Random Inspection for Quality vs Full Quality Inspection

Jan 22, 2023 Chapter 4. Inspection

Random inspection for quality is by far the most popular QC services. It is used for almost all consumer products purchased in Asia. The final inspection report is usually used by the importer to authorize shipment and trigger payment.



When Do you Need a Random Inspection?

As part of their quality control plan, importers should decide when the random inspections for quality should take place.

By default, most buyers use random quality checks to reduce the amount of work. And, in most cases, sellers follow ISO 2859-1 (or ANSI / ASQ Z1.4) to set the inspection level and the AQL limit.



Types of Random Inspections for Quality During Different Stages:


Choose Best Suppliers Catch Problems Early Verify Quality Before Shipment

Factory audit

Sample test

Pre-production inspection

During production inspection

Pre-shipment inspection

Container loading inspection

Suppliers selection 5% 30% 80% Shipment
% of Finished Production




Who Needs a Random Inspection Check?

If you work with multiple suppliers and your quality standards indicate 2-3% of secondary products, you may need to do the random inspection.


Finally, let me get one thing out of the way: not all products need to be checked.

  • If a manufacturer has great systems and processes, and if they have a history of complying with your quality standard, there is usually no reason to send quality company to their facility.
  • Similarly, if you can easily return the whole batch and it can be reworked quickly, you probably don’t want to spend resources on random inspection for quality whether they did as promised.



The Classic Random Inspection Process is As Follows:

  1. Quality inspector goes to the supplier’s factory.
  2. Calculate the number displayed and randomly select boxes and products
  3. Check the product and its packaging for visual defects.
  4. Confirm compliance with specifications
  5. Prepare a report that contains pass/fail results.




What is Check During Random Inspection for Quality?

Three types of problems can lead to inspection failure and possible rejection of shipment by the buyer.

1. Conformity to Specifications.

All relevant aspects of the product are controlled: quantity, components, assembly, aesthetics, function, dimensions, labeling, packaging, etc.

Ideally, the buyer has prepared a document listing all specifications for the product to be inspected, and these specifications will serve as a checklist for the inspector. When no such information is provided, the inspector simply collects the information for the buyer’s review.

2. Number of Cosmetic Defects.

According to the sampling plan, the inspector randomly selects a predetermined number of products. He inspects and counts the number of defects one by one and compares them with the AQL limits.

3. On-site Testing.

Specific tests are included in the inspector’s work depending on the product type. For example, product drop test with 3 samples from a concrete floor of 80cm height (test fails if at least 1 sample breaks or no longer works).



What is the Random Inspection Limit?


  • Suppliers Are Unhappy about This

Importers often put a lot of pressure on suppliers, who may face difficult price renegotiations (or even cancellation of orders) if the product has serious quality problems. QC inspectors are seen as the police and can be bribed if monitoring is not adequate

  • There is no 100% Guarantee

It is done on a randomly selected sample, not on the entire quantity. Even if so-called “normal” or “tightened” levels are followed, there is always a small chance that the findings will not apply to the entire shipment.

Likewise, a dishonest factory can short-order or switch products before shipping (unless the shipment is also monitored).

  • It is Too Late

If the buyer sends inspectors after production is complete, it may be too late. Either because the defective product must be reproduced or because the rework time is too long.

That’s why I usually recommend do random inspection for quality during production: problems will be detected early and some suppliers see them as help rather than supervision.



100% quality inspection in China



When Do You Need a 100% Quality Inspection?

From Supplyia experience, I would like to point out three reasons why some importers want to do piece by piece 100% quality inspection:

1 Return defective products fee is high – it’s worth spending more time and money cleaning up all the bad products. 

2 There is a strong suspicion that many products have quality problems and that the supplier’s quality control is not doing a good job.

3 After the inspection, it is possible to replace inferior products with quality ones. 



Is it More Expensive to Do Random Inspection vs 100% Quality Inspection?


Most people would say, “Yes, it’s more expensive.”

However, this is not always the case. We’ve had a lot of situations where the cost of full load is very similar.


Let’s give you an example:

1% of product defects and these defects have been documented and are not difficult to examine

The unit price of the product is $5

The fixed installation cost is approximately $100

The inspector can check 50items within 1 hour.

The operator is charged RMB100 per hour for all time the product is inspected. 

The cost of sending a professional QC to the factory is $299 per person per day.


To make a fair comparison, we estimate that importers will still need to pay for the defective goods after a random inspection. 


Cost comparison – random inspection vs 100% quality inspection

Random Inspection vs 100% Quality Inspection



Should 100% Quality Inspection be Finished in the Supplier’s Factory?


If the quantity is small and the product is simple, it can be done in the factory where the goods are manufactured.

However, if the work required five or more working days, the cost would increase significantly, which might not be realistic.

Deliver a batch of products to Supplyia warehouse to do 100% inspection by trained operators, and repacked immediately. It is more efficient and much cheaper than hiring people to do it in the factory. One of the great advantages here is speed and simplicity.




Practice Between in Full Inspection and Random inspection for Quality in China.




We recently started to adopt a different approach with the help of our clients to do the quality control in China:

  1. They start with piece by piece inspection in China (paid by the manufacturer)
  2. They see what defects come up most often
  3. They give advice to the manufacturer to decrease the most frequent defects
  4. If the proportion of defectives goes below a certain target, they switch to random inspections (paid by the importer)
  5. If the proportion of defectives goes back up, they switch back to full inspection/piece-by-piece inspection (paid by the manufacturer)


In the mid-to-long run, it decreases the costs for the importer by forcing the factory to solve the real issues. If you need random inspection for quality in China, you can try to contact us.




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