Introduction to Three most Common types of Quality Inspections (2024)

The term “inspection” generally refers to the activity of checking products. The quality inspector usually follows a pre-established checklist that is based on the product specifications.Inspected products can be the components used for production, semi-finished goods, or (most often) finished goods before shipment to a customer.

Checking quality only at the end of production is very risky. But you don’t have to wait until everything is done… As you can see below.

The three most common types of quality inspections

There are mainly three tools at the disposal of buyers, to check on the quality of their suppliers’ products. Each buyer should try to choose the solution(s) that best fit(s) her needs.

Pre-Production Inspection

“Garbage in, garbage out”: a factory usually cannot turn defective inputs (components, or raw materials) into good products. And the problems are much harder to detect once the materials are embedded in the final product.

Thus, to decrease quality risks,the inputs can be inspected prior to production. Some samples can be taken randomly and checked visually (or sent to a laboratory for tests). Also, the buyer should clearly define what inputs are acceptable, before he gives any order.

An experienced inspector can alsoexamine the making of a prototype/sample, to make sure of two things:

·Has the factory understood the technical files?

·Has the development team clearly communicated the requirements to the manufacturing team? Is the equipment for mass production similar to that used for making prototypes?

Usually,production has already startedwhen a pre-production inspection takes place. It allows the inspector to examine the process, and sometimes to check a few finished products. However, in this case, the factory might refuse to stop production (to avoid disruption of the lines), even though the inputs are not conforming or the process is not satisfactory.

Generally speaking, pre-production inspections are adapted to customized and complex products. More standard items should be inspected during production (see below).

During Production Inspection

Should a buyer wait until the end of production, before doing an inspection? In case products are defective, the following problems might arise:

·The factory has to rework (loss of time).

·If the products cannot be repaired, the factory should re-order components, and re-produce (which means long delays, and a financial loss for the factory).

·The supplier might refuse to repair or re-produce, particularly if the previously-agreed specifications are ambiguous.

Typically, in an in-line inspection, the first products that got out of the line are inspected for conformity. If issues are raised at this stage,the factory can immediately take some corrective actions and avoid delays.

Also, based on the production start date and the number of products already finished,the buyer can have a fair idea about the shipment schedule.

A third advantage of in-line inspections is that the buyer knows where the goods are produced. Some suppliers show a factory to a buyer, and then sub-contract the production in another workshop (this happens every day in China).

In any case, in-process products are rarely checked. It takes a technician to reliably detect errors on unfinished products.

Final Random Inspection

This isthe most popular type of QC inspection for importers. It takes place once all the products are finished and ready for shipment.

Note:A “packed product” is ready for shipment (i.e. in a closed export carton with full shipping marks). In many cases, the inspector accepts up to 20% of unpacked products per reference. This way, the inspection can often take place without delaying the shipment.

The conformity of the products is checked against a list of criteria defined by the buyer (product quantity, workmanship, function, safety, aspect, size, packing…).

Buyers are advised to ask their inspectors to keep track of which cartons were opened. This way, a 2nd “spot” inspection can give an idea of how seriously the control was performed.

Of the three inspections presented in this article,this is the only one where the total quantity of products can be counted, and where samples of finished products can be drawn in a truly random manner–and thus be representative of the whole batch.

As a result, the results of final inspections are more reliable. And some buyers assume that the inspectors should “guarantee” the quality of the whole order quantity, when the inspection is passed. Unfortunately, it is impossible for several reasons:

·After the inspection is done, and before shipment, many things can happen. A dishonest factory can ship a smaller quantity, substitute the content of the cartons, etc. There is a solution to avoid this: a container-loading supervision.

·An inspection result (pass/fail) is not 100% reliable: even a random sample might be better than the average products; the inspector might make a mistake; an inspector might get bribed by the supplier, etc.