Process capability indices are widely used in industry to achieve and maintain a high-quality level of manufactured items. The successful application of process capability indices requires the process to be stationary. This is not the case for trended processes with regular adjustment, which are very common in manufacturing processes. An interesting and important question is how to define and interpret the process capability for such a process. In this paper, the traditional process capability indices are modified for these trended processes. Two different sources of process variation, one from the process trend, the other from random variation, are identified and used to develop new process capability indices. Based on these new indices, we show that the capability of trended processes can be improved through periodic adjustment to its maximum achievable value. We also develop the procedures to determine the adjustment frequency to meet any prespecified requirements on the capability index or on the process yield.
Process capability indices for a regularly adjusted process
Reprints and Corporate Permissions
Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?
To request a reprint or corporate permissions for this article, please click on the relevant link below:
Academic Permissions
Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?
Obtain permissions instantly via Rightslink by clicking on the button below:
If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.
Related research
People also read lists articles that other readers of this article have read.
Recommended articles lists articles that we recommend and is powered by our AI driven recommendation engine.
Cited by lists all citing articles based on Crossref citations.
Articles with the Crossref icon will open in a new tab.