Die casting is a process in which molten metal is forced into the cavities of the mold under high pressure. The metal is hardened to the desired shape. In recent times, plastic molded parts have replaced die casting as they are cheaper and lighter than die cast parts. Die casting can be done using a cold chamber or hot chamber process.
About the die casting process
Die casting is a widespread non-expendable technique in which metal is driven into the cavity of the mold under high pressure. Die casting molds known as dies can be used repeatedly to produce castings in a variety of sizes, shapes, and wall thicknesses. The mold cavities are designed with intricate designs that allow complex shapes to be produced with precision, surface finish and attractiveness.
History of die casting
In the early days of die casting, only the low pressure injection method was used, but today high pressure casting techniques such as compression casting and semi-solid die casting methods are used to cast more than 4500 pounds per square inch. Initially, only tin and lead were die-cast, but now magnesium, copper, and other alloys can also be cast using this popular process.
Die casting process
In this process, molten metal or other materials are forced under high pressure into the cavities of the steel mold. Dies are two-part molds that are made of alloy tool steel: half clamping die and half stripping die. The die or mold is manufactured with the impression of the component to be cast. There are four types of matrices:
Single cavity to produce a component
Multiple cavities to produce multiple identical parts
Unit dies to produce different parts at the same time
Combinations die to produce several different parts for an assembly.
Molten metal is injected into the die at high pressure and high speed, helping to produce a smooth and precise casting like the original mold. Pressure is maintained on the mold until the hot metal solidifies. When the metal hardens, the die is opened to remove the casting.
There are several variations on the basic process that can be used to produce castings for specific applications. These include:
Compression casting – A method by which molten alloy is cast without turbulence or high pressure gas entrapment to produce high quality, dense, heat treatable components.
Semi-Solid Molding: A process in which semi-solid metal tickets are melted to provide dense, heat-treatable castings with low porosity.
Alloys used
Aluminum, copper, lead, zinc and tin-based alloys are mainly used in die casting.
Automation
Today, sophisticated die casting machines are used to ensure constant quality control. Each mechanized die casting differs in the method in which the molten flour is poured into the die. Automations are used to lubricate dies, for metal in the chamber, etc. Two processes called hot chamber and cold chamber methods are used for die casting.
Applications
Die casting is best suited for casting medium-sized parts with complex details. Die casting is the largest casting technique used to make consumer, commercial and industrial products such as cars, toys, sink faucet parts, connector housings, gears, etc. Most die castings are made from non-ferrous metals such as aluminum, magnesium, etc.
Advantage
Inexpensive process that can be used for a wide range of complex applications.
Parts have longer life, dimensional accuracy, and close tolerance
Post-machining can be completely eliminated
A process that can be fully automated
The mold can be used repeatedly.
Disadvantages
The weight of the laundry must be between 30 grams.
The casting must be less than 600 mm (24 in.)
High initial cost.
Limited to highly fluid metals.