They end up in product destruction. (e.g. unstitching a jacket to check the lining fabric). For these situations only, the inspector can choose a "special level".
So we have three "general" inspection levels, and four "special levels". For a given order quantity, each level gives a different number of samples to check. Let's see how it plays out in two examples.
Example 1: You order 40,000 products
The number of samples to draw from varies from 8 to 800. Depending on the level you choose, the inspection might take only one day, or up to 4 or 5 days.
Example 2: You order 3,000 products
The number of samples to draw from varies from 5 to 200. If the product is not particularly complex, a professional inspector can check 200 samples in a day. In this case you can choose the tightened level for more reliability at no extra cost. But the factory might have a little more repackaging work.
In practice, how to know the number of samples to select for each order quantity and each level? In the next article I will show how to read the statistical tables and get this information.
The AQL (Acceptance Quality Limit)
Another basic concept rings familiar to many importers, but is often not clearly understood: the AQL (Acceptance Quality Limit).
There is no such thing as zero defect
First, as a buyer, you have to know what proportion of defects is tolerated on your market. If you are in the aviation business, any defective part might cause a disaster, so your tolerance will be very, very low. But you will have to accept a higher percentage of defects if you source consumer products made by hand in China.
An objective limit is necessary
So, how many defects are too many? It is up to you, as a buyer, to make this decision. There are two reasons why you should not leave this to the inspector's judgment:
1. When it comes to giving instructions to an inspector, you should never leave gray areas-as they might open the door to corruption.
2. Your supplier should have clear criteria for acceptability, or they will see rejections as unfair. The AQL is the proportion of defects allowed by the buyer. It should be communicated to the supplier in advance.
The three categories of defects
Some defects are much worse than others. Three categories are typically distinguished:
- Critical defects might harm a user or cause a whole shipment to be blocked by the customs.
- Major defects are not accepted by most consumers, who decide not to buy the product.
- Minor defects also represent a departure from specifications, but most consumers would still buy the product.
For most consumer products, the critical defects are not allowed, and the AQL for major defects and minor defects are 2.5% and 4.0% respectively. Remark: a professional inspector will notice defects and evaluate their category by himself. But it is better if the buyer himself describes the most frequent defects and their categories.
How to read the AQL tables
The master tables included in the relevant standards are commonly called AQL tables. Let's take an example.
You buy 8,000 widgets from a factory, and you choose the normal inspection level. In the table below, you see that the corresponding letter is L.
Now let's turn to the next table. (It is only appropriate for normal-level inspections). The letter L gives you the number of samples to draw at random: 200 pcs. And what about the AQL? Let's say you follow the usual practice of tolerating 0% of critical defects, 2.5% of major defects, and 4.0% of minor defects. The maximum acceptable number of defects is 7 major and 10 minor. In other words, the inspection is failed if you find at least 1 critical defect and/or at least 8 major defects and/or at least 11 minor defects
Additional notes, for accuracy
- The number of defects is not the only cause for acceptance of refusal. The products can be refused because they are not conform to the buyer's specifications, even though their workmanship is very good.
- If you have two different products (made with different processes or in different factories), you should do two separate inspections. If you inspect them together, one product might be accepted even though it presents too many defects. Why? Because the better workmanship of the other product might "compensate" for its poor quality.
Now you know how many samples should be selected, and how many defects can be tolerated. But when should inspections take place? After production is finished? Won't it be too late for corrections if quality problems are discovered? These topics will be covered in the next article.
When to Inspect
The first two articles of these series focused on the different inspection levels and on the AQL tables. So you know how to set the number of samples to check and how many defects have to be accepted. With these settings and your detailed product specifications, a QC inspector can check your products and reach a conclusion (passed or failed).
But importers face one more question: when should the products be inspected? This is an extremely important issue for buyers willing to secure their supply chain. Spending a few hundreds of dollars to check and fix issues early can be an excellent investment; if might save you weeks of delay, shipments by air, and/or lower quality products that you have to accept and deliver to your own customers.
Four types of inspections
Let's picture the simplified model where one factory turns raw materials into finished products. (If you also have to manage the quality of sub-suppliers' products, the same model can be applied to them).
Pre-production inspection
This type of inspection is necessary if you want to check the raw materials or components that will be used in production. Buying cheaper materials can increase a factory's margin considerably, so you should keep an eye on this risk. A pre-production inspection might also be a good idea if you suspect that technicians on the factory floor have not been given all the information or have not understood all your requirements. How to make sure of this? By sending an inspector when the very first products are in process (under bulk production conditions). If you need to help the factory improve its processes, this is also the right time. But you will need to either send your own technicians, or find a highly specialized QC/engineering firm.
During production inspection
How to get a good idea of the average product quality, and be able to ask for corrections if problems are found? Send an inspector during production! It can take place as soon as the first finished products get off the line, but these samples might not be representative of the whole order. So usually such an inspection is done after 10-30% of the products are finished. What are the main benefits of an inspection at this stage?
- Be aware of quality issues early, and implement corrective actions before it is too late
- Communicate with your supplier about what is acceptable and what is not
- Get a precise production schedule
Final (pre-shipment) inspection
Inspecting the goods after they are made and packed is the standard QC solution of most importers. The inspector can really check every detail, including counting the total quantity and confirming the packaging. Final inspections are usually performed in a hurry, just before shipment. To avoid creating delays, inspectors can usually start after 80%+ of the order quantity is packed. Final inspections are appropriate if the factory delivered good quality on the exact same product in the past. Otherwise, buyers are strongly advised to have the products checked earlier.
