Worth over $800 billion, the global aerospace industry is ripe with innovation. This industry is consistently at the cutting edge of new manufacturing practices and technologies.
Aerospace CNC machining is now one of the most critical components of the industry. The reason for this is not far-fetched.
One of the most important factors when producing parts for aircraft or related systems is, of course, safety.
Regardless of the aerospace project you are working on; every aircraft component must meet the highest industry standards.
There is no room for human error in the production and assembly of an aircraft. From the smallest interior detail to the plane’s exterior, any flaws or inconsistencies can have devastating effects.
The extremely high level of precision needed within the aerospace industry makes CNC machining a suitable manufacturing process for the sector.
The capability of this process to achieve very tight tolerances for metal and plastic parts allows it to offer robust solutions in the industry.
This article provides you with a complete guide to aerospace machining and its importance.
What Is Aerospace CNC Machining?
This CNC machining process involves creating CNC machining aerospace parts to assemble and maintain aircraft and space shuttles.
Aerospace CNC machining companies use kits, components, and assemblies which are essential for crafts used in the aerospace industry.
Aircraft parts, ranging from bushings, hinges, clamps, or other custom parts, need to come with high-quality materials.
This is to ensure that these aircraft components function properly without involving any form of danger.
This is why Titanium and Kovar are popular as the most used metals for aerospace components. Other materials may include aluminum, stainless steel, copper, bronze, and some types of plastic.
Materials Used In Aerospace CNC Machining
Aerospace machining is an adaptable process. However, not all metals and plastics are ideal for making aerospace parts. Below are the materials used in aerospace machined parts.
Aluminum and Aluminum Alloys
Aluminum is one of the most widely used metals for machining aerospace parts, primarily due to its high tensile strength and lightweight.
Besides, aluminum is very formable, which makes it simple machining for CNC machines.
The most popular aluminum alloy for CNC machining in the aerospace industry is aluminum 7075, whose primary alloying component is zinc.
It offers good fatigue strength. The material has been used to produce several wings, fuselage, and support structure components.
The aircraft aluminum alloys 4047 (cladding/filler), 6951 (fins), and 6063 (structural) are also machinable.
Therefore, alloys of the 6000-series are typically considered easier to machine than others.
Titanium and Titanium Alloys
Aerospace is the sector that employs titanium alloy the most globally. The metal works well at high temperatures, resists corrosion, and has a good strength-to-weight ratio.
The usage of titanium in aerospace manufacturing has become commonplace.
Commercial and military aircraft like the Airbus A380 and Boeing B787 and helicopters like the F-22, F/A-18, and UH-60 Black Hawk all need significant amounts of this material for their different parts.
Components for airframes and jet engines made of titanium include discs, blades, shafts, and casings.
It can be more difficult to CNC machine titanium since it is harder than aluminum, often leading to tool wear and heat buildup, which could distort the material.
As a result, titanium aerospace machining need to run at a lower machine RPM and with a higher chip load.
Engineering Plastics
Due to their incredibly low weight, excellent impact and vibration resistance, sealing capabilities, and chemical resistance, plastics might be a valuable alternative to metals.
Besides, compared to metals, they provide better electrical insulation and are ideal for prototype CNC machining.
PEEK, polycarbonate, and Ultem are high-performance polymers used in aerospace machining.
Aerospace engineering plastics can be CNC-machined to create aircraft parts like cabin interiors, tray tables, wear pads, armrests, back-lit instrument panels, valve components, housings, tubing, and insulation.
Not all engineering plastics are ideal for use in aerospace CNC machining, as aircraft polymers must adhere to particular standards for toxicity, smoke, and flame. So it is a crucial factor.
Machining Processes For Aerospace CNC Machining
The aerospace industry has a high demand for parts with extreme precision, so aerospace precision machining is needed.
The reason is that most parts have complex designs and geometries. There are various CNC machine types, but for high precision, the aerospace industry employs two major CNC machine operations.
Precision CNC Milling
This is a multi-axis machining process that involves the use of a milling machine to produce parts.
The machine used for this production moves along the convention X, Y, and Z linear axes and A and B rotational axes, consequently allowing the creation of intricate shapes and geometries.
