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What is Die Casting? Processes, Materials, Applications, Costs

Die casting is a process that promises high-performance metal parts. By using this method, you can make robust components for different industries at an affordable cost. The best part is that it is not as complex as other molding procedures, and the results are permanent. To help you understand the process, keep reading as we uncover what die casting is, the different processes involved, materials, applications, and how much it takes to make them.

What is Die Casting?

A detailed diagram of a die casting system showing components such as the punch, casting, runner, and gating, highlighting the intricate engineering

It is a process by which you can make things of different shapes by pushing molten metal using high pressure. An example of this is aluminum alloy cylinder heads. 

Die casting can be used to produce commercial, industrial, and consumer goods. 

The Die Casting Processes

Die casting employs two types of machines to produce metal casts in two different ways:

  • Hot Chamber
  • Cold Chamber

Hot Chamber

the hot chamber die casting process, where molten metal is forced into a mold cavity by a plunger through a gooseneck passage

Also known as the gooseneck casting or hot die, metal is heated in a furnace that is further connected to a casting machine. The molten metal is then introduced into the die mold using high hydraulic pressure.  

With the help of this process, one can aim to create some intricate shapes. High-grade materials that have low melting points are ideal for a hot chamber.

Alloys suitable for hot chamber: zinc, lead, tin, and magnesium.

Advantages of Hot Chamber Die Casting

  • High-quality products are produced with minimal or no post-processing requirements. This also helps save time.
  • It is an efficient process. 
  • The process is faster. About 18,000 shots can be produced every hour for smaller components.
  • Versatile process. Various shapes, as well as geometries, for a wide variety of components and parts can be produced.
  • Little wastage. 
  • The die lasts long since the melting point is low.

Disadvantages of Hot Chamber Die Casting

  • It can turn expensive as the initial investment in tools is high. So, it works more for large-scale production only.
  • The choice of materials is limited since the machine requires only low-melting-point materials.
  • There is a limitation on the size and complexity of the parts due to the low metal fluidity. 

Cold Chamber 

a hot chamber die casting machine, which include a gooseneck, nozzle, plunger, and chamber

Another type of die-casting process takes place in the cold chamber. In this, the molten metal is added to the shot sleeve with the help of a ladle, either by hand or automatically. This is followed by the propelling of the metal into the die mold. There is minimal contact between the injector components and the hot metal, and this helps in prolonging the life of the metal. 

Advantages of Cold Chamber Process

  • The parts are robust and lighter. They do not need additional processes such as fastening or welding.
  • They are durable and stable and are resistant to heat.
  • The production rate is high with machining involved. 
  • Complex shapes can be produced with no need for additional tools.
  • It facilitates multiple finishing techniques, such as smooth or textured. Each finishing requires little to no preparation. 

Disadvantages of the Cold Chamber Process

  • The cycle time is less than the hot chamber.
  • It is expensive as the cost of casting the die is high
  • It occupies more space
  • The machine needs to be operated manually 

Materials Used in Die Casting

The die-casting process uses both ferrous and non-ferrous metals. However, that doesn’t mean you can use any material. In fact, you can only pick materials such as copper, iron, magnesium, zinc, aluminum, lead, silicon, and tin. These can be heated to a certain melting point and then pressed into differently shaped molds. 

Different Types of Materials Used in Die Casting

Aluminum

Different Types of Materials Used in Die Casting

Aluminum is one of the most extensively used materials for die casting process. One, it is highly inexpensive, and two, it is light in weight and also good for the environment. Aluminum alloys comprise copper, magnesium, and silicon and are more suitable for the cold chamber die-casting process. 

Other properties that set them apart include high thermal conductivity and resistance to corrosion. The manufacturers can experiment with different geometries as the material possesses high dimensional stability and is thin.

Some of the most commonly used aluminum alloys are 380, 390, 413, 443, and 518. 

Magnesium

various magnesium die-cast parts

Another popular die-casting material is magnesium. It is the eighth most abundant element found in the Core of the Earth. What makes it so usable is that it weighs even less than aluminum. Apart from this, an added advantage of magnesium is that it is easy to machine. 

This ability of machining makes it highly functional for industries that need cast parts with extra details or surface finishing with machines. Magnesium is thus more vividly used in hot chamber die casting. Some of the elements found in magnesium alloys include zinc, aluminum, silicon, and manganese. 

A few magnesium alloys that are employed in die casting are AZ91D, AM60, and some rare earth alloys such as AS41B and AE42.

Zinc

Some of the most easily castable alloys fall into the category of zinc. Though used in the hot chamber die casting process, it is still a favorite among manufacturers who look up to it due to its many advantages. These include ductility, high strength, and suitability. Not only this, zinc alloys do not face much wear and tear.

Zinc, as we know, is used in place of iron and brass due to its ability to be cast into decorative and practical parts. Remember, it is not as light as aluminum or magnesium and comprises copper, magnesium, and aluminum. 

The alloys of zinc include names such as Zamak 3, Zamak 2, and Zamak 5. 

Other alloys used for die-casting

Tin

A non-toxic material that can be combined with other materials easily is your tin alloy. The material has a low melting point with excellent molten fluidity. It readily forms alloys with other materials, making it one of the most sought-after when it comes to die casting.

