The aerospace sector is quite a demanding one. One must meticulously evaluate the properties of CNC machining materials before using them to ensure safety and reliability. With a wide range of materials available, choosing the most appropriate one can be a daunting task even for professionals.
You must consider several factors from strength and weight to ductility and cost. This article will provide a step-by-step guide for the material selection process of aerospace parts, key considerations to keep in mind, and common examples of aerospace-grade materials and their applications.
Key Considerations for CNC Machining Materials for Aerospace Parts
The wide range of materials available in CNC machining makes it tricky when choose the best. The following factors can be your starting point when selecting CNC materials for aerospace parts.
- Strength
Strength is an important factor when selecting materials for aerospace part manufacturing. It covers everything including tensile strength, yield strength, fatigue strength, and impact strength. From taking off to landing, aerospace material must be able to resist impact and withstand extreme conditions. This guarantees the safety of the passengers and cargo. Note that there should be a balance between strength and weight. Go for materials with an excellent strength-to-weight ratio to improve fuel efficiency and aircraft performance.
- Ductility
Ductility is the ability of a material to undergo plastic deformation without breaking in response to stress. You must factor in ductility during your selection process. Using highly ductile materials for aerospace parts prevents sudden breakdown because the parts will deform in a controlled manner under stress. This property is important for components such as landing gears, wings, and fuselages where small cracks can jeopardize safety.
- Machinability
You also have to consider how easy it is to cut and shape the material to produce accurate and high-quality parts. Prioritize machinability, especially for components with complex shapes and geometries. Easily machinable materials save cost as they require less time and effort to process. Furthermore, they prevent tool wear and reduce frequent replacement. Additionally, the final parts have a greater tendency to meet specified tolerances in the aerospace industry.
- Corrosion Resistance
Consider how well the material behaves when exposed to various corrosive environments such as moisture and chemicals. Parts including fuel systems and engine components are in prolonged contact with corrosive agents. Using suboptimal materials when manufacturing them can lead to failure. Furthermore, you should consider the tendency of galvanic corrosion to occur when using two dissimilar metals together.
- Surface Finish Quality
You also have to keep in mind aesthetics and cosmetic factors. Parts with rough and matte finishes can trap moisture, debris, and dirt when exposed to demanding environments. Note that the level of surface finish quality differs from material to material. Materials that produce continuous chips give parts a better finish. Conversely, parts manufactured from materials whose chips are irregular and discontinuous have a rough finish.
- Dimensional Stability
You should also consider the ability of the material to withstand its shape and size over time. This is particularly important for parts that need to fit precisely during assembly. The material should have a low coefficient of thermal expansion. The dimensions of the final parts will not change significantly when exposed to extreme temperature variations. Furthermore, check if the material tends to absorb moisture which can lead to dimensional changes.
- Electrical Factors
Electrical factors including electrical conductivity and dielectric strength should influence the decision-making process. Check for how well the metal allows the free flow of electricity when manufacturing connectors and wiring systems. For applications where the electric current will affect functionality, ensure you use a material that provides sufficient insulation. Additionally, check for the dielectric strength of the material for parts constantly exposed to high voltage and electricity.
- Material Costs
You should also consider cost when selecting material for aerospace parts. The cost should include the raw material itself, processing, and the ease of recycling. Metals are usually more expensive to purchase than plastics. Within metals, you will see some variations. Furthermore, factor in the processing and operating costs. Materials that are easy to machine cost less per hour when compared to hard ones. Additionally, you should check for how easy it is to recycle or dispose of the materials when selecting the best.
Material Selection Process for Aerospace Parts
To make the selection process easier for you, there are some steps you should take. Follow the steps below when choosing materials for aerospace parts.
- Define Part Requirements
The first step is to define your project requirements. Write down things like the primary function of the parts, what mechanical properties you need, and conditions to which the parts may be exposed. Furthermore, you should also define the required weight of the final part, the tolerance limit, and how easily you can work on the material. It is at this point you decide on the total budget for material procurement and processing.
