Reducing scrap by using statistical quality control techniques: A case study on synthetic sack production

The work described in this thesis investigated how to implement statisticalquality control (SQC) tools for the purpose of minimizing scrap in poly-propilen(PP) bag (sack) production systems. The study, provides a better understanding ofusage of statistical techniques for decreasing scrap loss in production line. Ahistorical data from the subprocesses collected and SQC problem solving tools wascarried out on it.A production process composed of subprocesses is a common phenomenon inindustry. Each of the subprocesses contributes to various aspects of product quality.Ideally, a control chart can be set up on every subprocess to guarantee the quality ofthe final product. This is not practical, because of limited human and economicresources, and the management has to decide which subprocesses are to be givenhigher priorities. Priority determination methods have to be defined in eachorganization. Recently, it has been suggested that SQC techniques should be usedfor priorization to reach organizations? objectives and competitiveness throughmarket by ISO 9001:2000 Quality Management System standard and 6 SigmaExcellence Model. Implementation of such systems requires knowledge of basicstatistical methods. In this thesis, it was implemented the priorization tools on PP bagproduction company as suggested above standard and model to reduce scrap loss.Scrap loss decreased 35 % in factory at the end of these implementations.Keywords: Statistical quality control, scrap, sources of scrap, production.