Six Sigma Based Exponentially Weighted Moving Average Control Chart

A control chart is a statistical device used for the study and control of repetitive process. Shewhart (1931) of bell telephone laboratories suggested control charts based on the 3 sigma limits. Now the companies started applying 6 sigma initiatives in their manufacturing process, which results in lesser number of defects, are focused in identifying the causes due to assignable causes of variation. The companies practicing 6 sigma initiatives is expected to produce 3.4 or less number of defects per million opportunities, a concept suggested by Motorola (1980). If the companies practicing 6 sigma initiatives use the control limits suggested by Shewhart, then no point fall outside the control limits because of reduced variation. In this paper an attempt is made to construct a 6 sigma based exponentially weighted moving average control chart specially designed for the companies adopting 6 sigma initiatives in their organization. Suitable table is also constructed and presented for the engineers to take quick decisions.