Dynamic temperature control in injection molding with new conformal heating/cooling system

Résumé

The cooling is an important process in injection molding. It can represent more than 60% of the total molding cycle time, affecting directly the shrinkage and warpage of the plastic part. Therefore, designing a good cooling system is very important as it greatly affects the cycle time, the quality and indirectly the price of the product. Conventional straight cooling channels are machined into mold components with gun drills. Alternative methods to create cooling channels that conforms or fits to the shape of the cavity and core of the mould providing better heat transfer have been proposed before. This paper deals with a new cooling system that follows the shape of the part in core and cavity. This alternative method uses a metallic mold with thin walls, to increase the heat absorption from the molten plastic and reduce thermal inertia, mounted in a chamber constructed from a thermo-insulating material. Between the active elements of the mold and the exterior chamber a heating/cooling fluid is circulating. This ensures quasi isothermal filling conditions and a uniform as well as a more efficient cooling process.