Applications of CNC machining in the aerospace industry

An important tool in the aerospace industry is CNC machining. Aerospace machining results in advanced aircraft parts made from lightweight metals such as titanium and aluminum, and machining is also a valuable prototyping tool for aerospace parts.

This article provides an overview of how CNC machining is used in the aerospace industry. It looks at aerospace CNC machining applications, aerospace machining materials, and more.

What is aerospace?

Aerospace is a very diverse industry that encompasses many sub-sectors, including everything from commercial aviation to space exploration. Its value as a global industry. Aerospace manufacturing involves the production of parts for commercial, industrial, and military customers, with governments being some of the largest contractors in the industry.

Due to the large number of aerospace subsectors and the large number of applications and products within those subsectors, aerospace requires a wide range of manufacturing technologies, from traditional techniques like casting and welding to advanced technologies like metal additive manufacturing. Aerospace CNC machining falls somewhere in between those two extremes, being a mature technology but still offering advanced design and materials capabilities.

What is aerospace machining?

Machining is the manufacturing process of removing material from a workpiece using machine-operated cutting tools. And CNC machining is a digital version of machining: computers control motorized cutting tools to form new parts quickly and accurately.

Aerospace CNC machining dates back almost to the invention of CNC machining in 1942. One of the earliest applications of aerospace CNC machining was the production of bulkheads and wing skins. Today, many aerospace components can be machined, such as gearboxes, landing gear, and electrical components. Machining can also be used to repair or modify existing components, to add detailed features, or to add engraved text information such as serial numbers.

Since much aerospace machining involves the production of critical end-use parts, precision machining with high-quality 5-axis machining centers is required. Some components – such as jet engine components – can require tolerances as tight as 4 microns, much tighter than what is typically accepted in CNC machining.

Aerospace machining is also an important form of prototyping during research and development. CNC machines are well suited for prototyping metal aerospace components that will later be manufactured using casting or other techniques.

Aerospace Machining

Aerospace machining is responsible for a wide range of aerospace components, from critical titanium jet engine components to lightweight plastic cabin interiors.

Parts suitable for aerospace CNC machining are typically low-volume parts that require high strength and good features. Such parts are often limited in size by the size of CNC machining centers, but can use a number of different materials, typically titanium or aluminum alloys, but other options such as engineering plastics and composites are also available. Some parts can only be machined after being cast or extruded.

Aerospace machining can be used for prototypes and end-use parts. However, end-use parts must meet strict safety criteria, standards, and certifications.

Machinable Aerospace Parts

• Landing Gear Components
• Turbine Blades and Other Jet Engine Components
• Engine Casings
• Oxygen Generation Systems
• Filter Housings for Liquid and Air Filtration Systems
• Electrical Connectors for Electrical Systems
• Motion Controls
• Actuators
• Fuselage Components
• Wing Ribs
• Disks
• Drive Shafts
• Missile Skins and Other Components
• Cabin Components
• Seats, Armrests, and Trays

Aerospace Machining Materials

CNC machining is a versatile process that can be used to fabricate parts from both metals and plastics. However, in the aerospace industry, two metals in particular reign supreme: titanium and aluminum. This is due to the high strength (especially titanium) and light weight (especially aluminum) of the materials.

Titanium Alloys

No industry worldwide uses more titanium alloys than aerospace. It’s easy to see why: the metal has an excellent strength-to-weight ratio, is corrosion resistant, and performs to a high standard in extreme temperatures. Titanium has become a staple material in aerospace manufacturing, and its use is set to increase even further in the coming century.

Titanium aerospace parts include airframes and jet engine components, such as discs, blades, shafts, and housings. Many of these can be machined.

Because titanium is harder than aluminum, it can be more difficult to CNC, causing tool wear and heat buildup. This means that machining titanium in aerospace can require reduced machine RPMs and higher chip loads. (See our titanium machining guide for more information.) However, since aerospace machining typically involves the most advanced and high-end machining equipment available, this is rarely an issue.

Aluminum Alloys

Another metal that is widely used in aerospace machining - and one that has been around longer than titanium and modern composites - is aluminum.

Aluminum alloys are lightweight and have high tensile strength. Aluminum forms an oxide coating when exposed to air, making it resistant to corrosion, and it is also highly formable (more so than titanium), making it easy to CNC machine.

In aerospace CNC machining, the most common aluminum alloy is 7075 aluminum, the main alloying element of which is zinc. Although not as machinable as other alloys, 7075 has excellent fatigue strength. Many structural components of wings, fuselages, and supports are made from this material.

Other machinable aerospace aluminum alloys include 4047 (coating/filler), 6951 (fins), and 6063 (structural). The 6000-series alloys are generally considered to be easier to machine than other alloys.

High Performance Plastics

In addition to metals such as titanium and aluminum, aerospace machining may involve the use of high performance plastics such as PEEK, polycarbonate, and Ultem.

Plastics can be useful substitutes for metals due to their extremely light weight, good impact and vibration resistance, sealing properties, and chemical resistance. They also provide superior electrical insulation to metals.

Aerospace CNC machining of engineering plastics can produce aerospace components such as cabin interiors, tray tables, armrests, housings, abrasion-resistant cushions, insulation, tubing, valve components, and backlighting panels.

An important consideration is that aerospace plastics must meet specific flame, smoke, and toxicity requirements. Suitable materials include Nylon (some grades include Nylon 6), PEEK, Ultem, and PPS.