Aerospace CNC machining: Lightweight titanium parts and more

Aerospace CNC machining

The global aerospace industry is a hotbed of innovation in design and manufacturing, producing millions of complex metal parts every year.

An key tool used in this industry is CNC machining. Aerospace machining results in advanced aircraft parts made from light metals such as titanium and aluminum, and machining is also a valuable prototyping tool for aerospace R&D departments.

Aerospace machining also covers a range of applications—commercial aircraft, military vehicles, or even space travel, CNC machining plays a significant role in the development and production of precision aerospace components.

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 jetstream?

Aerospace is a highly diverse market comprising many sub-sectors, covering everything from industrial aviation to space exploration. Its value is estimated at around $800 billion as a global sector.

Aerospace production involves making parts for commercial, industrial and military customers, and the government is the largest contractor in the industry. In the U.S., for example, the two largest buyers of space commodities are the Department of Defense and NASA, the U.S. aerospace research agency.

Due to the vast number of sub-sectors and the multitude of applications and products within those sub-sectors, aerospace requires a broad range of manufacturing technologies, from traditional techniques just like casting and welding to cutting-edge systems like metal additive production. Aerospace CNC machining sits somewhere between those two extremes, being a highly established technology that nonetheless offers cutting-edge design and material possibilities.

What’s air hole machining?

Air hole machining is the manufacturing process of removing a portion of material from a workpiece using machine-operated cutting tools. CNC machining is the digital version of machining: computer-controlled electric trimming equipment to form new parts quickly and accurately.

Jetstream CNC engineering can be traced almost back to the invention of computer numerical control machining itself in 1942. One of the earliest applications of visibility CNC machining was the production of bulkheads and wing skins. Today, many aerospace parts can be machined, such as transmissions, landing gear components and electrical components. Projects can also be used to repair or modify existing parts, add detailed features, or add engraved textual information such as serial numbers.

Because many conscious machining jobs involve the creation of critical end-use components, a high-quality 5-axis engineering center is required for precision machining. Tolerances may be required for some parts, such as jet engine parts, since they are tight starting at 4 microns, much tighter than is usually acceptable during CNC machining.

Spatial machining can be an important form of prototyping during research and development. Computer numerically controlled machines are suitable for prototyping metal airspace components that will then be fabricated using casting or other techniques.

aerospace machine parts
It is typically responsible for many aerospace components, from vital titanium aircraft engine components to lightweight plastic interior cabin components.

Parts suitable for cat CNC machining are low-volume parts that require high strength and fine features. The size of such parts is usually limited by the size of the CNC machining center, but several different components are available – usually titanium or aluminum alloys, but additional options such as engineering plastics and composites also work. Some parts may only be post-machined after casting or extrusion.

Aerospace engineering can be used for prototypes and end-use parts. However, end-use components must meet stringent safety standards, standards and certifications.

Machinable female parts include (but are not limited to):

Landing gear parts
Turbine blades and various other jet engine components
Engine housings
Motion controls
Oxygen generation systems
Seating, armrests, and trays
Electrical connectors to get electric devices
Actuators
Filter bodies for liquid and air filtration systems
Wing ribs
Discs
Shafts pertaining to power transfer
Missile housings and other components
Cabin parts
Fuselage components

Aerospace CNC machining is definitely a critical program that can’t go wrong. Where some industries allow for loose tolerances and material variations, ceilings require complete precision and consistency for human safety.

Different applications and components have to meet different requirements and certifications, and there are some country-specific standards as well as international standards. However, a particularly important certification for many applications may be the AS9100 Qualification, an SAE International Standard awarded to suppliers and described in the aerospace sector as “for design, development, production, installation and service Models for Quality Assurance”.

As an extension of ISO 9001, not all aerospace parts production requires AS9100 certification, but customers can seek out suppliers who are qualified for quality assurance.

Other essential certification for tail wind machining consist of ITAR (International Traffic in Arms Regulations), a set of guidelines by the US State Department outlining US requirements for selling and producing technology on the US Munitions List, and AS9102 First Article Inspection Reports, which indicate compliance with the verification requirement jetstream parts.

While aerospace prototyping does not necessarily require such certification, as the prototypes will not be used on active aircraft.

