Moulding of SS316L surgical component using palm-stearin feedstock: Rheological analysis,process window and parametric optimisation

Metal injection moulding of a thin surgical component using a palm-stearin based SS316L feedstock was investigated. The study first determined the optimal solids loading of the feedstock, followed by examining its sensitivity to the shear rate and temperature, to ensure its pseudo-plastic behaviour. After developing the Mouldability index, a process window was established based on the experiments to present appropriate injection parameters. Using the analysis of variance, the significance and mutual coupling of each parameter was evaluated. The study found that the impact of injection speed was greater than other parameters, while holding pressure showed little effect. The verified optimised injection parameters to maximise the green density were found to be an injection temperature of 155 °C, an injection speed of 80 mm/s, a holding pressure of 83 bar, a holding time of 9 s, and an injection pressure of 132 bar, resulting in a green part density of 4.892 g/cm³.