Machining Aerospace Parts

In 1992, a routine training mission for an F-16 fighter jet took a dramatic turn. The plane, fortunately, crashed in an unpopulated area with no casualties. However, the investigation revealed a culprit: a seemingly insignificant pin inside the engine. This pin, part of a mechanism controlling airflow within the engine, fractured due to metal fatigue.

The failure of this small, machined part caused the entire engine to fail, jeopardizing the pilot and potentially putting lives on the ground at risk. This incident serves as a stark reminder of the critical role machined parts play in aerospace. Within each of its applications in the aerospace industry, CNC machining is an often overlooked key player. Every component, from the engine housing to the landing gear, needs to be meticulously crafted to withstand extreme stresses and environmental conditions.

Applications of Aerospace CNC Machining

CNC machining is an often sought after service in manufacturing custom aerospace components for numerous applications in the industry. From complex designs to standard screws, the assembly of aerospace products and machines would not function without it. 

1. Aerospace Component Manufacturing:
   • Aircraft Structural Parts: CNC machining is used to produce critical structural components such as fuselage frames, wing spars, and landing gear parts. These components require high precision and strength to withstand the stresses of flight.
   • Engine Components: Aerospace machinists and precision machining are essential for manufacturing complex engine parts like turbine blades, housings, and fuel system components. These parts must endure high temperatures and pressures.
   • Avionics Housings: Machining aerospace parts creates precise enclosures for avionics systems, ensuring the protection and functionality of sensitive electronic components.
   • Interior Components: It is used for producing interior parts such as seat frames, overhead bins, and tray tables, focusing on both durability and aesthetic quality.
2. Tooling and Fixtures:
   • Assembly Fixtures: Machining custom fixtures for assembling various aircraft components ensures accuracy and repeatability in the assembly process.
   • Inspection Tools: CNC machines produce precise gauges and measurement tools that are used to verify the dimensions and quality of aerospace parts.
3. Prototyping and Testing:
   • Rapid Prototyping: CNC machining is utilized for creating prototypes quickly, allowing for the testing and refinement of designs before mass production.
   • Wind Tunnel Models: Scaled models for aerodynamic testing in wind tunnels are often machined to exact specifications to study airflow and performance characteristics.
4. Maintenance, Repair, and Overhaul:
   • Replacement Parts: Machining aerospace parts produces high-quality replacement parts for aircraft maintenance and repair.
   • Tooling for MRO: Custom tools and fixtures for maintenance operations are often machined to ensure precision and reliability.

Materials Used in Aerospace CNC Machining

Common materials used in aerospace components include aluminum, titanium, stainless steel, nickel, carbon fiber, ceramics, and more. Each of these materials offers strengths and weaknesses for aerospace machinists to weigh. 

1. Metals:
   • Aluminum Alloys: Widely used for their high strength-to-weight ratio, corrosion resistance, and machinability. Common alloys include 2024, 6061, and 7075.
   • Titanium Alloys: Known for their excellent strength, low weight, and resistance to high temperatures, making them ideal for engine components and structural parts. Titanium 6Al-4V is particularly common.
   • Stainless Steels: Utilized for their corrosion resistance and strength, often in critical components that require durability and resistance to harsh environments.
   • Nickel Alloys (e.g., Inconel): Essential for high-temperature applications such as turbine blades and exhaust systems due to their ability to maintain strength and resist oxidation at high temperatures.
2. Composites:
   • Carbon Fiber Reinforced Polymers (CFRP): Valued for their exceptional strength-to-weight ratio and used extensively in structural components like wings and fuselage sections.
   • Glass Fiber Reinforced Polymers (GFRP): Used in areas where high strength and lightweight characteristics are required, though not as strong as CFRP.
3. Specialty Materials:
   • Ceramics: Employed in specific high-temperature applications such as heat shields and some engine components due to their ability to withstand extreme temperatures and wear.
   • Magnesium Alloys: Used for certain components where reducing weight is crucial, offering a good balance between weight and strength but with some limitations in corrosion resistance.

Machining aerospace parts is integral to manufacturing high-precision, high-strength components essential for aircraft performance and safety. It encompasses a wide range of applications from structural parts to engine components, and utilizes advanced materials like aluminum, titanium, and composite materials to meet the demanding requirements of the aerospace industry. Choosing a trusted aerospace machinist is your duty as a manufacturer.

How is CNC Used in The Aerospace Industry? 

CNC technology has been a key provider of aerospace components over the last 60 years. However, this was not the case early on for the industry. It is hard to mention the history of aerospace without mentioning the Wright Brothers and the historic flight back in 1903. The sustained flight was just a glimpse of what was to become of a very robust industry. The early technology had limitations for an aerospace company back then. The planes were made mostly of wood and fabric. This took the efforts of very skilled craftsmen, time, and ingenuity to produce aircraft parts. These were not what we would call today’s precision aerospace parts, but remarkable, nonetheless in the quality they were able to achieve. As progress was made for better aerodynamics, prolonged flight, and overall performance, it was clear that changes were going to be needed. World War II pushed all industries to create not only better designs of planes, firearms, armor, but also new types of bolts, screws, nuts, fasteners, engines, handles, levers and just about everything you can think of. As new engineering breakthroughs emerged, the growth required new materials to be developed and machined. This era, though tragic, also would propel the world into higher levels of mass production with precision. Without these advances we would not have the level of technology we take so much for granted. When the transition of wood to metals like aluminum took place, this was a societal breakthrough. Not only would all transportation change, but the world economy’s world see growth unlike in any previous millennia. The key was a way to manufacture the needed precision that the advancing aerospace industry would require. CNC technology would be that solution. CNC or computer numeric control are manufacturing methods supporting almost all industries as well as aerospace. This industry has greatly advanced with computer technology and seems to have no limitation when science and industry ask for support. 

CNC technology encompasses multiple methods to produce precision aerospace components. There are three main materials used by the aerospace industry that CNC manufactures process: 

• Aluminum Alloys:  Used widely in aerospace manufacturing. It has an excellent strength-to-weight ratio and machinability. It is used in airframes and other body structures. 
• Titanium Alloys:  Titanium has superior strength and fatigue resistance and is the top choice for high-stress components like landing gear and jet engine parts. 
• Steel Alloys: Steel can be used for engine mounts, and other parts requiring exceptional strength. Steel is heavier than aluminum and titanium so specific needs and cost considerations warrant this material’s use. 

Aerospace machinists will use different methods to manufacture precision parts. Examples of these are:  

• CNC Drilling: Very precise holes for rivets and fuselage panels. For holes in brackets, frames, and engine parts. 
• CNC Turning: CNC turning uses lathes to create cylindrical shapes like axels, shafts, bushings, and pins, landing gear parts and engine components. 
• CNC Threading: Parts manufacturers use threading to properly secure connections and fasten down assembled components and systems. 
• CNC Laser Cutting: Used to cut precision parts that have structural uses like frames and brackets. Versatile in developing R&D parts as well. 
• CNC Waterjet: This technology eliminates ant heat affected zones or HAZ, that can occur with other methods machining aerospace parts. Great for cutting engine components, structural and other complex and critical parts.  

A precision aerospace company will use or work in partnership with qualified CNC technology professionals. The stringent requirements asked for each project are for the public’s safety. Aerospace components are a result of many years of advances in technology, but also advances in science and engineering. As progress is made so does the need to bring new ideas and concepts into reality by a sustained and reliable manufacturing solution such as CNC machining.