Quantitative evaluation of quality loss for fraction defective case using Taguchi's quality loss function

Abstract

The conventional perception about the quality of the product was concentrated only around the specification limits. If the product characteristic was within the specifications, it was found to be good and accepted for use. If it did not meet the specifications, the product was rejected, or reworked and used. This is the concept of step function. Taguchi’s quality loss function, which is quadratic in nature, evaluates the quality even when the product characteristic is within the specification. This paper discusses the application of Taguchi’s quality loss function to evaluate the quality loss during spline hobbing operation of a shaft manufacturing process. The quality characteristic considered here is fraction defective type. The fraction defective data has been collected from five industries manufacturing the same kind of shaft; Taguchi’s loss function has been applied and average quality loss has been calculated for each of the industries. The loss function graphs are constructed for these industries for the purpose of comparison. Using the loss function, the industries having a comparatively larger quality loss are identified and necessary action has been suggested to improve their product quality.