Rodel, I haven't seen many responses to your posting.  Let me submit my
comments from a quality statistics perspective.

If you have not done so already, you can find formulae and mathematical
rationales in any quality statistics or SPC book.  Douglas Montgomery has
written a good one that I'm familiar with.  Charles Quesenberry's SPC
Methods for Quality Improvement is another.  If you look at www.asq.org
(the American Society for Quality) you can see what its bookstore has.  The
people at ASQ are helpful if you call them to inquire about their
literature.

The process needs to be in control to calculate a Cpk.  Also, the most
prominent formulae in books are based on the assumption that data are taken
from a normal distribution.  If data do not reasonably fit a normal
distribution, things get more complicated.  The popular statistical
software packages will do the calcualtions to get a Cpk for such data using
other distributions.

While high Cpk is desirable, I would be cautious about making quantitative
inferences when Cpk gets above 1.5 or so (if you are fortunate enough to
have any that high).

Lou Hart

-----Original Message-----
From:   Rodel Herman [SMTP:[log in to unmask]]
Sent:   Saturday, May 19, 2001 3:39 AM
To:     [log in to unmask]
Subject:        [TN] Cpk study

Hi Technets!!!

Can  anybody help me in finding the most proper / standard way of
getting equipment capability ( Cpk). At this moment , I'm working on this
especially on Pick and place , and dispensing machines.

Anybody's information is highly appreciated.

Best regards ,

Rodel R. Herman
Philips Semiconductors Phils. Inc.
E-mail : [log in to unmask]

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