Pressure die-casting includes high-pressure die-casting and low-pressure die-casting. The "die-casting" usually mentioned by people refers to high-pressure die-casting. The high-pressure die-casting process was born in the early 20th century and is a further development of the permanent mold casting process. Typical parts produced by this process include motor casings, engine blocks, office equipment and home appliance parts, hand tools and toys, etc. The unit weight of most castings ranges from less than 100 grams to about 25 kilograms.

What is High Pressure Die Casting?

The equipment cost of high-pressure die casting (especially the mold cost) is relatively high, but the labor cost is generally low because the process has now achieved semi-automated or fully automated production. High-pressure die casting is a cost-effective process for high-volume production. In this process, molten metal is forced into the mold cavity at a pressure of 0.7 to 700 MPa. Die casting machines are mainly divided into two basic types: hot chamber die casting machines and cold chamber die casting machines.

--Hot chamber die casting
The hot chamber die casting process uses a piston structure that retains a certain volume of molten metal and forces it into the mold cavity through a gooseneck and nozzle. The pressure range is up to 35 MPa, with an average of about 15 MPa. The molten metal is held under pressure until it solidifies in the mold. In order to extend the service life of the mold and accelerate the cooling of the molten metal (thereby shortening the production cycle), the mold is usually cooled by circulating water or oil through various channels in the mold block.
Hot chamber die casting is usually used to cast low melting point alloys (such as zinc, magnesium, tin, lead, etc.). Die-casting cycles for zinc alloys are typically 200 to 300 shots per hour (single shot), while very small parts such as zipper teeth can be cast at speeds up to 18,000 shots per hour.
--Cold chamber die casting
In the cold chamber die casting process, molten metal is injected into the injection cylinder (shot chamber). Since the shot chamber is not heated, it is called a "cold chamber". The molten metal is forced into the mold cavity at a pressure of typically 20 to 70 MPa (up to 150 MPa). Cold chamber die-casting machines can be divided into horizontal (as shown in the figure) and vertical types. The injection chamber of the vertical die-casting machine is placed vertically.
Cold chamber die casting is usually used to cast high melting point alloys such as aluminum, magnesium, and copper alloys, but can also be used to cast other metals (including ferrous metals). The melting temperature of aluminum alloys and some magnesium alloys is about 600 degrees Celsius, while the melting temperatures of copper-based and iron-based alloys will increase significantly.

Preparation for the high-pressure die-casting process (cold chamber)

◉ Mold making

The high-pressure die-casting mold consists of a mold base and a mold core. Its structure is the most complex of all permanent mold casting processes, so the manufacturing cycle is long. In addition, the mold needs to withstand repeated thermal shock and high pressure, which requires the mold material to have higher mechanical properties. Usually, high-pressure die-casting mold cores are made of H13, SKD61 and other materials.

◉ Metal smelting

Metal smelting is the melting process of alloys through a smelting furnace. The purpose of the smelting process is to obtain pure molten metal alloys with qualified chemical composition and suitable pouring temperature.

4 steps of a typical high pressure die casting process (cold chamber)

Spray lubricant

Inject molten metal

Shot

Push out

Advantages and Disadvantages of High Pressure Die Casting Process

-- Advantages of high-pressure die casting process

• High efficiency - Efficiency is the goal that aluminum casting companies always pursue. Although mold manufacturing takes a long time, once the mold is made, thousands or even millions of identical parts can be efficiently produced with almost no machining required because high-pressure die casting has been fully automated in mass production.
• High quality - Parts produced by this process have outstanding features such as precise tolerances, smooth surfaces, and excellent mechanical properties.
• Good economy - a set of molds can produce thousands to millions of castings, which cannot be achieved by sand casting or gravity die casting, so the cost of die castings is relatively low.
• Process simulation can be performed - With the assistance of simulation software, die-casting defects can be visually presented to mold designers, helping designers optimize mold design, thereby saving time and costs.

-- Disadvantages of high pressure die casting process

• Long mold manufacturing cycle – The manufacturing process of high pressure die casting molds takes a long time.
• High mold costs – High pressure die casting molds cost more than other casting processes, which means the process is only suitable for high-volume production.
• Limited scope of application – High pressure die casting is only suitable for non-ferrous metal casting, not ferrous metal casting.

High pressure die casting materials

Aluminum alloy: AlSi11Cu3

Material	China (GB/T)	International Standards (ISO)	USA (ASTM)	Japan (JIS)	Germany (DIN/EN)	UK (BS)	France (NF/EN)	Russia (GOST)	Italy (UNI/EN)	India (IS)
Cast aluminum alloy	YL113（YZAlSi11Cu3）	AlSi11Cu2(Fe)	A383.0	ADC12	EN AC-46100	LM2	A-S9U3-Y4	АЛ13	EN AC-46100	A383.0