In this study, various flow restrictor geometries were implanted in the runner system of an injection mould with gates of different configurations to attain an optimised runner design and alleviate warpage in plastic lenses. The injection moulding simulation package used was Moldex3D, with the process parameters chosen being that of size, shape and position of the flow restrictors with the geometry of those gates. The result of the analysis by Taguchi experiments suggest that the optimised runner design is a cylindrical shaped restrictors at secondary and quaternary runners, with the end of restrictor aligned with the edge of tertiary runner, and a gate of fan-converge shape. The warpage of the lens was reduced by 28.6% using the optimised combination of the parameters, compared with the warpage using the original parameters.
