2025/02/20 015｜Aviation Development and Manufacturing

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015｜Parts Technology in the Aviation Industry

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1. History of the development of the aviation industry

If we look at the appearance of modern aircraft and the history of the aviation industry, we can trace it back to the invention of the hot air balloon in the late 18th century and Otto Lilienthal, the German glider king. This not only affected people's views on aircraft from the late 19th century to the early 20th century, but the subsequent unexpected news also rekindled the childhood dreams of the Wright brothers. So in 1903, after the Wright brothers successfully tested the first powered aircraft, the era of modern aviation was officially opened. Subsequently, the two world wars promoted the rapid development of aviation technology, and the application of jet engines and lightweight materials greatly improved aircraft performance. In addition, people gradually became aware of aviation regulations such as flight safety and laws. To this day, aviation development continues to improve and new technologies are invented.

In aircraft manufacturing, with the progress of industry, from early industrial technology to the later development of lathes, end mills, CNC technology, or the processing evolution of titanium alloys, carbon fiber composite materials, etc. in the field of materials, or the later derived "selection" of cutting tools and CNC equipment, as well as the focus on the scope between production costs and production efficiency, etc., whether from the technical aspect, material aspect or operation and management aspect, these are all related to the production of take-off and landing equipment, power equipment, fuselage, wings, tail, interior and other components, each of which plays a very important core role.

The manufacturing process of aircraft is also accelerating due to high-efficiency tools, modular manufacturing, and automated production, which includes stable and precise production requirements. Of course, compliance with flight specifications is also essential. Then, in modern times, after entering the digital and AI era, AI control, 3D printing, and intelligent tool management will be further applied in the future to improve production efficiency in the aviation field. The models of this article are mainly civil aircraft. Civil aircraft are highly precise industrial manufacturing. The industrial revolution and modern technology have greatly advanced aircraft manufacturing technology. The birth of different aircraft has also made the modern aviation field present a colorful appearance.
 

2. Aircraft Manufacturing and Precision Machining Technology

Aircraft manufacturing involves complex engineering design and high-precision manufacturing technology, mainly including fuselage structure, engine, landing gear and internal system. Modern aircraft mainly use high-strength aluminum alloy, titanium alloy and carbon fiber composite materials as the main body to ensure lightweight and high strength requirements, and then use CNC technology to manufacture aircraft parts, and use computers to control lathes and milling machines to achieve micron-level precision in parts manufacturing. End mills are the most important tool members in CNC machining and are widely used in processing aluminum alloys, titanium alloys and composite materials.

Before introducing the processing, The following is divided into several common parts of the aircraft for explanation -



⚫ 1. Aircraft landing gear
Landing gear refers to the key structure of an aircraft during takeoff, landing and ground taxiing. Its main function is to support the weight of the aircraft, absorb shock and provide reliable stability. In order to facilitate this system, it is usually composed of several parts, including the main landing gear (MLG) to support the main weight of the aircraft, and the nose landing gear (NLG) which is often located at the nose and provides direction and support for the aircraft. The shock absorbers are also called dampers and shock absorbers. They are important devices that can absorb impact force. There is also a braking system (Braking System) that improves the "braking force". It is usually based on carbon fiber or steel brake discs. By the way, there are three common braking modes in aircraft takeoff and landing.
 

	Main Mode	Device function
Engine thrust reverser	Power brake	Braking assistance
Spoiler on top of wing	Pneumatic brake	Braking assistance
Main landing gear brake system	Hydraulic brake	Main braking methods

Finally, there is the retractable system, which is foldable in design and controlled by hydraulic or electric mechanisms to reduce flight resistance and ensure safe landing. For small aircraft, light aircraft, traditional aircraft, etc., fixed take-off and landing devices are mainly used. Here's an interesting topic. If it's an aircraft that takes off and lands on snow, it's often found that the design concept is sleds, while seaplanes are designed with float-type landing gear. These differences, which are adapted to local conditions, also show different "flight conditions" and application modes.



⚫ 2. The main power unit of the aircraft
The power unit of an aircraft can determine its flight performance and range. From early propeller engines to modern turbojet engines, technology has developed extremely rapidly. In terms of contemporary design, there are three main types of aircraft power units, namely propeller engines, jet engines, and future power technology. The engine materials are often based on titanium alloys, nickel-based alloys, ceramic composites, carbon fiber composites, etc.

