Suspecting Dominant Variable that Causes Porosity Defect in a Cast Made up of Aluminium Alloy (Lm2) Using Shainin’s Doe Approach
High pressure die casting (H.P.D.C.) cold chamber process, producing aluminium alloy casts face rejections and
rework due to the inherent casting defects related to die design and machine process parameters in the foundries. This paper
explores the influential process parameter(s) that scale down the quality of the cast by producing porosity defect on the
critical region of the component casted from aluminium alloy (LM2). In optimizing the casting process in the study, the key
process parameters or the suspected source of variation (S.S.V.),causing variables selected in the first stage are pouring
temperature, punch and cavity side temperature of critical area of cast. In the second stage, plunger speed, intensified
pressure and die coat application are selected. Implementing Shainin’s DoE methodology of Red X, based on progressive
elimination search principle, yields 86% improvement over average rework rate and around 75% improvement in average
rejection rate. The critically influential factors identified are plunger speed as solid Red X i.e. dominant variation causing
variable, cavity side temperature just before closing and intensified pressure found as Pink X and Pale Pink X.
Index terms- Pareto Principle, Product/Process search, Variable search, Shainin approach.