NEW APPROACH FOR MEASUREMENT OF THE EFFICIENCY OF Cpm AND Cpmk CONTROL CHARTS

Process capability analysis is a very effective way for improving process quality by relating process variation to customer requirements. It compares the output of a process to the specification limits by using process capability indices (PCIs). PCIs provide numerical measures on whether aprocess conforms to the defined manufacturing capability prerequisite. In this paper, a new approach based on non-central Chi-Square, ω and φ distributions is presented to design the capability control charts. The main purpose of this work is to investigate the efficiency of the proposed control charts comparing with the traditional control charts. The advantage of using the proposed capability control charts is that, the practitioner can monitor the process mean and the process variability by looking at one chart. Moreover the proposed capability control charts are easily appended to X-R control chart and provide judgments considering the ability of a process to meet requirements. To demonstrate the applicability of the proposed approach an illustrative example is conducted.