While it is possible to use a 3 or 4-axis CNC milling machine when machining aerospace parts, it is better to use 5-axis CNC milling as they can work on up to 5 directions of the workpiece in a single operation.
This helps manufacturers reduce errors and lead time. Also, the cutting tools used in 5-axis CNC machines spin at high speeds, ensuring part accuracy and precision.
CNC milling facilitates the precision production of aerospace parts such as landing gear, electrical components, and transmissions.
Precision CNC Turning
This procedure, also known as subtractive machining, involves removing material to generate the desired shape.
The precision turning production process holds material bars in a wedge shape and rotates. This process continues until the material attains the desired shape.
CNC precision turning is a detailed and intricate process for creating aerospace parts with cylindrical shapes.
It is also important to note that this process is highly precise, as the computer controls the speed and position of the tool and material used.
CNC precision turning produces aerospace parts such as screws, nuts, threads, connector pins, fasteners, and shafts.
Typical Surface Finishes For CNC Aircraft Parts
Surface finishes for CNC machined aircraft components are very important for enhancing the durability, performance, and aesthetics of components.
Anodizing, plating, powder coating, and brushed and polished finishes are some of the most popular options available.
Each of these finishes has their own unique benefits and drawbacks, so it’s important to understand what is right for your specific application.
These finishes also protect parts from environmental factors and reducing wear and tear. Here is an overview of 8 standard surface finishes used in aerospace machining
#1. Anodizing.
Anodizing is a process that enhances corrosion resistance and wear resistance through the electrochemical conversion of the metal surface into a durable, corrosion-resistant anodic oxide finish.
This finish is particularly useful for aluminum parts, helping to withstand the harsh conditions of aerospace environments.
#2. Passivation.
Passivation involves treating or coating a metal in order to reduce the chemical reactivity of its surface.
In aerospace, stainless steel components often undergo passivation to remove surface contaminants and enhance corrosion resistance, ensuring longevity and reliability.
#3. Polishing.
Polishing provides a smooth and shiny surface by physically rubbing the material or using chemicals. This finish not only enhances the aesthetic appeal of aerospace parts but also reduces the adhesion of contaminants on the surface.
#4. Powder Coating.
Powder coating applies a free-flowing, dry powder that forms a skin-like finish when cured under heat.
It offers excellent durability and resistance to chipping, scratching, fading, and wearing, which is ideal for parts exposed to harsh operational conditions.
#5. Painting.
Painting is used to apply a specific color or protective coat to aerospace parts. It provides corrosion resistance, solar reflectivity, and can be used to apply company colors or visibility markings crucial for safety and branding.
#6. Hard Coating.
Hard coating refers to the application of a hard, durable film on the substrate of parts to improve wear resistance and life span. In aerospace, this could mean ceramic coatings that also provide thermal insulation.
#7. Thermal Spray Coating.
Thermal spray coating involves the projection of molten or semi-molten materials onto a surface to provide a coating.
This process is used to improve or restore the surface’s properties or dimensions, thus extending the life of aerospace components by providing protection against high temperatures, corrosion, and wear.
#8. Electroplating.
Electroplating is the addition of a metal coating on an object by putting a negative charge on it and dipping it into a solution containing a salt of the metal to be deposited.
This process is used in aerospace to enhance electrical conductivity, reflectivity, corrosion resistance, or to reduce friction on parts.
How Important Is Precision When CNC Machining Aerospace Parts?
Precision in CNC machining for aerospace parts is not just a requirement but a fundamental aspect that determines the safety, performance, and reliability of aerospace vehicles.
Whether manufacturing structural components for aircraft or intricate parts for spacecraft, the margin for error is minimal.
- Safety: Aerospace components are critical to the safety of the vehicle and its occupants. Even the smallest deviation from the design specifications can lead to catastrophic failures. Precision machining ensures that parts meet exact dimensions and tolerances, crucial for maintaining structural integrity and operational safety.
- Performance: Aerospace vehicles operate under extreme conditions, and every part must perform its function flawlessly. Precision in CNC machining ensures that components like turbine blades, fuselage panels, and navigation instruments operate efficiently, enhancing the overall performance of the aircraft or spacecraft.
- Compliance with Standards: Aerospace manufacturing is heavily regulated, and adherence to international and national standards is mandatory. Precision machining helps ensure that parts comply with stringent industry standards such as those set by the Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA).
