How does a random quality inspection work?

On the last trade show I attended, I noticed that I explained over and over again how we perform random quality inspections. There must be a better way to pass this message.

A graphic designer helped me render it visually, and here is the result:

To go further:

• lots of great information about inspections on this page.
• Understanding what  “AQL” (Acceptance Quality Limit) means in simple terms here.

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TRANSCRIPT:

FINAL RANDOM INSPECTIONS – How is quality controlled before shipment?

Most consumer goods exported from low-cost Asia to Europe and the USA are inspected randomly. For example, for an order of 8,000 pieces, only 200 samples are selected for inspection. How can an inspector draw valid conclusions after checking some pieces at random?

Here is how it works.

1. COMMUNICATION OF REQUIREMENTS

The purchaser describes his product: specifications, dimensions, labeling, packaging… The more precise the information, the more you take advantage of the inspection. If possible, an approved sample can be sent for the inspector’s reference.

2. AN INSPECTOR GOES TO THE FACTORY

When? After all production is finished and packed, and about 2 days before the goods leave the factory.

(In most cases, one inspector is enough)

3. QUANTITY VERIFICATION

The cartons are counted, to check if the whole quantity is presented. Then the inspector randomly selects a few cartons, opens them, and checks their content.

4. RANDOM SELECTION OF SAMPLES

Some samples are taken from each of these cartons, totally randomly. The inspector follows industry-standard statistical rules to ensure his findings are valid.

5. COSMETIC AND WORKMANSHIP CHECK

These samples are checked thoroughly for visual defects. A defect is an imperfection on the product (or its packaging). The statistical rules provide a maximum number for each type of defect. If there are too many defects, the inspection is failed.

6. CONFORMITY VERIFICATION

The inspector also checks if the goods presented by the factory correspond to the purchaser’s requirements. For example, the products might be too small, in the wrong color, incorrectly labeled, or insufficiently protected.

7. TESTING IN THE FACTORY

The inspector performs some tests that are specific to the product, with the factory’s equipment. Tests vary according to the nature of the products. A few examples: checking if there is current leakage on an electrical device; checking if a piece of furniture falls over easily; checking if the export carton is strong enough.

8. REPORT PREPARATION

The inspector issues a report that describes the situation and illustrates it with photos. It documents his findings about presented quantity, visual defects, conformity to requirements, and on-site tests.

“Here is my report. You have the info you need to take a decision(accept or refuse the shipment).”