Akram

Control charts usualy use 3 instead of 4.

I am surprised that you guys are treatinting Darth so harshly. He, Mike Carmel, Vinny and Ken are the most helpful people on this forum. I am sure that if they stop participating to the forum, there will not be much left, they are the ones who keep it alive.
You need to know when someone is joking or not. Stats and Six Sigma are very dry,…[Read more]

There is no statistical relationship between the control limits and the spcification linits.
The specifications are set by the customer requirements while the control limits are determined by the process.
try this http://www.sixsigmafirst.com/controlcharts.htm

Try this
http://www.sixsigmafirst.com/controlcharts.htm

BG,
The types of control charts used to monitor quality depend on the nature of the data gathered. Monitoring the production of parts that just either good or bad is different than monitoring specific CTQ ( such as length, weight ) on a part. In other words, the type of control chart will depend on whether the data gathered are attribute,…[Read more]

The c-chart monitors the process variations due to the fluctuations of defects per item or group of items. The c-chart is useful for the process engineer to know not just how many items are not conforming but how many defects there are per item. Knowing how many defects there are on a given part produced on a line might in some cases be as…[Read more]

try this website. scroll down to the bottom of the page and you will have the answer to your question.
http://www.sixsigmafirst.com/sampling.htm
Akram-Al Qiram.

http://www.sixsigmafirst.com/controlcharts.htm