Tips for Optimizing CNC Machining Processes
- Utilize Advanced CNC Machinery: Employing state-of-the-art CNC machines that offer enhanced capabilities such as 5-axis CNC machining can significantly improve the precision of aerospace components. These machines allow for complex shapes to be machined in fewer setups, reducing the risk of human error.
- Choose Appropriate Cutting Tools: The selection of cutting tools has a profound impact on the precision of the final product. Tools specifically designed for aerospace materials like titanium and high-strength alloys ensure better tolerances and surface finishes.
- Implement Tight Quality Control Measures: Rigorous quality checks at each stage of the machining process help detect deviations early and prevent the accumulation of tolerances. Use of advanced measuring and inspection systems, such as coordinate measuring machines (CMMs), ensures that each part meets the required specifications.
- Expert Programming for CNC Operations: Skilled CNC programmers play a crucial role in machining precision parts. Detailed and accurate programming ensures that the machine paths are optimized for the specific material and geometry, minimizing errors and material wastage.
- Regular Maintenance of Equipment: Consistent maintenance schedules for CNC machines and tools prevent potential malfunctions that could lead to inaccuracies in machined parts. Regular calibration and servicing ensure that machining processes remain accurate and efficient.
- Use of High-Quality Materials: The quality of the raw materials used in aerospace machining significantly affects the outcome. High-grade metals and composites reduce issues like tool wear and material deformation, which can affect the precision of CNC machining.
Challenges For Aerospace CNC Machining Services
Precision and Complexity:
Complex Part Geometries
Many aerospace parts are designed with intricate and complex shapes. Obviously, these are more challenging to machine accurately when compared to the simple custom machined parts.
Our CNC machines need to handle 3D contouring, multi-axis machining, and intricate designs, while also being optimized for small parts and micromachining projects.
Close-Tolerance Precision
Aerospace components generally require very tight tolerances to ensure proper fit and function.
Our CNC machines must be capable of producing parts with high precision, sometimes in the range of microns, to meet these requirements.
Whether we’re CNC grinding aerospace springs with 0.002” diameters or Swiss turning complex cylindrical components with 7-axis geometries, HyTech maintains extremely high levels of accuracy and repeatability.
Difficult-to-Machine Materials:
Exotic Metals and Composites
Modern aerospace components are often made from specialized metals like titanium, tungsten, and Inconel.
Advanced engineering plastics and composites are also increasingly used.
These materials are more challenging to machine due to their exceptional density, surface hardness, abrasiveness, and heat resistance.
Specialized tooling and unique machining processes are often required to achieve the same level of precision and repeatability that we do with standard steel and aluminum materials.
Higher Standards in Aerospace Quality and Consistency:
Safety and Quality Standards
The aerospace industry is highly regulated and extremely strict on quality control.
All CNC machining processes and materials must meet the required regulatory and documentation standards, such as AS9100:D, ISO 9001:2015, and NADCAP.
This requires comprehensive quality control and documentation throughout the manufacturing process.
Traceability
There is an increased need for traceability throughout the modern aerospace manufacturing sector.
Every custom machined part should be tracked from raw material to finished product to ensure quality and compliance with regulatory requirements.
Applications Of Aerospace CNC Machining
CNC machining is used to produce numerous aerospace parts and components. Just some of them include:
#1. Engine Components.
CNC machining is used extensively in the production of critical engine parts for aerospace, such as turbine and compressor blades, fan discs, fuel nozzles, engine casings and combustion chambers.
CNC machining allows for complex geometries, intricate cooling channels and high-temperature materials necessary for efficient and reliable engine performance.
#2. Structural Components.
CNC machining plays a crucial role in manufacturing structural parts like aircraft frames, wing spars, bulkheads, brackets and landing gear components.
These components demand exceptional precision and strength, high-quality surface finishes and proper alignment to withstand the extreme stresses of flight.
Composite structures are increasingly being used in aircraft structures to reduce weight and improve fuel efficiency.
CNC machines equipped with specialized cutting tools and processes can shape, trim and finish components made from composites like carbon fiber and glass-reinforced epoxy.
#3. Avionics And Electrical Components.
CNC machining is commonly used to manufacture various electronics components used in aircraft systems such as control panels, connectors, sensor housing and instrument cluster components.
