Permanent mold casting is a metal casting process that employs reusable molds ("permanent molds"), usually made from metal. The most common process uses gravity to fill the mold, however gas pressure or a vacuum are also used. A variation on the typical gravity casting process, called slush casting, produces hollow castings. Common casting metals are aluminium, magnesium, and copper alloys. Other materials include tin, zinc, and lead alloys and iron and steel are also cast in graphite molds.
Die casting is the process of producing large quantity of complex, intricate metal parts through the use of a die, a reusable mould created to the specific design of your component. In essence, this process works by pouring or injecting molten metal under high pressure into a mould cavity.
Gravity casting is also called permanent mold casting. The mold is made from iron, steel, resin sand. The mold is installed on a sealed furnace containing molten metal. Its pouring system consists of a riser tube connects the bottom of the mold to the molten metal bath. Once the casting has solidified, the pressure is released and the molten metal falls back into the bath, and the casting ejected in preparation for the next cycle. The pressure can be controlled and adjusted against the structure, weight and material of the casting.
Low Pressure Casting
Low-pressure diecasting or low-pressure gravity diecasting enables the tailored production of large-volume aluminum cast parts in small batches. A semi-automated procedure, low-pressure diecasting is particularly superior to the familiar method of aluminum gravity diecasting for large, rotationally-symmetrical molded parts with complex geometries. Densen manufactures aluminum alloy low-pressure diecast parts weighing up to 20 kg. Densen delivers more than just high quality cast parts – If needed, we assemble the cast parts with production parts in additional steps to form ready-to-install assemblies.
Advantages of permanent mold castings:
Permanent mold casting is an ideal option for creating custom components due to the ability to achieve the exact specifications of a complex shape or design. Permanent mold casting uses metal cores to form the interior passages within a casting, as well as shape the exterior portions of more complex shapes and designs. Forming cavities in a permanent mold casting is best done with permanent steel cores. When the design is such that permanent cores cannot be removed, destructive cores are used. This variation is called the semi-permanent mold method. Sectional steel cores are sometimes used.
The basic difference between permanent mold and die-casting is that permanent mold is a gravity feed process whereas die-casting uses pressurized injection. Gravity feed yields a denser casting. Metal molds (or dies) usually are made of high-alloy iron or steel and may have a production life of 120,000 castings or more.
Permanent Vs. Sand Casting:
Permanent mold and sand casting have similar processes by pouring a liquid metal solution in the mold to produce the permanent cast. While sand casting has been used readily for centuries, permanent mold castings usually have better mechanical properties than sand castings because solidification is quicker, and the fill is more consistent and accurate.
Less Lead Time:
Because the permanent mold itself tends to chill the molten metal, castings produced in a permanent mold are sounder than sand castings. Permanent mold castings typically require less finish work and polishing than sand castings.
Permanent mold casting are a great option for small to medium parts needing consistently good details. For pressure-tight and nonporous castings, the permanent mold process is excellent. Permanent mold castings can be stronger than die and sand castings and less porous than die castings.