The application of U-shape milled grooves for cooling of injection moulds

Abstract

In the injection moulding process, productivity and part quality depend largely on the cooling system of the injection mould. Several cooling methods are being adopted by the mould industry, with the straight-drilled cooling channels method being the most popular. Many reported research activities have been based on this method, but the method has several limitations that prevent it from achieving efficient and uniform cooling. In the present work, a U-shape milled groove method was proposed for large and complicated parts, especially for parts with large freeformed surfaces. Simulations were made to compare the cooling effect of U-shape milled grooves with that of straight cooling channels using COSMOS/DESIGNSTAR, an analysis software based on the finite element method (FEM). The heat flux was calculated on a cycle-averaged basis and the natural convection between ambient air and the exterior mould surface was ignored. A mouse cover was used as a case study. The U-shape milled grooves were found to have better temperature control than straight cooling channels. The temperature distributions of the core and cavity with U-shape milled grooves were more uniform than with straight cooling channels. Moreover, the U-shape milled grooves removed the heat efficiently; the mould temperature was lower than that with straight cooling channels. The U-shape milled grooves method has demonstrated its advantages in mould cooling. Although U-shape milled grooves need to be machined using computer numerical control (CNC) machines and more machining time is required, making them more expensive than straight cooling channels, their potential benefits will be explored for practical applications.