These parts demand precise machining to ensure proper functionality, electrical connectivity and component integration.
The technology is also used to produce enclosures for avionics systems – the electronic, instrumentation and navigation systems used in aircraft.
These systems are crucial for accurate data collection, control and communication in aircraft systems.
Avionics enclosures require precise cutouts, holes and mounts to accommodate various components and ensure electromagnetic shielding.
#4. Interior And Exterior Trim.
CNC machining is employed to manufacture interior and exterior trim parts, including cabin panels, seating structures, winglets, fairings, airframe assemblies, emblems and decorative accents.
CNC machining enables the creation of intricate designs, precise cutouts, and fine details that enhance the aesthetics and functionality of a vehicle’s interior and exterior, while also being lightweight.
#5. Prototyping.
Prototyping allows engineers and designers to create functional models of aerospace parts and assemblies, enabling them to evaluate the design, fit and functionality before proceeding to full-scale production.
CNC machining enables the rapid production of intricate and precise prototypes that closely resemble the final components.
#6. Maintenance, Repair And Overhaul (Mro).
CNC machining is used extensively in the MRO sector of the aerospace industry.
It is employed for the repair and refurbishment of numerous components, such as engine parts, landing gear components, and structural elements.
CNC machines allow for accurate re-machining and re-conditioning of worn or damaged parts, ensuring their continued safe and reliable operation.
Benefits Of Using Aerospace CNC Machining
CNC machining significantly improves the manufacturing process and enhances the performance of aerospace parts.
This section explores the diverse advantages of CNC machining, particularly focusing on its contribution to creating components that are lightweight, error-free, and highly consistent.
#1. Lightweight Components.
One of the most significant benefits of CNC machining in aerospace is its ability to fabricate lightweight components.
Aerospace engineers continually seek methods to reduce the weight of parts to enhance fuel efficiency and performance of aircraft.
CNC machining allows for the production of complex geometries that are not only robust but also significantly lighter than those made with traditional manufacturing methods.
Utilizing materials like aluminum and titanium, which are renowned for their strength-to-weight ratio, CNC techniques ensure that the aerospace components are optimal for use without compromising on durability.
#2. Minimize Part Errors.
The precision inherent in CNC machining processes is critical for minimizing errors during the production of aerospace parts.
Advanced CNC machines offer high repeatability with tight tolerances that are crucial in the aerospace sector where every micron counts.
This precision reduces the risk of part failure, thereby enhancing the safety and reliability of aerospace components.
By automating the machining process, CNC technology also minimizes human errors, ensuring each part is produced with exact specifications.
#3. Accuracy and Precision.
CNC machining provides unmatched accuracy and precision, which are indispensable in the aerospace industry.
The ability to adhere to strict manufacturing standards and achieve tolerances as tight as a few microns makes CNC machining ideal for aerospace applications.
This level of precision is essential for parts that must withstand extreme conditions and stresses, ensuring they function reliably in critical applications, such as in engines and structural components of spacecraft and aircraft.
#4. Consistency.
Another advantage of CNC machining is the consistency it brings to part production.
Whether it’s a single part or thousands, CNC machines produce each component with the same precision and specifications, reducing variability that can affect the performance of aerospace components.
This consistency is crucial for maintaining the quality and reliability of parts across different batches, thereby supporting the aerospace industry’s need for uniformity in high-volume production environments.
#5. Efficiency.
CNC machining stands out in the aerospace sector for its efficiency.
The integration of CNC machines facilitates the automation of production processes, allowing for continuous operation without the inconsistencies associated with manual labor.
This not only speeds up the manufacturing cycle but also maximizes the utilization of materials and resources.
The precision of CNC machinery ensures that each component is produced with minimal waste, optimizing the use of valuable materials like titanium and aluminum alloys.
This efficiency is crucial in an industry where time and resource management directly impact financial and operational success.
#6. Reduces Manufacturing Costs.
Implementing CNC machining in aerospace manufacturing significantly reduces costs.
By automating many of the processes traditionally done by hand, CNC machines decrease the need for extensive labor, which is a major expense in any industry.
Additionally, the high precision of CNC machining minimizes material waste and reduces the incidence of errors that can lead to costly rework or scrap.
