Analysis and Optimization of Metal Injection Moulding Process

Abstract

Near net shape metal injection moulding (MIM) process is employed to manufacture the complex shaped metal parts and can readily be used without the requirement of secondary processes. Appropriate control at various stages (i.e. feedstock preparation, injection moulding, binding, debinding, and sintering) of the MIM process is essential to obtain pore-free structure that yield good compact in MIM parts. In MIM process, the outputs (such as, surface roughness, micro-hardness, and ultimate tensile strength) of injection molded parts is influenced majorly by injection speed, feedstock flow velocity, injection temperature and mold temperature. The present work is focused to study and analyse the effect of influencing variables of nickel based (Cr3C2-NiCr + NiCrSiB) metal injection moulded parts using statistical Taguchi method. Taguchi method is employed to conduct actual experiments and Pareto analysis of variance is conducted to analyze and estimate the significant contribution of input variables on different outputs. Taguchi and Pareto ANOVA methods determine the different set of optimal levels for each output, separately. Determining single optimal level for all the outputs is often difficult due to the conflicting requirements (maximize: MH, UST; minimize: SR) in injection moulded parts. Therefore, Principal component analysis (PCA) is applied to determine the relative importance (weight fraction) for individual outputs. Grey relational analysis (GRA) is applied to convert the multiple objective functions with different set of weight fractions determined using PCA to single objective function through suitable mathematical formulation. The grey relation grading has been determined and single optimal levels for satisfying the conflicting requirements are solved in the present work. The hybrid Taguchi-GRA-PCA method determined optimal solutions are tested with practical experiments and resulted in better metal injection mould properties. The result could help any novice user to gain best properties in metal injection moulded parts.