Διαγράμματα ελέγχου ζωνών
Zone control charts
KeywordsΚανόνες ροών ; Μέσο μήκος ροής (ARL) ; Στατιστικός έλεγχος Ποιότητας ; Διαγράμματα ελέγχου ζωνών ; Διαγράμματα ελέγχου ροής αθροίσματος
Control charts have been widely used in industry to monitor the quality of a manufacturing process. Control charts aim to detect in time shifts of the studied parameter of a quality characteristic of a product. The Shewhart-type control chart is the most commonly used control chart in Statistical Quality Control because of its simplicity. However, it is not effective in detecting small shifts. The purpose of this thesis is the presentation of the run sum control chart which divides the control chart into regions on either side of the center line. When the chart is divided into 8 regions then it is called a zone control chart. The thesis that will follow is divided into 3 chapters. In Chapter 1 we briefly present the general theory of control charts. We mainly focus on Shewhart control charts for variables. In Chapter 2 we present the run sum control chart for the Mean and in Chapter 3 the run sum control chart for the Variance. Furthermore, we present how to calculate the average run length and through applications we compare control charts and suggest which control chart is most suitable for detecting an out-of-control process for various shifts of the mean or the standard deviation.