As an employee of a power company, am very 'sensitive' to control of procurement process. Build to print is not a big issue, but component procurement has always been a concern. Have just returned from some of employer's Asia factories where a considerable amount of time was spent going through supply bins.
While at the Shenzhen site, observed a CAB's factory audit. What a load of doo-doo. The only time the auditors do anything in an Asian country (other than Japan) is when the agency wants to bring in more revenue - which results in some rather creative variation notices. But the TJ, Mexico factory, where most of the custom stuff is done, is less problematic because: 1. They are next door to engineering. 2. The culture supports a different set of ethics. 3. Agency FUS audits tend to be more legitimate. Moral of the story -> know your suppliers and be aware of the culture of both the engineering group and the production sites. If your parts change structure or behavior - contact the engineering group first, because the factory has little control and even less interest in fixing the customer's problem. The designers care - it is their reputation and their baby. Brian -----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of McInturff, Gary Sent: Wednesday, October 31, 2012 7:47 AM To: 'John Woodgate'; '[email protected]' Subject: RE: [PSES] Possible Counterfeit EMC Components? Morning Ed, John has it correct. A company that produces thousands or even hundreds of thousands generally scales up its builds and inventory of parts as the design matures, but nothing can go to production release unless the company is sure that the design meets its goals. You wouldn't want to have order 10,000 input line filters only to find out that the compliance test identified a problem with that part and it needed a change. The logistics of returning and purchasing the correct parts is quite expensive. Obviously the design team tries to verify as much as early as possible, but it can't (or certainly shouldn't) go full blown production until after Engineering design verification is complete. There should be no known issues on a design when its thrown over the wall to mass production - and manufacturing shouldn't accept it until they are convinced that the design is complete. As I read it - the designer did exactly what he should have done, his manufacturing arm doesn't! seem tied into his quality or design process or Design change request process and changed his design to reduce cost with no regard to performance. This happens a lot with off shore suppliers that aren't poorly monitored. I had a SMPS from a very large vendor that for the first two years we used the supply performed well. It had been used in several designs and had gone through a series of compliance tests successful. A new end product design which also used the power supply was going through final tests and the supply failed an immunity test. Since the supply had been used and verified in many other designs I assume a bad unit. After swapping it out a couple of more times it was obvious that something had changed. When I called the supplier to inquire I got "Oh you wanted one of those supplies". They had made some cost reductions without telling the customer base and they knew the supply no longer met the requirements but shipped it without changing the part number etc. T! here was no way that our purchasing department could tell anything was different. The vendor knew it but not his customers, and we certainly weren't the only customer of this "off the shelf" supply. The cost of purging inventory and the line shutdown while correct power supplies were shipped was very expensive for us. It might be noted that the vendor saved themselves lots of money, but they certainly didn't pass on the cost savings nor did they reimburse us for the cost of the inventory purge and lots production time. Some countries are almost famous for making cost reductions without verifying them. I think someone earlier pointed out that their supplier thought they could cut the cost of a motherboard if they took off all of those pesky "bypass" caps etc. As a military guy you likely familiar with MIL-TFP-41 (Make it like the F*&#$ print for once!) Sometimes you don't get what you pay for. To amplify Johns comments just a bit, one should do production audits but that can be prohibitively costly to do effectively when lots of product lines are involved. Gary -----Original Message----- From: John Woodgate [mailto:[email protected]] Sent: Wednesday, October 31, 2012 3:55 AM To: [email protected] Subject: Re: [PSES] Possible Counterfeit EMC Components? In message <[email protected]>, dated Wed, 31 Oct 2012, Ed Price <[email protected]> writes: >I thought that compliance testing was supposed to be done on the >"as-shipped" product, not the designer's prototype. Neither: the prototype is not representative and 'as shipped' is too late. Maybe the 'pre-production' phase has been eliminated from modern manufacturing, but it used to produce 5 to 10 sample products using the purchased parts and built under as close to production conditions as possible. In those days, some moulded parts might be replaced by fabricated parts, but with 3D printing.... These samples not only increase confidence in the design, and eliminate bugs, but can be used for compliance testing. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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