It is used as one of the materials for soldering and can also be used to cast iron. Also, the dimensional stability is high. Even if it shrinks during manufacturing, there is no harm as shrinkage akes place during solidification.

Lead

This metal can handle corrosion like no other alloy. It is this property that makes it useful for making bearings, ornamental items, and fire safety equipment. However, lead is not recommended for parts that may come in contact with food. 

Applications of Die Cast Materials

Aluminum alloy 

  • Automotive: lighter in weight, aluminum is an alternative to iron and steel, which are heavier in weight. Its usage has resulted in decreasing fuel consumption and an optimized gearbox shell
  • Aerospace: Its lightweight is the reason aluminum is used to produce aerospace parts.
  • Housing and electric connectors: The products in this industry leverage the high-performance electrical and shielding properties of aluminum.
  • Handheld devices: The shielding properties of aluminum make it apt for devices, as well as its long shelf life and EMI/RFI shielding.
  • Construction: Window frames, curtain railings, partitions, fittings, and cladding use aluminum die-casting products.

Magnesium alloy

  • Automotive: The lightweight magnesium ensures that the product is eventually lighter. This, in turn, increases the speed and efficiency of the vehicle. This property makes magnesium perfect for manufacturing high-performance cars. An example is a sports car.
  • Aerospace: This industry is always on the lookout for materials that are both light in weight and last really long. Zinc fulfills these requirements aptly. 
  • Electronic Casing and Housings: With high conductive abilities, magnesium shields against electromagnetic interference. For the same reason, they are being employed in developing high-quality products such as tablets, smartphones, and TV sets.

Zinc

  • Automotive: It is a hard and strong metal. Therefore it is frequently seen in AC systems, brake systems, and fuel systems. Engine systems and power steering systems also use zinc. 
  • Electrics and electronics: thin walls increase the shielding properties of zinc and improve electrical performance.
  • Complicated products: For any industry that needs complex products, zinc is just ideal as it can be cast easily.
  • Consumer and electrical parts: Consumer products like sink faucets, compressor pistons, connector rods, heat sinks, etc., can be made using high-quality consumer and electrical parts. 
  • Furniture industry: Die casting is often used to prepare furniture components such as knobs and drawer pulls.

Tin 

Generally, tin is used to prepare jewelry and decorative items, but it can also be used to make household appliances. Also, since it is non-toxic, it works well for equipment that is used to store food.

Bronze

It looks like white gold and stainless steel alloy, and the jewelry industry uses it as the die cast material due to its low melting point.

Apart from this, there are many industries that use die casting materials for producing high-quality products that are also durable. 

Cost of die-casting

Generally, die casting works for large-scale production, and the cost may range somewhere between $50000 to $60000. This high cost can be attributed to many factors. Let’s discuss them one by one. 

Factors Affecting the Cost of Die Casting

During the Production

Material

The cost of the material is a key factor in determining the overall cost of die casting. One, the price of the metal can vary depending on how easy it is to get it and how it appears physically. Other determinants include its recyclability and finishing required post-casting. Although 90-95% of waste is utilized, the material waste is also counted.

Machine

As we have already discussed, there are two types of machines used in making die-cast molds: hot chamber and cold chamber. Out of the two, the hot chamber is less expensive than the die-cast machine of the cold chamber. However, the former has a few limitations, and your choice should depend on your final requirement. 

Complexity in design

The more intricacies you need, the higher the cost of die-casting. Some examples of these design requirements include undercuts, high tolerances, and thin walls. 

Production Volume

Simply put, the higher the volume, the higher the cost. Large-scale production will require more materials and tools and hence the cost will be high.

Tooling and molding

You would need tools to do die-casting and will also have to spend money on operating these. Not only this, but their maintenance comes at a price. These additional costs increase the cost of getting die casting on a metal.

Labor cost

Apart from the above, quality assurance (a process that helps establish the product’s quality post-production), packing, and dispatching require labor. Sometimes, post-processing procedures like tapping, CNC machining, anodizing, and drilling are also required, adding up to the gross cost.

Post-production

Not just the above, the following too are taken into consideration when deciding the cost of a die-cast mold:

Design fee

It is usually 2-3 % of the total fee. This comprises 2D or 3D drawings, CNC structures, CAM programming, and CAE mold flow analysis.

Material cost

The main factors that affect the material costs in mold making are the core and frame costs. Frames are either standard or custom-made. Generally, the manufacturers buy the base material from outside. Note that the size of the mold base is dependent on its tonnage. Therefore, the frame material is chosen based on how long the mold is expected to last. An example of this can be aluminum mold, whose shelf life is 80,000 to 100,000 mold times.

Cost of Inspection

Sometimes, inspecting the mold may cost more as it depends on the years of experience and expertise of the technician involved. 

Trial cost

Some alloys require extra safety measures during this phase. An example is magnesium. 

Transportation cost

The cost of die-casting a product is also dependent on the location of the customer. Transportation costs vary due to the weight of the mold. The farther the delivery location, the higher the cost.  

Parting Thoughts 

Manufacturing products with die casting is not easy. It requires precision, especially when the demand is high across industries. But, it is important to know the type of metal to be used. One must also consider the shape of the final product, including its function. Therefore, make sure you side with HiTop Industrial mold designing for your die-casting needs. They use state-of-the-art die-casting machines to provide you with premium quality die-cast products. 

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