Cmk is defined as a Capability Index for a Stable Machine

[SteveT]

Could someone please describe to me what statistical index Cmk is, what it means, and how to calculate it.

Many Thanks SteveT

 

[freeda]

Cmk is defined as a capability index for a stable machine. It uses the same formula as Ppk.
Cmk is a short term study of a machine capability. Whereas Ppk is a short run study for a process.

 

[Don Winton]

See Also:

Cmk calculation
Spc from each cavity?
Ppk vs. Cpk
Ppk
Cm vs. Cmk ?
The difference between the R&R study and the Cmk
CPK vs.CMK

Regards,

Don

 

[Al Dyer]

Thanks for the link Don, it's a good read.

ASD...

 

[Don Winton]

I do not know about Cmk, but Cpmk is defined as:

Cpmk = (USL – LSL)/(6*(sqrt(StandardDeviation^2+(mean – T)^2)))​

Where T = Target Value.

This link http://www.asq.org/pub/jqt/past/vol32_issue4/qtec-440.pdf gives some additional info. This is a PDF file, so you will need Acrobat Reader to access it.

Hope this helps.

Regards,

Don

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I was better but I got over it.

 

[Don Winton]

...what it means...

Ooops. Forgot. Cpmk is used when the tolerances are not symmetric about the target.

Regards,

Don

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I was better but I got over it.

 

[narfeldt]

Ain't Cmk=revised rates of machine capability and calculates by the formula:

Cmk = 2((UTL-Mean)/(Xmax-Xmin))
Cmk = 2((LTL-Mean)/(Xmax-Xmin))
Cmk = the lowest value of above formula

Is this incorrect?

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/Best wish Narfeldt

[This message has been edited by narfeldt (edited 07 June 2001).]

 

[Marc]

Blast from the Past!

 

[bobdoering]

Bothe's book Measuring Process Capability: Techniques and Calculations for Quality and Manufacturing Engineers has a myriad of capability indices for all occasions. Poor guy, all that work to seek the holy grail of one number to descibe a process.

By the way...CM Punk is a WWE wrestler...just in case you get on the wrong Wiki page looking this up.