The downside of final inspections is that inspectors adopt a "policeman attitude". Factories hate the risk of last-minute rejection, after all the goods are made (and might not be repairable). Buyers have the upper hand and can often ask for discounts and threaten to refuse the goods. This is a major cause for the corruption of QC inspectors. Most Chinese manufacturers are not organized to keep their processes under control, and they often discover the issues after an inspector shows them defective samples. Helping them with pre-production or during-production inspections usually makes more sense.
Container-loading supervision
In some cases, a buyer wants to make sure the factory ships the right products, in the right quantity, and with the right loading plan. This supervision can take place immediately after a final inspection (in which case the same inspector does the job). But usually it is a separate service that consists of two steps:
- Counting the whole quantity, opening a few cartons and doing a quick check on the products, and checking all the packaging details
- Supervising the loading of the cartons in the container or the truck
The importance of detailed specifications
1. Most quality issues come from miscommunication and misunderstanding. Importers should keep track of all their requirements regarding the product and its packaging. When a good deal of customization is involved, and for large orders, these specifications should be translated in Chinese (for the factory technicians) and included in a contract. When the time comes for product checking, the inspector will use this information as a checklist
2. After an inspection fails, the supplier usually agrees to repair the problems and support the cost of the re-inspection. Detailed specifications are useful in avoiding endless negotiations with your supplier
Putting It All Together
After introducing the inspection levels, the AQL, and the types of QC inspections, I am going to put it all together by walking you through several examples.
Example 1: 5,000 widgets from a new supplier
You have no information about the factory, so you should adopt the normal level (a.k.a. level II). The order quantity is comprised between 3,201 and 10,000pcs. If you open the first AQL table, you see the code letter is L. (If you forgot how to read the tables, see the article about AQL tables). And with the second AQL table you see that 200 samples have to be checked by the inspector. If you opt for the standard AQL limits (0 C. / 2.5% M. / 4.0% m.), the inspection is failed if at least one of these conditions comes true:
- One or more critical defects are found
- Eight or more major defects are found
- Eleven or more minor defects are found
And let's say you want the inspector to check all the product functions on a few samples. This test takes some time. You can choose special level S-2. You see this test will be done on 8 samples (by opening again the first AQL table and then the second AQL table). The 200 samples can be checked by one person in one day, so a third-party QC firm would quote you one man-day.
When to inspect? If this is a standard product and you have flexibility with timing, a final (pre-shipment) inspection should be enough.
Example 2: 30,000 watches from unknown supplier(s)
You suspect that your supplier gave orders to several workshops to produce your goods, but he won't tell you. And these items are rather valuable. A level-III inspection is probably the most appropriate.
If we read the AQL tables as we did above, we have to inspect 500 samples, and the maximum number of defects is: 0 critical, 18 major, 18 minor.
If a visual check on all samples and a function/accuracy check on a few pieces is enough, it probably takes two or three man-days.
When to inspect? If the supplier refuses to disclose the factory information, you have to go for a final (pre-shipment) inspection.
Example 3: Four different styles of garments from a good factory
You know that this factory's workmanship is quite good. But you want an inspector to check all the conformity elements, and in particular the measurements. Level I should be enough. You sell these products in boutiques at a high price, so you can only accept 1.5% major defects and 4.0% minor defects (for garments, there are generally no critical defects). The fitting is quite important, especially for the brassiere and the brief, so 3 to 5 samples should be measured in each size. There are 4 different types of products, so there has to be 4 inspections:
The total number of samples to check is only 127 pieces. But this order cannot be checked in one man-day, for two reasons:
- There are four different inspections to carry out. For each product, the inspector has to check all the conformity elements (fabrics, colors, accessories, stitchings...). And there are four reports to prepare.
There are 63 samples to measure, across four different products and many sizes.
So it will probably take 2 inspectors for one day, and maybe 3 (depending on the products complexity).
When to inspect? The best is clearly during production, when the products are on the line. As the 4 products might not all be processed at exactly the same time, it might be preferable to send an inspector at different times. And if an inspection is failed, a re-inspection can probably be performed at the supplier's charge.
The China Sourcing Blog is THE BEIJING AXIS online media platform to track the latest trends on sourcing and the Chinese economy. Taking on a multi-faceted, dynamic subject and carefully scanning everything from the mainstream media to the distant corners of the Internet, CSB strives to get to the bottom of all the best bits and pieces on China sourcing.Readers have left 2 comments.
1. Presidenttom Martucci, UnregisteredI have been importing from Asia since 1984 and I think this was an excellent article that should be a must read to anyone who is and who may be thing of importing.
I hope you do not mind if I reblog this on my blog later this month
2. Re: PresidentSmart China Sourcing Administrat, Unregistered I have been importing from Asia since 1984 and I think this was an excellent article that should be a must read to anyone who is and who may be thing of importing.
I hope you do not mind if I reblog this on my blog later this month
— tom Martucci>> Please contact The China Sourcing Blog administrator to ask for permission to reblog this article in your blog.The China Sourcing Blog (http://www.chinasourcingblog.org/) is the owner of this article.
Thanks!
From Smart China Sourcing Administrator
China Product Quality 
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