Molds for injection, thermoplastic, thermoset, blow, or reaction molding typically are manufactured from metallic materials such as steel, stainless steel, aluminum, or copper based alloys. These materials possess properties suitable to a wide variety of mold tool requirements. Thermal conductivity, strength, hardness, machine-ability, durability, and cost are primary considerations. Molds typically have two halves and a core. These components mate with each other in a sealed off fashion. When in the closed condition, a cavity exists between the two halves. This cavity defines the product to be molded. Complex products may require additional mechanical actions to create special features.
Electrically heated manifold systems internal to the mold are often utilized to deliver hot melted resin from an injection press nozzle to the cavity through a series of channels in the mold manifold. After the mold opens and the molded part has cooled adequately, mechanical pins or other means eject the part from the mold. The time required to cool the part is determined by the capability of the heat management system incorporated in the mold. Typically, molds have a bore or series of bores in the core blocks for carrying a coolant. The coolant extracts heat from the molded product during the molding cycle. These bores are designed in various configurations utilizing accepted fluid dynamic physics. System layouts can include serial bores, parallel bores, or a combination of both. Serial systems link one or more bores in sequential order, referred to as a circuit with bore size remaining constant. Parallel systems supply fluid via larger bores to a series of smaller bores, similar to lawn irrigation systems.
These serial and parallel systems, however, are designed with the limitations of traditional manufacturing technologies such as drilling. Drilled bores are generally limited to being straight. Therefore, to achieve a non-linear bore, a series of intersecting bores must be drilled. The series of intersecting bores are unable to follow the smooth irregular contour of many molded parts and, consequently, cannot achieve uniform heat transfer.
Other established mold design/manufacturing techniques additionally utilize conventional or computer controlled machining to cut square or “U” shaped channels through plates, cylinders, cones, and other mold components. A plurality of mating plates are then stacked to cover the open side of the channel. “O” rings or other gasket materials are utilized to seal the mated plates. The molded part surface is generally on the opposing side of the plate or component that has the channel machined through it. While this allows more complex cooling systems to be created than the conventional drilling technique, it is limited to generally flat or cylindrical conditions and cannot consistently follow free form shapes.