Conflict between department of MSA and Capability Study

[Black arrow]

Hello,

We are having lot of discussions concerning MSA studies and Capability studies at my work. We see a conflict between those two topics. The department who is working with MSA see advantages with process variation which are wide ( when analysing % study var & ndc ) and the people who is working with cap.studies prefer narrow process variation.

This is quite enoying and sometimes i think that this is common situation for companies who is working with MSA and Capability studies?

OR do we take wrong approach when it comes to select parts for MSA studies of % Study var & ndc?

 

[Bev D]

Re: Conflict between department of MSA and Capability Sstudy

You are actually thinking of it incorrectly.

the process variation is what the process variation is.
A process that has good capability WILL have process variation that is smaller than the tolerance width.
A good measurement system will have low measurment error in relation to the process variation. IF your MSA samples are not representative if the process variation - which occurs frequently as many peopel don't take a random representative sample - THEN your NDC will be poor because the spread of hte parts you took was too narrow (not representative of the true process variation) AND your % tolerance can be acceptable because the variaiton of the parts is not taken into account in this calculation.


There is no recomendation of a wider process variation (than that which actually exists) to get a better NDC - that is manipulating the study...