Aerospace Casting Process and Advantage
The aerospace industry needs sophisticated parts with the highest quality assurance. Because even a minor defect in a critical component can result in severe consequences, that’s why manufacturers must pay attention to even the smallest details to ensure safety. It would be best if you kept in mind some special considerations when dealing with aerospace casting parts. This article will discuss the suitability of different casting processes and the scope of application for aerospace casting.
Different Casting Process
Aerospace parts are usually large and require high accuracy. And the extreme level of quality control is mandatory for each part produced. So, not all manufacturing techniques are suitable when it comes to aerospace parts. Aerospace parts manufacturing utilizes the following casting processes.
- Die Casting
- Investment Casting
- Sand Casting
We will be discussing the relative and disadvantage of these aerospace casting processes in brief.
Die casting is one of the most popular manufacturing techniques in all industries. And aerospace industry also has a decent application of die cast aerospace parts. It is a cost-effective solution to aerospace casting. Die cast is suitable for manufacturing internal components of aircraft.
It is mainly used for the mass production of certain aerospace parts. Die casting manufacturers can provide a fast turnaround of parts. Thus the production capacity is much greater in this case.
It does have some limitations too. It is only suitable for the production of non-ferrous aerospace parts. And manufacturing of very complex parts may not be feasible or economical.
You may also face issues with the casting quality. Die casting aerospace parts are prone to porosity and other forms of defects without proper quality control. Such defects are not permissible on aerospace parts. So, you have to ensure strict quality control for die casting aerospace parts.
Investment casting is a widely used technique for casting aerospace parts. It is possible to manufacture parts of almost any shape regardless of the complexity. This is crucial for some complex aerospace parts, for example, a turbine. Such parts are complicated to die cast due to their geometry. It is more convenient to machine the parts.
Now, machining a large number of complex parts would not be economical. Investment casting is a viable alternative for aerospace parts in this case. It offers excellent precision with a high-quality surface finish. It is also convenient to cast parts with thin walls.
Investment casting is generally more expensive than other processes. as it requires a lot of preparation. Suppliers will be using disposable wax models for the Investment Casting of aerospace parts. And then apply refractory material coating on the wax models, which hardens and assumes the wax model’s shape. Producers need to melt the wax model and pour molten metal inside the cavity.
When the metal hardens, retrieve the final product by breaking the refractory shell. As you can see, there are too many steps involved, and wastage is high as well. So, investment aerospace casting is generally costlier.
But the supreme quality and strength requirement of aerospace parts are hard to achieve using other processes. Also, note that investment casting is applicable for all types of metals, whether ferrous or non-ferrous.
Sand Casting is the least expensive option for aerospace casting. The mold preparation is easier and way more cost-effective than other processes in case of low volume runs. This type of manufacturing utilizes a special type of sand. The sand is recyclable; thus, there is no material wastage.
The production process is less complicated than investment casting. Also, the size of the casting is not an issue with sand casting. Because sand casting utilizes non-permanent sand mold, which can be of any size and shape, so sand casting can be very economical when you only need a few parts.
However, the casting quality is not as great as that achievable from investment casting. It yields parts with average tolerance and usually has a rough surface. So, it needs more post-processing operations to meet the quality requirements. Also, sand casting aerospace parts may not be the best option for mass-production.
Most of the conventional materials are not suitable for aerospace applications. The parts must be as light as possible yet possess sufficient strength to withstand heavy stress. So, lightweight metal alloys such as aluminum, magnesium, and titanium are more suitable for the job.
We will be discussing the relative advantage and disadvantages of these materials for aerospace casting.
Aluminum is a versatile material for any manufacturing and has a massive application in different industries. The aerospace industry also has a great demand for aluminum die casting. This mainly because of its excellent strength-to-weight ratio.
Aluminum is almost 2.5 times lighter than steel. Iron is generally stronger than aluminum as it has increased density. But, some aluminum alloys have excellent strength properties, and you can engineer the design to carry a similar amount of load possible by a steel part.
So, any aircraft you will come across nowadays mostly consist of aluminum parts. Do note that aluminum is alloyed with other elements to enhance the material properties such as strength and aluminum part’s corrosion resistance.
A7075 is one of the most commonly used alloys for aerospace aluminum casting. It has excellent mechanical strength, ductility, toughness, and corrosion resistance. So, it is a great choice for structural aerospace components. A5052 is another popular aluminum alloy used in aerospace casting. It exhibits better weldability than other alloys.
Magnesium is known for its ultra-lightweight. It is even lighter than aluminum. It makes magnesium an excellent choice for aerospace applications. But, magnesium aerospace castings have limited application compared to aluminum.
Because, apart from its lightweight, it has many deficiencies compared to aluminum. Magnesium is alloyed with other elements to improve its properties. But, magnesium alloy castings are usually softer thus not so stable. They are not suitable for high-stress applications. Yet, it is more expensive than aluminum aerospace casting.
