If you're doing anything hardware related and are considering outsourcing to China, here are some important and useful tips that you should know, to save you from wasted time and costs in the process:
At a place I worked a few years ago we had to individually retest every single unit of our products. This involved opening up packaging and repacking and reshrinkwrapping afterwards. In between unpacking and repacking there was testing and finding about 1/3 of them always had problems. Some boards could be fixed by diagnosing to the component level, replacing components and even resoldering incorrectly wired interboard connects. This work was done by asian immigrants of uncertain immigration status. This rework quadrupled the cost of the products but somehow it was still cheaper than just manufacturing locally to begin with, something like the exact same product was costing $20 per unit from asia, but $200 per unit to build in the US. Apparently the big cost difference was due to the effect of environmental laws regarding not being able to dump toxic waste in a river in the US.
This is par for the course. I have friends who have had to manage manufacturing processes in China. You have to be very specific, to the point of utter paranoia, in the instructions that you provide. Wherever, and I mean absolutely wherever a corner can be cut, it will be cut at this level.
One friend had to get rubber household cleaning gloves made in China. He worked for a retailer and this would be for their store brand. If they specified something to be done, it would be done exactly the way they wanted. If something was unspecified, you could bet that the cheapest, shoddiest, most dangerous materials/processes would be used. For example, he never specified that the rubber used should actually be safe to be worn by humans. Prototypes came back with obscene levels of toxins in a glove that is meant to protect people from getting their hands dirty with household cleaning chemicals. There was just no common sense to fill in the blanks in the instructions here. Once they sorted out this issue, as another commenter mentioned, they would have to check each and every shipment because the manufacturer would try to sneak cheaper variants into the batches. Eventually my friend went and inspected the factory on a business trip only to find so many ethically questionable practices that he eventually decided to switch to another job.
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