Development of a continuous control chart for the electric testing machine in the harddrive manufacturing line

Abstract

In this study, an algorithm has been developed to systematically detect the change in the process capability. The proposed model makes use of the shewhart control chart (namely p-chart) and cooperate the statistical hypothesis testing, to remove human decision of whether the process mean has changed. Currently, most manufacturing are using SPC as a mean of process control. To make SPC dynamic, many manufacturers schedully modify their control chart, i.e., changing center line, upper and lower control limit, based on data from last 2 shift of production. This practice has been observed in a disk drive component factory selected for this study. In this factory, parts are produced in large quantity and most control data are automatically collected and stored in network (for SPC and other use). It is not unusual for drive component manufacturer to have production lines and hundred of testers. Hence, a manual SPC’s are not suitable nor effective in this type of industry. This problem has been overcomed by introducing hypothesis method into the standard Shewhart SPC. This enables the development of systematic model in detecting process mean shift for a specify level of confident. The propose model are verified using from Electrical Testing Machine of a HGA Assembly process. The result is satisfactory.