Common propeller engines include piston engines (Piston Engines) such as the Cessna 172 light aircraft, and turboprop engines (Turboprop Engines) such as the ATR 72 passenger aircraft. Jet engines (Jet Engines) have turbojets as their core, such as the early F-104 Starfighter, and turbofan engines (Turbofan Engines) as their power, such as the Boeing 747. This engine is not only highly efficient and low in noise, but is also a common engine type for current passenger aircraft. There are also turboshaft engines (Turboshaft Engines) such as the Black Hawk helicopter, which can provide stable rotor power.

Future Propulsion Technologies include electric power, hydrogen fuel, scramjet and other power technologies. For example, electric aircraft uses batteries and electric motors, which is very suitable for short-distance flights. It is still under development and will be a trend, especially in the face of issues such as environmental protection and carbon tax. Hydrogen fuel and hybrid power can also reduce emissions and increase endurance. There are also supersonic and scramjet engines, which are new power systems used by military aircraft and space vehicles. These are all expected power development directions in the future.



⚫ 3. Body
The fuselage (Fuselage) comes from the French word "fuselé", which means spindle-shaped. It is the main structure of the aircraft, responsible for carrying passengers, cargo, fuel, flight control systems, engines and other equipment. It is also an important component for bearing various forces during flight. The fuselage design emphasizes lightness, durability, and aerodynamic efficiency while ensuring safety and comfort. The fuselage can be divided into several parts, such as the front fuselage, middle fuselage, rear fuselage, skin appearance and frame. Common materials are aluminum alloy, carbon fiber composite materials, titanium alloy, glass composite materials, etc., among which composite materials are more common in recent years.

A good fuselage design also needs to meet the following common conditions. The first is aerodynamic design to improve flight efficiency, while the internal structure design affects the cabin's bearing capacity, as well as the configuration of cargo holds and fuel tanks. Of course, safety design is definitely the most important, requiring various safety considerations such as impact resistance and fatigue resistance. There are also fuselage designs that use honeycomb structures, which not only enhance toughness but also make the aircraft lighter, helping to improve fuel efficiency.

There are still many possibilities for the development of fuselage manufacturing in the future. For example, 3D printing technology (Additive Manufacturing) is used to manufacture composite parts, which not only improves efficiency but also reduces material waste. There are also robotic assembly robots that can perform high-precision welding and assembly. This method can improve consistency and stability of quality management. There is also the development of intelligent material applications, research on deformable fuselage structures, improved aerodynamics and fuel efficiency, and improved efficiency of various types of power.



⚫ 4. Wing
The wings are generally located on the left and right sides and the tail. They are important devices that provide lift for the aircraft. They are composed of ailerons, flaps, slats, wingtip winglets and other structures. They make the aircraft take off through the principles of fluid mechanics. In addition to controlling lift, modern wings also carry fuel, landing gear and some airborne electronic equipment. The following will introduce the composition of the wing one by one.

First of all, the main function of the leading edges of the left and right wings is to affect the flow of air. When the aircraft is moving, the airflow first contacts the leading edge of the wing and begins to separate from it. Some wing designs are equipped with anti-icing systems to combat routes and areas with extreme climates. Next is the trailing edge of the wing, which is located at the tail end and includes ailerons, flaps, etc., which can affect the aircraft's maneuverability and lift adjustment. Then there is the design of the wing beam, which is also called the wing skeleton. It is used to withstand flight stress, as well as the outer shell covering the wing and the internal design of the wing. Many aircraft also design the interior of the wing as a fuel tank to reduce the weight of the fuselage and optimize the configuration.

In terms of manufacturing, wings are not necessarily considered the most difficult part of an aircraft to manufacture. However, due to their large size, they require a large, wide horizontal processing environment and several days to complete. The details of the wing have different processing applications. For example, the wing ribs have thin walls and 2D grooves, which are processing challenges. Therefore, it is important to use a good milling cutter. In particular, the lightweight groove design requires a faster and more efficient processing method to reduce costs when 90% of the workpiece material will be removed in the form of chips. The processing conditions of the thin-walled part will vary according to the wall height and thickness, and the number of passes is determined by the wall size and axial cutting depth.



