[TowerTalk] 31 mix variability ... lost processes

[Charles Farr]

When dealing with potting compounds, glues, binders and such, often the 
providers, will make chemical changes, or mixes without informing the 
user. Talk about screwing up the mix since there is usually nothing that 
distinguishes the original product from the 'new' one. Same part number, 
etc.

Chuck, W6AJW



On 07/09/2016 12:09 PM, David Gilbert wrote:
>
> It doesn't even have to be the fault of the receiving entity, whether 
> that be a new location or new owners.  I worked in the semiconductor 
> industry for over 30 years and saw several examples of "lost recipes" 
> simply because the original process was never properly investigated, 
> characterized, and documented in the first place.  Processes that had 
> produced excellent product for years might suddenly shift because some 
> influence that had never been understood at all changed.
>
> We actually had one product that shifted dramatically for the worse 
> because a piece of equipment was upgraded to a cleaner version, and it 
> took a lot of engineering work to understand the favorable impact that 
> the carrier lifetime killing effect from the older, dirtier equipment 
> had on the product.
>
> I think most people would be appalled to learn how poorly many 
> manufacturing processes are characterized in many industries, but it's 
> probably understandable given the extreme difficulty of defining all 
> possible influences in the first place, and then rigorously testing 
> (or even modeling) all possible interactions of them.
>
> 73,
> Dave AB7E
>
>
>
> On 7/9/2016 7:41 AM, jimlux wrote:
>> 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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