Quality Engineering of Impellers used in Water Pumps - A Taguchi Approach

Impeller is a vital component of water pumps and its dimensional accuracy is of utmost importance for reliable working of water pumps. Variation in dimension (Outer Diameter) results in poor fit of the impeller and causes low water discharge as well as reduction of impeller life. More importantly, due to poor fit, impeller jams with the shaft and may damage the entire water pump, resulting in functional&financial losses. Application of conventional quality techniques of Statistical Process Control has not been able to improve the dimensional accuracy. Taguchi technique of quality engineering has been used to design an improved manufacturing process and to reduce the variation in quality. Taguchi techniques incorporate adjusting the Target Control Factors/Variability Control Factors at their optimum levels, so that the quality characteristics can be always on target. The OD of the Impeller is mainly affected by Temperature&Pressure (each having 2 levels) settings. Using DOE technique, an experiment is designed as per the L₄(2²) standard Orthogonal Array and the analysis of results is done through ANOVA technique. From the analysis, Temperature emerges as the most significant factor in varying the Outer Diameter. Setting the melt temperature at 320°C results in zero error impellers.