High Pressure Die Casting (HPDC)
High pressure die casting is a manufacturing process is fast and inexpensive relative to other casting processes. Molten metal is injected into a steel mold or die using extreme pressure between 1500 and 25000 psi. Due to this extreme pressure, the die will fill quickly, producing fast cycle times. The result cast has dimensional accuracy and the smooth surfaces. The cast is so good that most castings require no machining . Flash still may need to be removed.
High pressure casting is a four step process. First, the die is prepared by spraying the mold cavity with lubricant. The lubricant allows the cast to be easily removed from the mold. In addition, the helps control the temperature of the die. Next the mold is filled with molten metal under extremely high pressure. Once the mold is completely filled, pressure is maintained until the metal solidifies. Then the die opens and the cast is ejected by ejector pins. The final step is to separate the scrap, which includes the gate, runners, sprues and flash. This is often done using a special trim die in a power press or sawing and grinding. This scrap is recycled by re-melting it. Most die casters perform other secondary process to create a more finished product such as tapping a hole, polishing, buffing, or painting.