The Basics of Die Casting
Die casting is a manufacturing process used to create metal parts and components through the use of molten metal being injected or forced into a steel die that has been shaped to the exact specifications of the desired part. The process is capable of producing highly precise and complex geometry with good surface properties, as well as internal cavities and passages.
Die casting is a great choice for high-volume runs of parts. It offers short lead times for tooling and efficient production runs for thousands or even millions of parts. Die casting can be used for aluminum, magnesium, lead, zinc, and copper alloys, however, the most common is aluminum alloy.
There are two types of die casting: hot chamber and cold chamber die casting. In hot-chamber die casting, molten metal is injected into a chamber that has been preheated to keep the metal around its liquidus temperature. Cold chamber die casting is required when the material used has a higher melting point than the preheated chamber, and an external injector forces metal into the furnace before injecting it into the chamber. In either process, pressure is maintained during solidification to ensure the liquid metal fills the die.
The die casting process begins with metal in liquid form, usually in an oven or crucible. It is then heated to temperatures ranging from 500-900°C, depending on the metal and alloy used. The molten metal is then injected into the mold cavity, where it is cooled and solidified into a part. As the metal cools it shrinks, creating a tight fit in the mold, and enables the die caster to repeat precise components of the same size and shape each time.
The tooling required to cast a part includes two dies - the “die cavity” and the “core” - along with a powerful injection system. The die cavity is the negative side of the mold, which gives the part its shape, and the core is an insert that is used to shape the interior and complex features. The cavity and core are typically machined out of steel, but other materials such as brass or aluminum can be used depending on the intended use.
During production, operators must monitor the grade and type of metal being used very carefully in order to ensure quality parts. The pressure must also be kept in a certain range during production in order to achieve solidification and avoid pressure drops. This constant monitoring of the variables allows the die caster to produce parts with tight tolerance, complex shapes, and uniform strength.
The die casting process can be conducted with open and shut, slush, and etching tooling. Open and shut tooling allows for the production of a single, or a limited quantity, of parts. Slush casting is used for creating thin-walled hollow parts such as toys or figurines, and requires a high degree of accuracy and detail. Etching involves the use of an acid resistant material painted on the surface of the die cavity, allowing the creation of intricate patterns and textures.
Die casting is one of the most economical, efficient and cost-effective ways to create large quantities of parts, with a very high degree of accuracy and detail. With the right conditions and right equipment, a die caster can produce thousands of parts in a short amount of time with a high degree of quality, making it an ideal choice for mass production.
