Estimation of Labor Work Activity Based Defect Rate in Part per Million Process

Due to major in improvement in manufacturing process during the last decade, many manufacturing companies performance have achieved a very low defect rate around one to three percent. However, the lower defect rates are, the higher the pressure from customers in zero defect delivery. To ensure highest customer satisfaction and quality reputation, quality related activities, such as product inspection, process monitoring, and process adjustment, are added into typical production activity. Since problems related to product quality seems to occur randomly. It is very difficult to determine the appropriate number of operators in particular when the given production line produce several products that has different characteristics in product quality problems. This research aims to develop an estimation method that provide a required time for defect correction and inspection related activity. By using statistical techniques, the distribution of each defects are identified. Then, the probability of defect occurence based on production target can be estimated. The time of the operator activity related to each defect can be estimated based on this probability and standard correctioin time. In this research, in certain types of defects can not be directly identifed its distribution. As a results, central limited theorm has been brought to identify the rate of defect, such as piece per hour, in normal distribution form. To validate, this proposed method in estimated the time of defect correction activity is compared with time motion study method.