Cp & Cpk question...
Cp & Cpk question...
(OP)
Where does the value 1.33 come from when calculating Cp and Cpk ?
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Cp & Cpk question...
Of course it also assumes that your spec limits are meaningful. I remember that when we specified Cpk=1.67 for a new process the manufacturer immediately asked us to widen the specs. Idiots.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Cp & Cpk question...
Thanx
RE: Cp & Cpk question...
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Cp & Cpk question...
So are you are saying
Cpk= abs value of (process mean-speclimit)/3sigma
If so, aren't there well defined processes where the speclimit can be stated with confidence?
Just asking.
RE: Cp & Cpk question...
Upper Limit
Cpk = [U.L - process mean]/3std
Lower Limit
Cpk = [Process mean - L.L]/3std
Cpk = min of Upper or Lower
Maybe that helps.
RE: Cp & Cpk question...
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Cp & Cpk question...