Statistical Quality Control and Process Capability Analysis for Variability Reduction of the Tomato Paste Filling Process

Abstract

In this research some techniques for process statistical control were applied, such as frequency histograms, Pareto diagrams, process capability analysis and control charts. The purpose of this investigation was to reduce the variability of the canned tomato paste filling process coming from a tomato processing food industry that has problems with the net weight of their processed product. The results of the process capability analysis showed that 35.52% of the observations were out of the specifications during the months in study, which generates a real capability of the process (Cpk) of 0.124, and it indicates that the process does not have enough ability to fulfill the required specifications by the firm. The process potential capability (Cp) is 0.676. Given that Cpk < Cp, then it is concluded that the process is not centered, indicating that the measurement of the filling process is away from the center of the specifications. The process fits 0.371 sigma between the process mean and the nearest specification limit. It was estimated that 40.42% of the cans produced during February did not meet the specifications required, and neither did a 16.84% during March. In consequence of this, it was necessary to identify the potential causes of the can excess fillings. Afterwards, it was proposed an orthogonal array L9 to adequate the process to the company filling specifications. The optimum operating conditions achieved a 5.28 sigma process quality. In addition, it was noted that the process had only 77.49 parts per million (ppm) out of specification. This situation places the tomato paste filling process as a world class quality process.