⚫ 5. Tail
Finally, there is the tail part. Although it does not provide power itself, it also plays an important role in working with the flight system. It is generally divided into two designs: the horizontal tail (Horizontal Stabilizer) and the vertical tail (Vertical Stabilizer). The horizontal tail has an elevator to control up or down, while the vertical tail has a rudder to control left or right. The material design is similar to that of most devices and are made of materials with low resistance, lightness and strength, including aluminum alloy, carbon fiber, composite materials, titanium alloy, etc. They must not only be durable and lightweight, but also resistant to high temperatures and impact, etc.

Regarding the integration of the wing parts using a table:

Location	Function	Material	Related dynamics
Wing	Generates lift, stores fuel, affects flight control and carries the fuselage	Carbon fiber composite materials, aluminum alloys, titanium alloys, magnesium alloys, nickel alloys, etc. Composite materials have become a trend in recent years.	Pneumatic, fly-by-wire, fuel
Rear	Divided into horizontal tail and vertical tail, each with different control directions and functions		Electromechanical system, hydraulic control

The design trend of modern aircraft wings and tails is to reduce weight, increase rigidity and enhance aerodynamic efficiency, and to improve aircraft performance and fuel efficiency through advanced materials (such as carbon fiber) and digital control technologies (such as fly-by-wire flight control).
 

3. Technology and application of end mills

End mills are precision tools used for milling. They are suitable for machining 2D and 3D shapes, such as contour milling, groove machining and surface machining. There are many articles on end mills. This article will focus on the aviation industry. Currently, there are the following applications:

◼Aluminum alloy parts processing: Aluminum alloy has good machinability and good plasticity. High-speed carbide end mills are usually used to improve processing efficiency.

◼Titanium alloy parts processing: Titanium alloy has high strength and corrosion resistance, but it is difficult to process. Specially designed wear-resistant end mills are usually used to improve cutting performance.

◼ Carbon fiber composite material processing: Due to the anisotropy and layered structure of carbon fiber materials, end mills with special coatings and geometric designs are required to reduce delamination and burrs.

◼Civil aircraft parts manufacturing:
    ☐ Instrument Panel: Instrument panels are typically made of aluminum alloy or composite materials and are precision machined using micro end mills to ensure precise alignment of buttons and displays.
    ☐ Wing: Both the internal support structure and the external skin of the wing require high-precision processing, using high-speed aluminum alloy-specific end mills to achieve ideal finish and rigidity.
    ☐ Cockpit interior parts: such as cockpit control levers and instrument panel frames, are usually processed by high-wear-resistant end mills to improve service life and safety.

[1.] Application of CNC and end mills in aviation industry manufacturing
Modern aircraft manufacturing is highly dependent on CNC (CNC machine tool) technology, especially in high-precision parts processing, structural parts manufacturing and mold manufacturing. End mills are the core cutting tools for CNC processing. The following are the application ranges: (Note: The accuracy of CNC processing can reach ±0.01mm, ensuring the high consistency and safety of aircraft parts)



[2.] Application of processing molds in aviation manufacturing

☐ Assembly Jig: Fixes large parts such as the fuselage and wings to ensure assembly accuracy.
☐ Stamping Die: Used to manufacture aluminum alloy skins and internal structural parts.
☐ Carbon fiber molding mold (Composite Mold): Used to make carbon fiber parts of the fuselage and wings to ensure shape and strength.

[3.] The role of CNC milling in mold manufacturing
☐ High Speed ​​Machining (HSM) improves mold processing efficiency and shortens production time.
☐ Multi-axis CNC (5-axis CNC) accurately processes complex surfaces and improves mold quality.
☐ Wear-resistant tools (CBN/PCD milling cutters) increase the processing life of carbon fiber and titanium alloy.

[4.] Matters needing attention during processing
Aircraft parts processing must ensure high precision, high quality and safety. Common considerations include - 

(1) Material properties affect processing
☐ Carbon fiber composite materials: PCD milling cutters are required to avoid overheating and deformation of the material.
☐ Titanium alloy: Low speed and high torque cutting are required to prevent tool overheating and wear.

(2) CNC processing technology
☐ Multi-axis CNC (5-axis): Reduce clamping times and improve machining accuracy.
☐ High speed cutting (HSM): Improve efficiency, but cutting heat needs to be controlled.