The ability to produce components quickly and accurately also shortens the time to market, further reducing overhead costs and enhancing the profitability of aerospace manufacturing operations.
#7. Achieve Complex Geometries.
The capability of CNC machining to achieve complex geometries is particularly beneficial in the aerospace industry.
Aerospace components often require intricate designs with precise dimensions and tolerances, which are difficult to achieve with traditional manufacturing methods.
CNC machines, especially those operating with 5-axis capabilities, can create detailed, complex shapes that meet the stringent requirements of aerospace parts.
This ability allows for the design and production of more advanced and efficient aerospace systems, contributing to the overall improvement in aircraft performance and functionality.
#8. Speed.
Speed is another critical advantage offered by CNC machining. Compared to traditional manufacturing methods, CNC machining produces parts at a significantly faster rate, which is vital in an industry where meeting project deadlines can determine the success of aerospace programs.
The rapid production capabilities of CNC machines also enable faster prototyping, allowing aerospace engineers to test and refine their designs more quickly.
This accelerates the development cycle and brings innovations to market faster, providing a competitive edge in the rapidly evolving aerospace sector.
Limitations Of CNC Machining In The Aerospace Sector
While CNC machining is a highly versatile and widely used manufacturing process in the aerospace sector, it does have certain limitations.
Although many of these can be overcome through process optimization, tooling advancements and a thorough understanding of the design requirements.
Complexity Of Shapes
CNC machining is well-suited for producing parts with relatively simple to moderately complex geometries.
However, when it comes to extremely intricate or highly contoured shapes, CNC machining may have limitations.
For example, there may be constraints related to undercuts, deep cavities or internal features that are difficult to access with standard cutting tools.
Complex or highly intricate parts may require specialized tooling or additional operations, adding time and cost to the manufacturing process.
Material Restrictions
CNC machining can work with many materials commonly used in aerospace, such as aluminum, titanium and composites.
However, certain materials may pose a challenge. For example, some advanced high-temperature alloys or superalloys used in aerospace engine components can be difficult to machine due to their hardness or heat resistance.
Specialized tooling and techniques may be required to effectively machine such materials.
Size Limitations
Industrial CNC machines come in various sizes. The size of the machine defines the maximum size of parts it can accommodate.
Large-scale components, such as aircraft wings or fuselage sections, may exceed the capacity of standard CNC machines.
Alternative manufacturing methods could be a better option to fabricate these oversized components.
Cost Considerations
CNC machining can be a cost and time-effective method for making aerospace components, especially for medium to high-volume production runs.
However, for low-volume or one-off parts, the setup and programming costs associated with CNC machining may make it less viable compared to additive manufacturing (3D printing), for example.
Additionally, CNC machining can be a time-consuming process, especially for complex parts, due to the need for multiple machining operations and setup times.
Surface Finishes
While CNC machining can achieve high precision and accuracy, the surface finish of machined parts may require additional post-processing.
Aerospace components often have strict surface finish specifications, such as low roughness, absence of burrs or specific coatings.
Achieving these requirements may involve secondary processes, such as grinding, polishing or coating, which add time, cost, and complexity to the manufacturing process.
Operator Skill And Training
CNC machining requires skilled operators to program, operate and maintain the machines effectively.
The complexity of CNC programming and operation requires proper training and expertise.
Finding and retaining skilled CNC operators can be a challenge, particularly where there is a shortage of qualified personnel.
The Future Of Aerospace Cnc Machining
Technology is continuing to evolve and innovate at an incredibly rapid pace. Aerospace manufacturers have to stay on top of these trends to compete. Several vital trends will likely drive the future of CNC machining in the aerospace industry:
- Additive manufacturing: Integrating additive manufacturing (3D printing) with traditional CNC machining will enable the production of complex parts with unique geometries that were previously impossible or too costly to manufacture.
- Smart manufacturing: The adoption of Industry 4.0 technologies, such as IoT devices, will allow for real-time monitoring, data collection, and analysis in CNC machining processes. This will enable manufacturers to optimize operations, improve quality control, and reduce waste.
- Digital Twins: Creating a digital replica of a physical CNC machine to analyze and optimize its performance is another technology gaining traction. This process can facilitate more efficient machine setups, preventive maintenance, and remote troubleshooting.”