Die casting is a metal casting process characterized by the pressing of molten metal under high pressure into a die cavity. The die cavity is made of two hardened tool steel dies that are machined to shape and work similarly to injection molds during the process. Most die castings are made of non-ferrous metals, particularly zinc, copper, aluminum, magnesium, lead, pewter, and tin-based alloys. Depending on the type of metal being cast, hot chamber or cold chamber machines are used.

There are significant capital costs associated with casting equipment and metal molds, which tend to limit the process to mass production. Manufacturing parts using die casting is relatively simple, involving only four major steps, which keeps the incremental cost per product low. It is particularly well suited to mass production of small and medium-sized castings, which is why die casting produces more castings than any other casting process. Die castings are characterized by very good surface finish (by casting standards) and dimensional consistency.

Die casting equipment was invented in 1838 for the purpose of producing movable type for the printing industry. The first patent related to die casting was granted in 1849 for a small, manually operated machine for mechanized printing type production. In 1885, Ottmar Mergenthaler invented the Linotype machine, which used a die-casting process to cast an entire line of type as a single unit. It almost completely replaced manual typesetting in the publishing industry. The Soss die-casting machine, manufactured in Brooklyn, New York, was the first machine sold on the open market in North America. Other applications quickly grew, and die-casting facilitated the growth of consumer goods and appliances, greatly reducing the cost of producing large quantities of complex parts. In 1966, General Motors introduced the Acurad process.

The main die-casting alloys are: zinc, aluminum, magnesium, copper, lead, and tin; although less common, ferrous metal die-casting is also possible. Specific die-casting alloys include: zinc aluminum; aluminum, such as aluminum that meets the Aluminum Association (AA) standards: AA 380, AA 384, AA 386, AA 390; and AZ91D magnesium. Here is a summary of the advantages of each alloy:

Zinc: Easiest metal to cast; high ductility; high impact strength; easily electroplated; economical for small parts; extended die life.

Aluminum: Lightweight; high dimensional stability for very complex shapes and thin walls; good corrosion resistance; good mechanical properties; high thermal and electrical conductivity; retains strength at moderately high temperatures.

Magnesium: Easiest metal to machine; excellent strength-to-weight ratio; lightest commonly used die casting alloy.

Copper: High hardness; strong corrosion resistance; highest mechanical properties of alloy die castings; excellent wear resistance; excellent dimensional stability; strength approaching that of steel.

Silicon-zinc alloy: High-strength alloy made of copper, zinc, and silicon. Often used as a replacement for precision cast steel parts.

Lead and tin: High density; extremely high dimensional accuracy; used for special forms of corrosion resistance. For public health reasons, such alloys are not used in food service. Type metal is an alloy of lead, tin, and antimony (sometimes with traces of copper) used to cast hand-made type in movable type printing and hot stamping. Traditionally cast in hand-drawn molds, it is now mainly die-cast after the industrialization of type foundries. [clarification needed] Ingot casting machines entered the market around 1900 and further automation was achieved, with dozens of machines sometimes operating in a single newspaper office.

As of 2008, the maximum weight limits for aluminum, brass, magnesium, and zinc castings were estimated to be approximately 70 lb (32 kg), 10 lb (4.5 kg), 44 lb (20 kg), and 75 lb (34 kg), respectively. As of late 2019, presses capable of die casting over 100 kg (220 lb) pieces were being used to produce aluminum automotive chassis components.

The material used determines the minimum section thickness and minimum draft angle required for the casting, as shown in the table below. The thickest section should be less than 13 mm (0.5 in), but can be larger.