(3) Tool selection and maintenance
☐ Coated tools (TiAlN, DLC) extend tool life and reduce tool change time.
☐ Tool cooling (MQL, cold air cooling) reduces temperature and improves processing quality.

(4) Quality Control
Non-destructive testing (X-ray, ultrasonic testing): Check for internal defects.
Precision measurement (CMM, laser scanning): ensure tolerances meet standards (±0.01mm)

4. End mill material and application range

The material selection of the end mill depends on the processing materials and requirements, mainly including:
◼ Carbide :
Suitable for aluminum alloys, titanium alloys and composite materials, with high wear resistance and long life.
◼ High-speed steel (HSS) :
Suitable for materials with lower hardness, such as general aviation aluminum, with lower cost but lower wear resistance.
◼ Polycrystalline diamond (PCD) :
Suitable for carbon fiber and high wear-resistant materials, can reduce burrs and extend tool life.
◼ Cubic boron nitride (CBN) :
Mainly used for precision machining of high hardness materials, such as titanium alloys and nickel-based alloys.

[1.] Cost considerations:
Aircraft manufacturing costs are extremely high, and the main factors affecting this are:
◼Material cost:
Titanium alloy and carbon fiber are expensive, accounting for 20-30%.
◼CNC machining and tool costs:
☐ High-hardness materials (such as titanium alloys) require special tools (PCD/CBN), which are more expensive.
☐ High-speed cutting and multi-axis machining equipment are expensive, but can improve efficiency.
◼R&D and testing:
☐ Aircraft parts must pass rigorous testing (fatigue testing, strength testing), and the development cost is high.
☐ Quality inspection (CMM, X-ray inspection) ensures that parts are defect-free and increases costs.

[2.] Methods to reduce costs:
◼Additive manufacturing (3D printing):
Reduce material waste and improve manufacturing efficiency.
◼Tool optimization (high-performance milling cutter):
Use multi-edge tools and wear-resistant coatings to reduce tool consumption.
◼Automated production:
Improve the automation level of CNC machining centers and reduce labor costs.

[3.] Manufacturing schedule:
The complete manufacturing process of a civil aircraft includes design, parts processing, assembly and testing, which usually takes 9 months to 3 years, depending on the model and production volume. The following is a rough distribution of production time (for reference only):

Stage	Time／Schedule
Design and development	1-3 years (new model development)
Parts production	6-12 months
Fuselage and wing assembly	3-6 months
Engine installation, interior assembly	3-4 months
Testing and Certification	6-12 months

Modern trends, such as Boeing 787, Airbus A350 and other models are mainly based on "modular manufacturing", that is, the global supply chain produces different parts simultaneously, which speeds up the assembly process. On average, an aircraft is completed in about 9-12 months. Aircraft manufacturing is often based on aluminum alloys, carbon fiber composites and titanium alloys. Aerodynamics, structural strength and safety must be taken into account during design. CNC precision machining and end milling cutter technology in the process are also crucial to ensure the accuracy and durability of fuselage parts. With the development of technology, the future will be towards lightweight, intelligent and automated development to improve aircraft performance and achieve environmental friendliness.
 

5. Future Development of End Mill Technology

The development of the aviation industry depends on the advancement of precision manufacturing technology, and end mills, as core cutting tools, play a key role in improving the manufacturing accuracy and efficiency of aircraft parts. In the future, with the development of intelligent manufacturing and new material technology, end mills will continue to provide support for innovation in the aviation industry. As the aerospace industry's requirements for precision and efficiency continue to increase, end mill technology is also continuing to innovate, such as:

◼Ultra-hard material tools (such as PCD and CBN tools) improve wear resistance and life.
◼Smart tools are equipped with sensors for real-time monitoring to improve processing stability.
◼High-speed machining technology, combined with optimized tool geometry and coating, improves machining efficiency.

Additional explanation - What is lift?

Lift is the key force that enables an aircraft to fly. It is an aerodynamic force that acts upward, counteracting gravity and allowing the aircraft to take off. When the wing moves forward, air passes over and under the wing. Due to Bernoulli's principle, the airflow above the wing is faster and has a lower pressure, while the airflow below is slower and has a higher pressure, generating lift. In addition, Newton's third law (action and reaction) also plays a role. The wing pushes the airflow downward, and the reaction force of the air pushes the aircraft upward. The aircraft's angle of attack, speed and wing design all affect the size of the lift.
 

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