CNC machining for the aerospace industry

CNC machining in the contemporary aerospace industry is a standard. Although the first planes were built out of wood and canvas, the requirements of the industry grew, especially in the rigidity department. Broad usage of the lightest possible alloys and polymers enabled that industry to create lighter machines with traditional machining tools like mills or lathes.

The revolution brought by the jet engine technology pushed that industry even further – not only with achievable speed but also with the requirements for the precision of its part manufacturing. Such engines are the sole cause of development of the CNC machining that can deliver high repeatability of parts and precision of machining processes with tight tolerances. Since that moment (the first numerically controlled device was created in the 1950s) CNC machining has been inseparably connected to the aviation industry.

CNC machining for aerospace industry: specification and requirements

The contemporary aerospace sector – military and civil – requires parts that are rigid and provide longevity, even in the most demanding environments. High fluctuation of load, long exposure for very low or very high temperatures, or requirement to achieve the highest possible repeatability of manufacturing – these are only a few requirements for the parts made for the aviation industry. On top of that – each part should be as light as possible out of structurally coherent parts.

That is why the right selection of materials, suppliers, or thorough inspection of each piece of material before machining is crucial. The mentioned requirements make the professional CNC machining services for the aviation industry very demanding. In addition – such needs demand more than 'only' the best possible CNC machining devices, but also expertise and knowledge of the whole shop or plant team.

High-quality airplane parts can be manufactured – true to the requirements – only in machine shops that can provide very high precision CNC machining with perfectly calibrated devices (mills, lathes, grinders, or EDM devices), and knowledge of the CNC operators.

Perfect selection of materials and strict quality control – at every stage of the manufacturing process – translates into the production of the highest quality aviation parts. Such products – often with complex geometries and made precisely to the specification – can provide long and failure-free work for hundreds and thousands of hours.

It is worth mentioning that the utilization of the very high precision CNC machining can make that process more cost effective. Not only due to typical advantages (increase in the batch volume can lead to decrease in unit cost), but also thanks to the longevity provided by such a process.

The main reasons for such high requirements for aviation parts and their manufacturers are easiest to present in the example of the contemporary jet engine rotor blades:

• such parts work in extreme conditions – on one side is very cold air (commercial airline planes are cruising at an altitude between 33,000 and 42,000 feet / 10 to almost 13 kilometers above sea level); on the other – very hot environment (due to combustion inside the engine),
• are subjected to the continuous and high forces (omnidirectional),
• should be perfectly balanced to maintain optimal efficiency and avoid damaging other elements. Even the smallest variation in mass or crystal structure of an alloy can cause catastrophic failure,
• the selection of the materials for the aerospace CNC machining – even clearly described in specification – should be re-evaluated and the material for the manufacturing processes – go through in-depth quality control to ensure the best possible crystal structure of the particular batch. Such redundancy of quality control can deliver the best possible material for the manufacturing processes.

That is why precision, combined with the experience and knowledge of the CNC operators, is a must in the parts manufacturing processes for the aviation industry. On the one hand – the parts themselves are expensive, but the amount of work and responsibility corresponds with these demands.

CNC machining: inseparably connected to the aerospace industry

Currently, CNC machining is a standard in almost any industry that is focused on manufacturing high quantities of elements. Although that technology was founded and developed as a result of an order from the US Air Force, almost since its beginning spread out to other industries. Not only aerospace companies.

Scientists from the Massachusetts Institute of Technology created the first CNC device to manufacture parts for – at this time: cutting-edge – jet engines. In the 1950s such technology was in its infancy and the first challenges related to the new propulsion system for airplanes were strongly related to the precision of manufacturing. Technology – created and developed – by MIT scientists allowed to deliver repeatable parts in almost no time.

That allowed faster development of jet engines and the whole industry – at that time: mainly military, but the technology sinked into civilian avionics and helped to increase the efficiency of manufacturing processes (while maintaining cost efficiency). In other words: without CNC machining, the contemporary aviation industry would not look the same. To some extent – even the whole world.