- Evaluate Material Properties
After stating the requirements of your project, write down the potential materials you will go with. Thereafter, evaluate the materials based on their properties. Find out their strength, hardness level, thermal conductivity, and resistance to impact. Furthermore, you should also evaluate chemical resistance properties, density, and compatibility with other materials.
- Review Material Certification and Compliance
Once you have narrowed down your options, review the materials and ensure they meet all necessary certifications and standards. Make sure the materials conform to requirements set by the Aerospace Material Specifications (AMS) and International Organization of Standardization (ISO). They should also comply with international regulations and should not produce hazardous fumes when you are working on them.
- Consult with Material Suppliers
Now, it is time to contact the material suppliers and discuss all your needs. Reach out to suppliers that provide aerospace-grade metals and plastics. Tell them your project requirements and relevant factors. You can contact as many suppliers as possible to be sure you get to work with the best. Negotiate pricing and delivery terms and be sure everyone is on the same page.
- Make your Decision
After gathering all the necessary information, make a final decision on your material. Writing down the pros and cons of each material may help streamline the decision process. You should also conduct a cost-benefit analysis to determine the material that may be the best for your project. Communicate your decision to relevant stakeholders and move on to the next step in CNC machining of aerospace parts.
Common Materials Used in Aerospace CNC Machining
There are many materials you can use in aerospace CNC machining. Each material has its unique advantages and capabilities. Let’s look at the most common materials suitable for manufacturing aerospace parts using the CNC machining technique.
- Aluminum Alloys
Aluminum alloys are one of the most popular materials employed when manufacturing aerospace components. There are many aerospace grade aluminum alloys available with the most common being 2024, 6061, and 7075. They all have a remarkable strength-to-weight ratio. This implies that you build sturdy parts while reducing fuel usage at the same time. Furthermore, aluminum alloys are corrosion-resistant and thermally conductive. You will find them in engine components, wheel hubs, and fasteners.
- Titanium
Titanium is another metal you can use for aerospace parts. This metal is stronger than most aluminum alloys and resists impact efficiently. Furthermore, it is ductile and does not break when used in demanding situations. The lustrous and appealing appearance of titanium makes it suitable for external aircraft components. However, this metal has limited electrical and thermal conductivity. Also, CNC machining titanium requires expertise and specialized tools because this metal may be difficult to work on.
- Stainless Steel
There are different categories of stainless steel alloys you can use when CNC machining aerospace parts. Examples of suitable alloys include 17-4 PH, 440C, and 410. Stainless steel has applications when manufacturing aircraft hardware such as bearings, bushings, heat exchangers, and exhaust systems. These parts are resistant to wear and easy to clean. Additionally, they are highly durable and you don’t have to replace them often.
- Nickel-Based Alloys
Nickel-based alloys are another type of material suitable for machining aerospace parts. Common forms of this alloy include Inconel 718 and Haynes 230. Inconel 718 has remarkable mechanical strength and is suitable for high-temperature environments such as gas turbines and engine components. Furthermore, Haynes 230 is corrosion-resistant and durable. You can use this alloy when manufacturing heat exchangers and other demanding aircraft parts.
- Plastics
You can also use different plastics and polymers when manufacturing specific aerospace components. Most plastics are less dense than metals and still perform excellently well. Plastics including HDPE, nylon, PEEK, PC, and acrylic are good substitutes for metals. They are electrically insulating, impact-resistant, and nonmagnetic. These plastic materials are suitable when producing trims, panels, pipes, and heat shields.
- Composites
Composites especially fiber-reinforced polymers have applications in the aerospace industry because of their many properties. They have a high strength-to-weight ratio and are not susceptible to corrosive attack. Furthermore, composites have superior fatigue resistance properties and you can easily work on them to create high-quality parts with detailed features such as wing spars and ribs. Note that when machining composites you have to use an adequate cooling system to prevent overheating.
Conclusion
Selecting the right precision CNC machining material for aerospace parts is a critical decision. You need to carefully consider several factors before making your choice. The decision should be guided by a thorough understanding of the material properties and cost-effectiveness. By carefully evaluating these factors and aligning them with your project requirements, you can be sure of manufacturing parts that meet the demands of the aerospace industry.
