What does m stand for in Cpm?

G

Gagandeep S. Datta

Hi,

As per one literature m = no. of subgroups; but, as per AIAG manual m = subgroup size.

What exacty is m in Cpm?
 
See the Elsmar Wiki: The Cpm index indicates how well the system can produce within specifications. Its calculation is similar to Cp, except that sigma is calculated using the target value instead of the mean. The larger the Cpm, the more likely the process will produce output that meets specifications and the target value.

/Claes
 
D

Darius

What exacty is m in Cpm?

There is ... , like Wikipedia put in some topics a disinbiguation case:

I see 2 SPC Cpm definitions, one is like Claes ones:

Cpm Calculus

A possibility is "variation from the mean", as can see in:
A journal preview for Cpm index

From the abstract:
... takes into account the location of the process mean between the two specification limits, the target value and the process variation ....

Another tread about Cpm, but called "Taguchi process capability"

The other is a capability index calculated as allways but for a machine at startup (to know the machine's capability at a new instalation), so in this case could be "m = machine".

A good text about machine capability
 
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