Die casting is an important part of the automotive industry because it forms the majority of car spare parts. But what is die-casting? There are many explanations that you can find on the Internet, but the essence of the die-casting process is actually pouring molten metal with a low melting point into a mold and then cooling it.
It’s basically “an ancient technology” but still effective as of this writing. Die casting manufacturers usually two types of casting; hot and cold chamber casting. The molds used are usually made by a CNC process so details are accurate. The casting is commonly used to produce sheet metal.
Perhaps the most striking advantage of die casting is that it is highly effective in the production of stronger as well as thinner auto parts. That’s why increasingly modern die-casting processes have contributed to the weight loss of cars in recent decades.
Material Requirements for Die Casting in Automotive Applications
In general, there are several factors to consider when choosing the right metal.
Mechanical properties which include:
Thermal properties which include:
- Thermal conductivity
- Thermal expansion
– Corrosion resistance
– Resistance to fatigue
– Lightweighting considerations.
Common Materials Used in Die Casting for Automotive Applications
To be noted, casting parts in automobile can accommodate a variety of metals, especially those that are not based on iron. However, there are always favorite metals. There are three most commonly used; aluminum, magnesium, and zinc.
We will discuss in general terms how each of them is reviewed based on their advantages and properties. Of course, they are not used in their pure form. The items listed below are therefore referred to as alloys.
Advantages: Perhaps the most popular advantage of aluminum alloy is its lightness. The lighter the overall parts in a car, the lighter the car and the more efficient the car is in terms of fuel consumption. Aluminum also tends to be easily formed so that it accommodates even complex designs. And to add, aluminum is relatively more heat resistant, friction resistant, rust resistant, and easy to recycle so it is environmentally friendly.
Properties: Aluminum has unique properties such as being non-toxic, a good heat conductor, high strength-to-weight ratio, being relatively corrosion resistant (as long as there is no oxidation process), having uniform quality, and being easy to form.
The aluminum alloy die-casting process typically targets parts such as hydraulic cylinders, valve bodies, gears, and engine brackets.
Advantages: There are many magnesium alloys available in the market, providing more specific advantages for different industries. Common favorite alloys are AM60B, AZ91D, AZ81, and AS41B. But whatever the type of alloy, in general magnesium offers toughness. That is why the metal is used more in parts where toughness is more important than deformation.
Properties: Magnesium has beneficial properties such as being very lightweight (the lightest of the metals commonly used as car parts), can be recycled 100%, high strength-to-weight ratio, and having very good dimensional stability.
Magnesium is very light and strong, so it is commonly used in the manufacture of gearbox casings, brake housings, and drive shafts.
Advantages: Zinc die casting is preferred because of its highest tolerance compared to other metals. It is accurate, therefore very competitive. Zinc die casting tends to be cheaper than other metals. Another interesting thing is that zinc die casting tends to produce small draft angles which is an advantage during the mechanical process.
Properties: The ability to harden faster after melting, a relatively higher level of hardness than other metals, and the ability to conduct heat very well.
Automotive applications and considerations: There are many applications of zinc alloy die casting in the automotive world and to mention a few, it is used to manufacture power steering systems, fuel systems, certain components of brake systems, some engine parts, and components of car air conditioning systems. The consideration in using zinc alloy is that it is accurate to be accommodating complex shapes.
Material Selection Process
The selection of metal materials for die casting must meet several requirements, for example:
- Design requirements and constraints.
- Material testing and analysis.
- Performance requirements and trade-offs.
- Collaboration with material suppliers.
Why? Because die casting is for different industries and design requirements result in “different hires”. Constraints are also decisive because the need for certain parts usually does not allow for certain metals. For example, engine components that are often subjected to consistently large loads are not recommended to use zinc.
Performance requirements and trade-offs are ultimately taken into consideration to decide on the substitution of metal A for metal B (if metal supplies are limited). And to add, the collaboration with the metal material provider is what defines how the proposal content will be. If you can’t find a provider for a particular metal, no matter how good it is, it’s likely not going to fit into the plan.
The conclusion that can be drawn is that die casting is a crucial process in any automotive industry and the three types of metals above seem to be the most widely used due to their advantages and properties. And finally, considerations such as the desired design, production limitations, the need for certain properties in automotive components, and the availability of metal material providers are the determinants of choosing a metal as a die-casting object.