Cusum control chart in the analysis of a coffee manufacturing process

Abstract

This research deals with an empirical application using the statistical control chart of accumulated sums process, to evaluate the stability of a production process of instant coffee production. This control chart in the form of the V mask is suitable for autocorrelated production processes. The sample collected in the investigated production process corresponds to a total of 4,650 observations and the characteristic researched corresponds to the weight of the 50g and 100g instant coffee powder cans. Data collection was performed automatically during a period of 6 consecutive months. The residues were obtained from the estimates of the third order autoregressive models AR (3) and were analyzed using the accumulated sums control chart, which evidenced a productive process considered statistically unstable, thus corroborating the fragility of this process regarding guaranteeing non-compliant products, especially regarding the weight of 50g containers. The results suggest a greater attention from the coffee industry employees, thus giving greater attention, with discipline and control in daily activities, as well as decimating relevant mistakes made by employees in their work routine and which may be addressed with good guidance and behavior change.

Keywords: Control Charts. Accumulated Sums. Coffee Production. Statistical Process Control.