Good afternoon.
I was trying to work in a control chart when I realized that more than the traditional chart i need to do is short runs, because we changes styles (of the product) several times a day.however, I do not know how many samples of each style i need to collect to plot the chart, or how often I should collect them.
I think that the how often question is answered by the cpk value but I'm not sure.
I have several production lines and they can make all the styles. For example I can have product A coming from line 1 today, and two days later I can produce it in line 2.
Could somebody help me a little bit?

These are my questions:
-How many styles can I plot in a short run?
-How many samples should I collect?
-How often should I collect them?
-Is it true that according to the Cpk value i can determine how often i should take the measurements?
Thanks!!!

Any Control Chart experts here who can help out with this one?

With Circumstances like yours, I would still consider the normal control charts. Simply start using that chart each time you begin the run. If they enter all data into the chart from all days and all lines, and include certain "search" criteria with the entry, you have increased capabilities to review the information. My software will let me look at snapshots in time (like one run at a time) if I need to certify a lot. Otherwise, seeing all runs globally is critical for me. I have set mine up with search criteria like the line it is running on, the date, the operator, the job number, and any other conditions that might contain its own trend.

My explanations is as clear as I would like it to be, but previous experience would lead me to choose the standard method with added "search" criteria. It is usually less complicated to separate them by the standard criteria when you need it than trying to combine them afther the numbers are already crunched. I keep my groups open forever so we can always add to them, even if we don't run the part for a year or two.

How short are your short runs? 20 pcs, 200 pcs, 2000 pcs????

It would be real handy to know what kind of processes you are dealing with. In most cases it would be advisable to have a separate chart per line.