Hi I brought up the idea of a full spec at the time. Since we made the parts and used them it seemed like a reasonable idea. The price on the parts went from $ 0.0326 each to $ 18.56 when the major parameters were banded 2 to 1. Since we were using 4 in a $ 35 item (bom was about $6) the suggestion was not well received.
Bob On Aug 14, 2010, at 11:50 AM, Magnus Danielson <mag...@rubidium.dyndns.org> wrote: > On 08/14/2010 05:08 PM, J. Forster wrote: >> FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or >> instructions in a production design is a fool. >> >> If you are that silly, you must fully specify the selection criteria. > > Using non-spec aspects needs documentation, motivation and risc analysis. > > I've designed a selection routine for a component which still ticks on with > good statistics. The main problem is that eventually that component will be > on last buy level. Obviously it seems the selection was chosen on the > conservative side, so it works in shipped products regardless of batch. > Trimming of the manual routine has lowered a certain failure mode of testing. > > Any spec should be verified. Published specs needs verification with real > components. Unpublished specs needs consistency testing or even selection > testing on all components. Cost of testing needs to be understood and risc of > low yield in future needs to be understood and alternative approaches could > be put in place before running on flat tires. > > At times it may be cheaper and safer to run with more expensive components > which is within spec. > > Cheers, > Magnus > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
