Reliability Issues of Impellers used in Water Pumps - Taguchi Quality Engineering Techniques

摘要

This paper aims to address the issue of variation in Outer Diameter of the Impellers used in water pumps, which hitherto has not been resolved through SPC, by employing Taguchi Techniques of Quality Engineering. The dimensional in-accuracy of OD 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. The main factors affecting the OD -Temperature & Pressure (each having 2 levels) - are determined by brainstorming sessions. Using DOE technique, an experiment is designed as per the L4(22) standard Orthogonal Array and the factors (including the interaction) are assigned through the factor assigning table. The trials are conducted by selling the two factors at their various levels and the results are analyzed through ANOVA technique. From the analysis, Temperature emerges as the most significant factor in varying the Outer Diameter. Confirmatory experiment is conducted by selling the melt temperature at 320oC and it is verified that the variation in dimensional accuracy of OD is less than 0.01%. The shape of the impeller is also optimal. Besides, the concentricity is reduced to approx. 0.05 mm., which is the industry target.