Implementation of statistical process control in an Indian tea packaging company

Abstract

A major quality problem faced by tea packaging units is control of weight variation in the tea packets. When the weight variation in tea packets is high, it is likely that buyers get under weight packets in some segments of the market and over weight packets in some other segments. Although an average consumer may not notice the difference, packet weight below certain limit may require the company to pay a substantial amount as fine to the government regulating agencies that conduct such audits. At the same time over weight packets constitute an additional loss to the company. Although control charts are well suited to help control such weight variation, their successful implementation at the machine requires a user-friendly approach for the operators who need to maintain it on a daily basis. This paper discusses one such application where using X-sum control chart, out-of control situations are reduced from over 66% to about 4%.