2022 Volume 7 Issue 3 Pages 161-172
When a process demonstrates complex cause-and-effect relationships, process adjustments are often used, such as automatic process control (APC). On the other hand, a statistical process control (SPC) is used to identify the causes of abnormality. For example, we use control charts for process monitoring. However, in a process with process adjustments, careful consideration should be taken toward choosing control characteristics as abnormalities may go undetected through the sole monitoring of output.
In many cases, the complexity of the gear grinding process complicates the identification of abnormal causes. Therefore, we indicate a decreased deviation from a fixed target value by using feedback adjustments.
There are correlations among multivariate quality characteristics in cases where feedback adjustments are not used. However, in the process with feedback adjustments, the relationships are disappeared as a result of the controlled quality characteristics. In such a process, we cannot detect changes in the relationship by monitoring quality characteristics, and therefore, we allow abnormalities to continue in the process.
This research shows whether feedback adjustment is effective for the process and then shows appropriate control characteristics, other than quality characteristics, for the use of T2-Q control charts to monitor the relationships among variables using the case study of the gear grinding process.