Type of numerically controlled machining used in manufacturing parts for the aerospace industry

Parts manufacturing for the aviation industry – propellers, light planes, landing gears components and jets – are currently executed mainly with CNC devices. Even parts made out of polymers or composites are cut to the size and shape with numerically controlled machining. Mainly to minimize the possibility of error and provide the best possible precision of work.

Among the most often used CNC machining technologies for the aerospace industry, it is worth mentioning:

• CNC machining for aerospace parts – is one of the most important, if not – the most – types of machining for such an industry (and many more). Contemporary devices (that provide 2- and 3-axis machining, and even 5-axis CNC machining for more complicated processes) allow fast shaping of almost any type of aerospace component. From machining turbine blades and engine blocks with multiple cylinders, to seat farmers and cockpit equipment. In these applications, CNC mills have been used for decades,
• CNC turning – used to manufacture cylindrical objects. Often used in the manufacturing of drive shafts or bolts to connect bigger systems, often subjected to high stress,
• CNC grinding and sanding – used to provide glass-like surface finish of parts. Often used as a part of the preparation for the further processing of parts, eg. galvanic bettering to provide additional features for the surface. For example, aluminum anodization can improve parts' rigidity and longevity protecting their structure with a thin (but hard) layer of artificially created oxide (such layer has strong corrosion resistance),
• EDM (electrical discharge machining) – is used often in the manufacturing of aircraft components with complex internal structures. That process allows to creation of monolithic parts that are impossible to manufacture within multi-axis mills,
• laser cutting and laser marking – that allows to put temporary markings on the surface of parts. It is very important from the perspective of assembly and maintenance teams that should be able to identify elements even worn out. On top of that – laser cutting allows precision cutting of big parts of plane fuselage, even made out of polymers.

Materials used in aerospace machining parts

Aerospace industry since its beginning used the lightest materials possible. Such selection allowed taking off, and – in time – faster and higher cruises. Balsa and canvas – used at the beginning – are replaced by aluminum, titanium glass fibers, and a vast variety of polymers and composite materials. Each of these provides low mass and very good mechanical properties.

The contemporary CNC aerospace parts are made out of the following materials:

• aluminum alloys – especially series 6xxx and 7xxx (often called 'aviation grade aluminum') and specialized alloys from series 8xxx. That material has a very good strength-to-weight ratio, which is why it became one of the standards in the aerospace and defense industry. On top of that, parts made out of these alloys can be bettered in galvanic processes. Aluminum alloys are very machinable, which makes them a perfect material for many industries – aviation among many. Such alloy can be used in plane frames (eg. the F-16 airframe is made 80% out of aluminum), and even small elements in the cockpit of luggage compartments,
• titanium alloys – more and more popular material. Although at its beginning was used only in the most advanced (and expensive) machines, like SR-71 (that plane was a perfect example of titanium usage), now is often selected as the right alloy for modern civilian and military aircraft (eg. over 40% of F-22 Raptor is made out of titanium alloys). These alloys provide very good mechanical parameters and low mass. Due to high cost, titanium airplane parts are the most often made for the military,
• superalloys – often called heat-resistant superalloys – are used in jet engine manufacturing, eg. for the gas turbine blades. Made out of alloys of iron, nickel, and cobalt are heavier than aluminum, but have better resistance to the heat inside the engine,
• composites – a wide range of materials that include (in some classifications) even high-performance polymers. Due to low mass and high good enough mechanical properties are used to manufacture airplane fuselage or plane equipment.

One order, many benefits - this is how you work with RADMOT

At RADMOT, we offer CNC milling services, CNC turning services, as well as many additional services, including washing, aluminum anodizing, laser marking and assembly. We have at your disposal over 80 modern machines in our machine park, all from renowned manufacturers. Download the presentation and check on which machine tools we produce CNC turned parts and CNC milled parts.

Contact us and tell us what you need. We have been providing CNC services for almost 40 years. Our valuation is completely free. And if you're in doubt about which technology will work best for you, our expertise is at your service.