Análise de desempenho dos gráficos de observações individuais no controle da composição química do carbono de ligas especiais em um processo de fundição

Abstract

This study analysed the performance of individual observations graphs in control of the carbon chemical composition of the particular alloy in a casting process. Due to the fact that the displacements that occur in the middle of the process are difficult to detect. It is aims to verify the improvement obtained in the detection power of the individual values of control chart by changing to its width. To achieve this goal it was necessary to confirm the normality of the data change, the width changes of the individual values of control chart and verify the improvement in the Average Run Length. The study was developed with theoretical basis in the main authors of the subject and literature review of the quality history; statistical process control and control chart performance analysis. The research methodology is classified as exploratory applied research and finally a case study. Through the performance graphs’ analysis of individual observations, it was observed that the decrease of the chart width, it is possible detect the displacement on the process average with less samples.