Hi, can someone tell me why I getting a strange Cpk value? I know that that if you get a negative ( - ) cpk is because your mean is above or under spec's limit, but what I getting is -1.00000. Do I nee to adjust the setting on Datapage...help......
Those are my actual settings. My concern is why is a large number (Cpk -1.000000.000 ) that is telling me that the process is so out of control that need to be bring back to spec?
Here is an example : Bore Dia Spec: 17.7 / 17.9 mm. Min found 17.37 / Max found 17.79mm. As you can see there is a lot of variation. Also Matthew, I noticed that when I run the report on Dataspage and asked for CPK the LSL and USL are the same 17.9mm AThis might be part of the problem? since LSL and USL are needed to calculate the CPK.....
Yes...that was my error, assign a negative value to a negative tolerance......there is anyway to fix the data, I don't want to measure them all again.... I got 72 samples...and rgth now I'm in the middle, like sample # 39 or so...please help, at this point I will edit the program, so I know form sample # ?? on is OK...
Well I fixed the error, ran the program and Datapage still calculating an -1.000000.000 Cpk value. I wonder if the concentricity dim is influencing my output, since is an uniateral spec. 0.05mm Max.....
Here is an example : Bore Dia Spec: 17.7 / 17.9 mm. Min found 17.37 / Max found 17.79mm. As you can see there is a lot of variation.
Thanks for the quick response. Yes, I'm sure that is wrong, what I did was I use Minitab, it came back with a very different Cpk valuer.....
Cpk is defined as the lower value of either CPU or CPL. If your average is lower than your lower spec limit of 17.70 then it is mathematically impossible to get a positive value. ((17.79+17.37)/2)=17.58
I recently switched over to DataPage+ v4.1 and we are having an issue with tolerance. The program was written with the tolerances both positive, as it should be but they are coming into DataPage that way too. I could have sworn that there was a check box or something that made the negative tolerance negative but I can't find it. Can anyone help me?
Thanks Matt, this worked fine with the old DataPage, maybe it is something in the new. Been on the phone with tech support for three days and this is the last issue that I have to fix.
I changed the setting and ran another part. It didn't update the tolerances, I changed one of them to negative manually before hand. It didn't change that one back. Is there a check box somwhere to force it to update the noms/tols on execution that may have gotten turned off, in either program?
