance file (10 CFR Part 430 for US adapters and TUV Rheinland or another independent body for market-specific safety schemes), so the documentation trail from approval to shipment stays continuous.