Metal die casting is a systematic process for producing a wide range of metal parts. This technique makes it easier to produce strong, precise, lightweight metal components at a lower cost. The parts or components produced by the die casting process facilitate the production of both consumer and industrial components.

Although metal die casting is a flexible manufacturing process, it is recommended that you have a good understanding of the technique before using it on your own or employing companies that provide related services. So what is die casting, how does it work and what are the different types and benefits? Read on to find out.

What is Die Casting?

Die casting is the process of using high pressure to force molten metal into a mould. A hydraulic press, which ensures that the closing surfaces meet almost perfectly to form a seal, forces together the hardened tool steel pieces that make up the cavity.

Metal die casting allows the production of precision metal parts with excellent finishes and accurate dimensions. It is ideal for high volume production because of its ability to create complex parts.

Which Metal Materials are Used on Die Casting?

Aluminum

Aluminium is a primary metal in die casting, used in alloys for the cold chamber die casting process. These aluminium alloys typically contain elements such as magnesium, copper and silicon.

Aluminium-based die casting alloys are an excellent choice for intricate, finely detailed parts because they are lightweight and offer excellent dimensional stability. They have robust resistance to temperature changes, corrosion, electrical and thermal conductivity. Here are some commonly used aluminium die casting alloys.

  • Aluminium Alloy 380: An all-purpose aluminium alloy with a balance of castability and mechanical properties, 380 is widely used to make engine brackets, furniture, electronic housings, frames, handles, gearboxes, power tools and more.
  • Aluminium Alloy 413: It has excellent casting properties due to its high pressure compressibility. AL413 is commonly used in the manufacture of architectural components, food machinery and hydraulic cylinders.
  • Aluminium Alloy 443: Of all the aluminium alloys used in die casting, AL443 offers the best ductility. This makes it perfect for consumer goods, especially those that require plastic deformation after casting.

Zinc

Zinc alloys make up a significant proportion of die casting metals. They are easy to manufacture, suitable for hot chamber die casting and offer additional benefits such as impact strength, ductility and plating compatibility. Here are some typical alloys used in zinc die casting.

Steps Involved in the Die Casting Operation

  • Create Mold
  • Clamping
  • Casting
  • Cooling
  • Ejection
  • Trimming

Types of Die Casting

The two most commonly used die casting processes are hot chamber and cold chamber. Each is unique and suitable for different scenarios. Here is what these two categories of processes involve:

Hot Chamber Die Casting

The hot chamber die casting process is ideal for low melting point materials such as magnesium alloys, tin, zinc and lead. This is to prevent damage to the pump which could occur when it comes into contact with metals or alloys with a higher melting point. Injection of the molten metal into the mould is achieved by applying pressure from a hydraulic system.

Cold Chamber Die Casting

Cold chamber die casting is the ideal method when working with high melting point materials such as aluminium. As the high temperature required to melt these materials can damage the pumping system, this process is perfect for such metals.

It is a high pressure die casting process in which the molten material is poured into a cold chamber and then injected into the mould. The hydraulic system used in a cold chamber process is similar to that used in a hot chamber process. However, a higher pressure of between 2000 and 20000 psi may be required.

Different Variations of Die Casting

The following variations were suitable for dealing with defects, mishaps, distortions and other problems that could occur during the casting process.

  • Semisolid Die Casting(SSDC)
  • Vacuum Die Casting
  • Squeeze Die Casting
  • Gravity or Low-pressure Die Casting

Benefits of Die Casting Process

Good mechanical properties: Die casting produces parts with good mechanical strength, although not as strong as forged parts. It can also produce parts with improved conductivity, hardness and durability.

  • Excellent finishes: Die casting allows the rapid production of complex parts with smooth or textured finishes, depending on your requirements.
  • Fast lead time: Once the die is ready, the average die casting process cycle is quite short, often only a few days, depending on the size and properties of the material.
  • Cost effective: Die casting is very cost effective, especially when produced in large quantities. The cost per part decreases significantly over time.

Limitations of Die Casting Process

  • Limited use of materials: Die casting only works with metals that have a high degree of fluidity, which limits the number and type of materials that can be used in the process.
  • Labour intensive: The process requires constant monitoring and supervision, particularly during the cooling phase.
  • Non-alterable dies: Because dies are made of hardened steel, they cannot be modified or adjusted. They are also expensive to manufacture.

Surface Finish Options for Die Casting

  • Powder Coating
  • Plating
  • Antiquing
  • Painting

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