Aerospace Processing Materials
CNC machining is generally a versatile process that can be used to make metal and plastic parts. In aerospace, however, two special metals dominate: titanium and aluminum. This is due to the high power of the material (especially titanium) and the light weight (especially lightweight aluminum).

Titanium
There’s no industry in the world uses more titanium alloys than aerospace. It’s easy to see why: this steel has an excellent strength-to-weight ratio, resists corrosion, and exhibits high standards at extreme temperatures. Titanium has become a major material in aerospace production and its use will increase further over the next century.

Aircraft that use large amounts of titanium in various components include commercial vehicles such as the Airbus A380 and Boeing B787, as well as military aircraft such as the F-22, F/A-18 and UH-60 Black Hawk helicopters.

Titanium space parts contain airframe and aircraft engine elements such as discs, cutting blades, shafts and casings. Many of them can be precision machined.

Because it’s harder than aluminum, it can be trickier for CNC machines, causing equipment wear and heat build-up. This means that aerospace engineering for titanium may require lower machine speeds and larger chip loads. (See our 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 alloy
Another metal widely used in aerospace engineering – and one that has been around longer than titanium and modern batards – can be aluminum.

Aluminum alloys are lightweight and have higher tensile strength. Aluminum forms an oxide coating when exposed to air, making it resistant to corrosion, and it is also very formable (more formable than titanium), which makes CNC machining easy.

Because it’s harder than aluminum, it can be trickier for CNC machines, causing equipment wear and heat build-up. This means that aerospace engineering for titanium may require lower machine speeds and larger chip loads. (See our 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 alloy
Another metal widely used in aerospace engineering – and one that has been around longer than titanium and modern batards – can be aluminum.

Aluminum alloys are lightweight and have higher tensile strength. Aluminum forms an oxide coating when exposed to air, making it resistant to corrosion, and it is also very formable (more formable than titanium), which makes CNC machining easy.

In CNC machining, the most common aluminum alloy is definitely the lightweight aluminum 7075, whose main alloying element is zinc. 7075. It is not as easy to be machined as other metals, but it has excellent fatigue strength. For example, many wings, fuselage and supporting structural elements are made of this material.

Other machinable aerospace aluminum alloys include 4047 (cladding/filler), 6951 (finned) and 6063 (structural). 6000 series alloys are generally considered easier to machine than other alloys.

Inconel superalloys
The Special Metals Corporation has developed a variety of austenitic nickel-chromium-based superalloys called Inconel.

One particular grade of the materials, Inconel 718, was developed specifically designed for aerospace applications. One of its first high-profile uses was for the jet engine diffuser case ( an extremely high-pressure part that joins the compressor to the combustor) of the Pratt & Whitney J58 engine, which was used in vehicles like the Lockheed SR-71 Blackbird.

Special Metals Corporation has developed a variety of austenitic nickel-chromium-based superalloys called Inconel.

A particular grade of material, called Inconel 718, was developed specifically for aerospace applications. Its first high-profile use was in the jet diffuser housing (the high-pressure part connecting the compressor and combustor) for the Pratt & Whitney J58 engine used in vehicles such as the Lockheed SR-71 Blackbird.

More recently, Elon Musk’s SpaceX used Inconel 718 in the engine manifold of its Merlin engine, which powers the Falcon 9 launch vehicle. It is also present in other aerospace components such as turbine blades, ductwork and engine exhaust systems.

As a work hardening metal, Inconel 718 must be machined in as few passes as possible; machinists typically use hard slicing tools for aggressive but slow cuts. However, superalloys offer good weldability.

Engineering plastics
In addition to metals such as titanium and aluminum, aerospace engineering also involves the use of high-performance plastics such as PEEK, polycarbonate and Ultem.

Plastics can be a useful replacement for metals due to their light weight, good shock and vibration resistance, sealing properties and chemical resistance. They also provide excellent electrical insulation to metals.

Visibility CNC machining of engineering plastics can produce air vent parts such as cabin interiors, tray tables, armrests, housings, wear pads, insulation, pipes, valve parts and backlit instrument panels.

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

TIKPRECISION is absolutely a CNC engineering specialist for customers in the aerospace industry. Contact us for a free quote.