On 7/9/16 1:21 AM, Ian White wrote:
Several good points there, about the variability of ferrite cores.
Ferrites are, quite literally, "bakery products". Just like bread and
cakes, the properties of ferrites depend on the correct ingredients
measured out in precise quantities, on the precise manner in which those
ingredients are mixed, and also - most critically - on the
temperature/time profile of the baking and cooling.
Just like baking, the manufacture of ferrite materials is a complex
blend of science and know-how. Once a specific product has been
developed, consistency can only be achieved by repeating exactly the
same processes for every batch.
It is very easy to see how QC problems could appear from outsourcing
those critical processes to an offshore company that lacks the original
manufacturer's in-house know-how, with a language barrier that prevents
that information being accurately transferred.
It doesn't even have to be offshore. Not all ovens are the same either
in temperature profile or internal distribution, and there's a lot of
other aspects.
There's more than one instance of a company "losing the recipe" even in
the same plant, but also when moving manufacturing operations. When
Microsemi bought Symmetricom, they moved the Chip Scale Atomic Clock
(CSAC) manufacturing (entirely within US and carrying over some of the
same people), and lost the recipe somewhere, adversely affecting the
operating temperature range.
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