When I go to factories I like to observe quality inspectors from buying offices or other QC agencies. Sometimes I see an inspector come in, ask the factory for a certain number of pieces, and get to “work” right away. By “work” I mean checking products.
While he may feel quite productive, he is seriously cutting corners! Here are the main issues I have with this approach.
- Not doing a random pick — it means the factory can select the best products and “adjust” them if necessary.
- Not looking at all cartons — what if some of them are wet, damaged, in different sizes…?
This inspector’s report might look great and be full of photos, but to me it is close to worthless. He hasn’t done a random inspection… he hasn’t tried to estimate the average level… he might actually have done an inspection of the best products!
In short, he skipped the all-important phase of sampling, which ensures randomly-selected products (as representative as possible of the whole batch) are inspected. He might not see issues that are present on 40% of the goods, for example, and declare that defects are below the AQL limits.
Companies that use our software for QC inspections have access to a lot of historical data. They are often surprised by the time their inspectors spend in the “counting and sampling” phase and they sometimes wonder how to cut that time.
Well yes, it does take time. Sometimes 20 minutes, but that’s rare unless the inspector goes to that factory very often and things are all lined up nicely. Often it takes 30 to 90 minutes. When there are many SKUs, the products are spread around the factory, and the staff needs to search for them, it can take half a day!
Let’s break it down. Why does it take so long?
Finding and counting
First, the products might be in different stages of preparation — and different places:
- Some packed
- Some unpacked, waiting in the packing department
- Some unfinished, somewhere in production workshops
The inspector should try to count the products quickly, or at least to estimate (roughly) the quantity.
Then the inspector needs to do a picking. If we just say “give me 4 cartons from each pile”, the factory staff will naturally pick them from the top of the piles. I would do the same if I were in their shoes. However, an inspector needs to get cartons from each part of the pile.
Let’s say it frankly: many times this doesn’t happen for the simple reason that the factory refuses that extra work and the inspector doesn’t want to create a conflict that early in his job. If that’s important to you (and it should be), I suggest you do this:
- Get a confirmation from the supplier about it;
- Request the inspector to take photos/videos of cartons being picked from the bottom and the center of carton piles.
Why is this so important? A malevolent factory manager might have placed all the defective pieces at the bottom of the piles. And, from my observations, this tactic will work with most inspectors.
After the picking, the inspector has to supervise the transportation of those carefully picked samples to the place of inspection (often located away from the packing department… don’t ask me why).
A common frustration is having to wait for the lift to be available. It takes sometimes 30 min if there is an urgent shipment out or delivery in!
(If the inspector goes back to the inspector room, the factory staff might open the selected cartons and replace their contents with high-quality samples… Not a risk worth taking.)
Obviously it makes sense to start checking the outer cartons during that time, but that has to be done in poor conditions. If the inspector works on a mobile app, he has easy access to specifications. If he needs to get his laptop for that, no luck…
In the inspection room
There might be many people in the inspection room, talking and calling the inspector’s attention. Not great for productivity. Or, worse, there might be nobody to help unpack the goods!
And then, once the selected cartons are in the inspection room, the sampling job is not finished. Here is an example:
- 125 pcs to pick from 12 cartons
- 1 carton contains 20 pcs
- 9-10 pcs are to be picked from each carton
The inspector should ensure the samples are picked from the top and the bottom of the cartons.
Again, a savvy manufacturer might have placed all the defective pieces at the bottom of cartons. Maybe I am paranoid, but I am sure it happens from time to time. It is such an obvious loophole, there is no excuse for not preventing it.
Most inspectors are in a hurry to get to “real work”, sit down, and ask the factory staff for help unpacking the goods. From a distance, they don’t keep an eye on the factory’s picking process. Only the samples from the top get picked. Mistake.
Double sampling work (in some cases)
If less than 80% (or whatever was required) was ready & packed when the inspector arrived, the factory often finishes packing later in the day. They often ask the inspector to do a second sampling.
Here is an example:
- Total quantity: 10,000 pcs
- Requirement: 80% packed
- Quantity packed when inspector arrives: 6,000 pcs (60%, not 80%, of the total)
- At that time, inspector picks samples from those 60% only and starts his inspection
- 3 hours later, all remaining 4,000 pcs are also packed, and they are not mixed with the first 60%
- Inspector picks more samples (so that in total he gets to the number he needed to check) from the 40%
- The report mentions that 100% was packed
In theory it should not happen, but it is often tolerated. When one thinks about it, it does make some sense.
Rather than rushing to finish the job, it is better if packing operators focus on doing a good job (and creating fewer quality issues). Obviously, the cartons that were part of the first sampling should be placed aside and not included again. (This requires a quick check too.)
Some clients have asked us to skip the sampling stage with some of their suppliers. In practice, a certain number of samples are ready for our inspection when we arrive. We don’t waste time picking cartons and so on.
It can makes sense if they have worked with the same manufacturer for years and there is no question about unethical behavior. At one point, when the inspection budget gets tighter, something has to give. It might make sense to save time here rather than skipping some lots. That’s a business decision and I respect it.
In 98% of cases, though, the sampling phase should be given sufficient time and attention. It is really, really important.