Kesan saiz dan bentuk partikel serbuk SS316l terhadap parameter pengacuanan suntikan logam menggunakan rekabentuk eksperimen

Abstract

The Metal Injection Moulding (MIM) process is suitable for producing relatively small and complex components that require high strength and cost viability. This process, carried out in large batches, produces high density, complex and accurate shaped parts. This study attempts to optimise the processing parameters for each stage of the process using the optimisation process based on a Design of Experiment (DOE) technique, the Taguchi Method. The analysis of variance (ANOVA) is performed in order to evaluate the significance of each variable and its contribution to the quality characteristic. The green part quality characteristics such as defect free, higher green strength, green density and the final density after sintering are results obtained from the optimisation process. Water and gas atomised stainless steel powder (SS316L) in mono-modal and bimodal particle size distributions were used in this study. The binder system used is the composite binder consisting of polyethylene (PEG) and polymethyl methacrylate (PMMA). Prior to the injection moulding of the green parts, rheological investigation of the feedstocks was performed in order to obtain the suitable rheological properties before optimising the remaining processing parameter. This study exhibits that the method of metal powder production as well as the particle size distribution influences the processing parameter. The high level of significance of powder loading, mould temperature, holding pressure, interaction between injection pressure and temperature, as well as the interaction between injection pressure and powder loading to the green part quality characteristics at a = 0.01 was demonstrated by the water atomised powder in bimodal particle size distributions. However, for the gas atomised powder, the mould temperature, injection rate as well as the interaction between injection pressure and temperature is significant. In addition, for the water atomised powder with mono-modal particle size distribution, the mould temperature and holding pressure are significant for the fine powder. However, lower significant level, a = 0.025 was obtained for coarse powder where the holding time and the interaction of the injection and mould temperature are the significant parameters. The optimisation of the injection and sintering parameters made in this study has enabled to improve the sintered density of the fine mono-modal gas atomised powder compact to 99.88 % of the theoretical density, while the sintered density of the fine monomodal water atomised powder compact improved to 98.75 % of the theoretical density. In addition, the sintered density of the gas atomised powder compact in bimodal particle size distribution also improved to 99.94 % of the theoretical density while the water atomised powder compact under the same particle size distribution improved to 98.66 % of the theoretical density. The study results showed a better sintered density as compared to the previous studies and it is demonstrated that the optimisation of the moulding and sintering parameter with the Taguchi Method has enabled to improve the green part’s mechanical properties as well as the sintered density that was close to SS316L theoretical density.