What Is Die Casting?

This article describes in detail the definition, types, process, materials, molds, advantages and disadvantages, applications of die casting in the form of text + pictures. If you want to understand die casting process more clearly, this article will help you a lot.
die casting process


Die casting is a molding process in which molten metal is injected into a mold cavity by pressure and cooled and solidified under pressure to obtain a part. Die casting process has three main components: die casting material, die casting mold and die casting machine.

Die casting materials

Die casting materials include zinc, aluminum, magnesium, copper, tin, lead, etc. Among them, zinc and aluminum alloys are the most widely used, followed by magnesium and copper alloys. We need to choose the right material based on the performance requirements of the part.

Aluminum alloy. It has good casting performance, low density, wide application, excellent thermal conductivity, electrical conductivity, corrosion resistance, and easy machining. Common aluminum alloys include ADC12 (A383), ADC10 (A380), A356, A360, AlSi9Cu3, etc. Aluminum die casting has a wide range of applications.

Zinc alloy. It has high density, low melting point and good fluidity, and can be used to die-cast complex, thin-walled and precision parts. Zinc alloys are easier to undergo surface treatments such as welding and electroplating. Common die-cast zinc alloys include Zamak 2, Zamak 3, Zamak 5, ZA-8, etc.

Magnesium alloy. It has low density, excellent shock absorption and processing properties, and is widely used in mobile phones, communications, medical and other industries. Common die-cast magnesium alloys include AZ91D, AM60B, AM50A, AS41B, etc.

Copper alloy. It has high melting point, good electrical and thermal conductivity, high mechanical properties, easy machining, and relatively high raw material prices. However, the life of copper alloy die-casting molds is low, about 2,000 times. Common die-casting copper alloys are CuZn25Al5, CuZn35Al3 and so on.

These die casting alloys have different physical and chemical properties, you can choose the right material according to the specific application requirements.

Types of Die Casting

According to the different working principles of die casting machines, we often divide the die-casting process into two types: cold chamber die casting and hot chamber die casting.

Cold chamber die casting

Cold chamber die casting process is mainly used to cast metals with high melting points, such as aluminum alloys (melting point 660°C), magnesium alloys (649°C), and copper alloys (melting point 1084°C). The metals are melted in a separate crucible and then injected under high pressure into the mold cavity to form the casting.

Hot chamber die casting

Hot chamber die casting process is mainly used to cast some metals with low melting points, such as zinc alloy (melting point 420°C), lead alloy (melting point 327°C), etc. Hot chamber die casting uses less pressure than cold chamber die casting when injecting molten metal, but its work efficiency is higher than cold chamber die casting. Cold chamber die casting machines complete an average of 80-100 injections per hour, while hot chamber die casting machines complete 400-1000 injections per hour.

Die casting mold

The die casting mould is a very important part of die-casting, which determines the shape, size and tolerance of the castings. Die-casting molds are usually made of H13, SKD61 and other steel materials through CNC machining and heat treatment. Die casting molds have many production steps, long cycle times and high costs, and are only suitable for mass production.

Die casting process steps

step1 Melting: Heating the metal material to a molten state.
step2 Prepare the mold: Check the status of the mold to make sure it can work
step3 Pouring: Inject molten metal into the mold.
step4 Injection: Fill the mold cavity with metal through high pressure.
step5 Close the mold: The metal cools and solidifies in the mold.
step6 Open the mold: Open the mold and take out the casting.
Step7 Inspection and cleaning: Check the quality of castings and remove burrs.
Step8 Surface treatment: Some parts require surface finishing such as shot blasting, sand blasting, powder coating, and electroplating.
Step9 Packaging and shipping

die casting diagram

Advantages and disadvantages of die casting

Advantages of die casting

High efficiency: Rapid injection, cooling, solidification, one-time molding, significantly shorten the production cycle of parts.
High flexibility: Die casting can produce a variety of complex shapes and different sizes of parts to meet the needs of different industries.
High precision: Die casting parts size precision, low surface roughness
High material utilization rate. Defective die castings and blanks can be recycled and reused, but their proportion cannot exceed the proportion of pure materials.
Suitable for mass production. When parts are cast in large quantities, the cost advantage of die casting becomes apparent, and it can significantly reduce the cost per unit product.

Disadvantages of die casting

Die casting material is limited. Not all metals are suitable for die casting, at present the main materials are aluminum alloy, zinc alloy, magnesium alloy and copper alloy, ferrous metal is rarely used.
Die casting parts have some defects. Under high pressure and high speed, it is easy to involve air when injecting, so there are defects such as porosity and shrinkage in die casting. But the emerging squeeze casting process can effectively eliminate these defects, it can cast higher performance, heat treatable parts.
Not suitable for small batch production. Because of the high cost of die casting molds, there is no cost advantage in small batch production.

Die casting applications

Due to the advantages in manufacturing process, die casting is widely used in many industries, such as automobile, electric car, communication, home appliance, hardware products, power tools, IT and lighting lamps.

Automotive industry: Die casting can help the automotive industry to realize light weight, many auto parts are completed by die casting, such as crash beams, doors, gearboxes, cylinder heads, pistons, radiators, motor housings and so on.
Electric car industry: Electric cars need die casting process more. Die casting factories even use 8,000 tons of die casting machine to cast out the entire body frame. Moreover, batteries, motors and inverters and other core parts of the shell are completed by die casting.
Communication industry: Many parts of the communication equipment, such as cell phone shell, router shell, etc., also use die-casting process production. These parts need to have lightweight, beautiful and other characteristics, die casting process can realize these requirements.
Household appliances: In the production of household appliances, die casting process is used to manufacture a variety of parts, such as electric fan base, washing machine base, etc.. Die casting process can provide high precision and high quality parts, improve the performance and reliability of household appliances.
Lighting industry: LED lamp shell, radiator parts are also used die casting process production. Die casting can realize the demand for high precision and beautiful appearance of these parts.

In addition, die casting is also required in industries such as medical devices and aerospace. Overall, if you want to quickly finish parts with complex shapes, precision, and smooth surfaces, the die casting process will be a good choice.

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Eric Zhou

Focus on providing squeeze casting, aluminum die casting(hpdc+lpdc), mold making, CNC machining, and sheet metal fabrication solutions. If you need help, please feel free to contact us!

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