The Comparison of Medical Grade PP with Common Grade PP in Injection Moulding Process

Abstract

Polypropylene (PP) is used to make a syringe and its tray, and there are two varieties of PP: medical grade (LB6331) and common grade (TP340). Although these two materials are basically similar, their characteristics differ significantly and have an impact on overall performance when made using the injection moulding process. The traditional trial-and-error method for optimising PP syringe and tray manufacture is often costly and time-consuming. This research is being done to create a numerical study using ANSYS Fluent on finding the best material to mass-produce the syringe and its tray to come up with a solution to lower the cost and time it takes to make the much-needed virus-fighting equipment. The objectives of this study are to compare the two types of PP's viscosity during injection moulding with ANSYS Fluent, to determine any incomplete fillings of both types of PP viscosity during injection moulding in the mould with ANSYS Fluent, and to compare the time taken between the two types of PP to fill up the mould casing. In the simulation, the temperature for both materials are set as 190 °C, and the parameter inserted beforehand are followed using the cross-parameter table, which contains zero shear viscosity, power-law index, and time constant for the temperature. A constant gauge pressure of 38.22 MPa is inserted as the inlet boundary condition for the simulation, along with the temperature of 190 °C. The results revealed that the time taken for the molten LB6331 to be fully injected into the mould is 1.5 seconds while for molten TP340 is 4 seconds. The viscosity of LB6331 at 2500 s-1 is approximately 220 Pa.s while the viscosity of TP340 is approximately 350 Pa.s. Both PP are shear thinning because their viscosity decreases with increasing shear rate. The VOF for both simulation of LB6331 and TP340 showed that there are imperfections at the edge of the mould casing because that part still contains air.