However, magnesium can maintain tighter tolerances, which makes it suitable for aerospace parts with thinner walls. Another advantage is its easy machinability. So, manufacturers are eager to find more applications for magnesium aerospace casting. There is a lot of on-going research on magnesium castings to overcome the drawbacks and unlock their full potential.
RZ5, MSR, ZRE1, etc., are some of the common aerospace magnesium casting alloys. These alloys are great for manufacturing engine housing of aircraft.
Titanium has the highest corrosion resistance and strength-to-weight ratio out of all metals. It is a low-density metal being almost 40% lighter steel. Yet, its mechanical strength is close to that of any high-quality steel. And titanium casting has a very delicate look and feel to it.
That’s why aerospace casting companies prefer titanium over steel. Titanium aerospace castings offer the best quality and durability. It has unmatched structural integrity and toughness compared to both aluminum and magnesium. Manufacturers use titanium for producing sophisticated aircraft components.
But titanium is rarer than other metals. So, titanium aerospace casting is much more expensive. It may not be the most economical option unless you need very high strength and corrosion resistance parts. Also, it is stronger but heavier than aluminum and magnesium.
Ti-6Al-4V is one of the most commonly used titanium alloys in the aerospace industry. It’s lightweight and superior corrosion resistance is a perfect fit for aircraft applications. But, most titanium alloys, including Ti-6Al-4V, has a very low thermal conductivity. It also exhibits poor machinability.
So, it is evident that considering the economic and performance aspects, sometimes aluminum and magnesium may be more suitable and vice versa. It all depends on its application.
Advantage of Cast Components
Aerospace casting has multitudes of benefits over other means of metal-working (i.e., Forging/Forming, Cutting, Joining, etc.). However, none of the processes are redundant. Each process has a specific scope of application. We will mainly discuss the benefits of cast aerospace parts here.
Higher Production Capacity
It is the most amazing thing about casting aerospace parts. Any type of casting technique is significantly faster compared to other means of manufacturing. So, manufacturers can meet large volume production very easily.
Aerospace parts are typically pretty complex, and machining each part for scratch would take forever. Casting is a cost-effective approach for mass-producing aerospace parts. It will always be more economical compared to other metal-working processes.
Manufacturing complex parts has never been easier. In the case of die casting, you create your mold once and create thousands of moderately complex parts. Investment and Sand casting doesn’t have permanent molds, but you can create parts of any size or shape with these processes.
Casting is a convenient way to get parts with a near-net-shape. It offers superior part repeatability. Because each part produced in a batch has consistent quality and precision, one can hardly distinguish one part from another.
Almost all commercially manufactured aircraft components are made by casting. There are endless applications of cast components in the aerospace industry. Some of the typical applications of aerospace casting are as follows.
- Engine Components
- Engine Housing
- Interior Components
- External and Internal Sensors
- Cargo Components
- Landing and Braking Components
- Actuation Systems
- Thin-Walled Sections, etc.
There are many other aerospace applications for cast parts. Those mentioned above are to give you an idea about its scope of use. You can cast any aerospace parts as long as it meets the quality and strength requirements.
Casting vs. Forging Aerospace Parts
Casting aerospace parts involves melting metal and then injecting it inside the die cavity to form the part’s shape. When the casting cools down and solidifies, you can remove it taking the die apart or destroying it. When you are dealing with complex aerospace parts, you will need casting.
Cast aerospace parts are usually lighter than forged parts. And secondary machining requirements are less. But, cast parts are prone to defect unless you ensure strict quality control measures. Also, there is some extent of porosity present in parts. Due to these facts, cast parts have low mechanical strength than forged ones. So, it is best suited for lightweight applications.
Forging aerospace parts involves using compressive forces to shape a metal block or billet into the desired shape. First, you have to heat the metal under a very high temperature. Then apply compressive force by hammering and rolling the billet.
Due to being subjected to extreme stress levels, forged parts are denser and heavier than cast parts. The forged part’s mechanical strength is also higher. However, it is difficult to produce complex parts by forging. Forged parts will need a lot of secondary machining to obtain the desired shape.
If a cast part can meet the strength requirement, then opting for forged parts will not be economical. Plus, lighter parts are preferable for any aerospace application.
Contact Sunrise Metal
Aerospace Casting needs extreme quality control. There is no room for compromises. The price paid for a defective component will be fatal. So, it is of prime importance to choose a qualified aerospace casting company.
Sunrise Metal is a die casting manufacturer with more than ten years of experience in the industry. Our superior quality management has earned us ISO9001 and IATF16949 certification. You can contact us if you need premium die casting solutions. We can ensure optimum quality, competitive pricing, fast turnaround for your parts.