Re: Estimating Part Number Capacity

[GrantBlair@aol.com]

In a message dated 5/8/2000 12:34:52 PM Eastern Daylight Time, 
TQNELSON@aol.com writes:

<< I must be missing something. Did not WED teach, "This simple illustration 
 should put to rest forever use of measures of dispersion like Cpk, as it has 
 no meaning in terms of loss. Moreover it can be decreased to any value 
merely 
 by widening the specifications." (TNE, p. 226) >>

In many cases, widening the specifications may be entirely appropriate.
Often,  customer requirements are set from pilot plant or production runs by 
someone asking "What was the range of the data?" This becomes the 
specification with no attempt to understand the customer's requirements, or 
learn about the process.
An example of this from experience was a company's procedure which set 
specifications by determining the sigma, and multiplying it by +/-4.
This company benefited from applying process capability (Cpk) principles.
Once they realized they would always have a Cpk of 1.33, it forced them to 
understand the customer's  requirements.

Grantblair@aol.com
Ninety Six, SC 
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