3D Printing in Aerospace: Materials, Processes, and Classifications
3D printing, also known as additive manufacturing, is highly valued in the aerospace industry. In an industry where weight or drag reduction can lead to huge cost savings, 3D printing has enabled aerospace manufacturers to create lighter and more fuel-efficient aircraft in a more cost-effective manner. The aerospace industry was one of the first industries to widely adopt 3D printing in the manufacture of key components, and the process has redefined the boundaries of design and manufacturing. Aerospace engineers were instrumental in the development of the 3D printing process, and the industry continues to reap the benefits today as 3D printing matures as a manufacturing process.
From jigs and prototype tooling to end-use parts like nozzles and control consoles, 3D printing in aerospace can be used to both aid the manufacturing process and satisfy particular applications within an aircraft. This article will discuss 3D printing in aerospace, the materials and processes used, and its different applications.
What Is 3D Printing?
3D printing, also known as additive manufacturing, is a manufacturing process that creates parts layer by layer until the entire three-dimensional part is complete. It is the opposite of subtractive manufacturing processes like CNC (computer numerical control) machining where the material is removed from a workpiece to create parts. 3D printing can be used to manufacture trinkets, simple tools, and advanced components used in several industries such as aerospace, automotive, medical, machinery, and more. While 3D printing technology has existed since the 1980s, its use has exploded since the start of the 21st century as additive manufacturing has become a sound alternative to produce parts that require several processes to manufacture.
When Did the Aerospace Industry Start Using 3D Printing?
The aerospace industry was one of the first industries to implement 3D printing in 1989. Since the inception of 3D printing technology in the 1980s, the aerospace industry has been one of the largest contributors to the development of 3D printing processes and technology. Today, the industry remains one of the largest beneficiaries of the process and accounts for nearly 16% of the total revenue generated by the additive manufacturing industry.
How Did 3D Printing Start in the Aerospace Industry?
The origin of 3D printing in the aerospace industry dates back to the late 1980s. At the time, the largest benefactors of 3D printing were the US military and the defense industry. These two organizations widely used plastics as a cheaper alternative to metals to conduct testing and simulation of various aircraft systems and components.
3D printing was mainly used for prototyping and testing in the aerospace industry until the mid-2000s when it became possible to 3D print flame-retardant plastics through processes like selective laser sintering. As advancements in 3D printing continued throughout the first two decades of the 21st century, its use in aerospace applications expanded. Now it is used for applications throughout the aerospace component lifecycle, including: prototyping and validating designs, tools, jigs for aircraft maintenance, end-use parts in jet engines, and aircraft interiors.
What Kinds of Materials Are Used in 3D Printing for Aerospace Applications?
A number of different materials are used in aerospace industry applications. Common materials used are listed and described below:
Ceramics are inorganic, non-metallic materials. They are great for aerospace applications due to their corrosion resistance, light weight, and wear resistance. However, ceramics are exceptionally hard and brittle, making them difficult to fabricate into parts. Kaolin and porcelain clay are two examples of ceramics that can be 3D printed to make parts. Ceramic 3D printing can be used to make satellite mirrors which are made from silicon carbide, with the goal of reducing weight and improving stiffness to strength ratio.
2. Carbon Fiber
Carbon fibers are long, exceptionally thin but strong strands of carbon atoms. Carbon fiber composites are ideal for aerospace applications since it is as strong as steel but lighter than aluminum. This allows manufacturers to improve aircraft performance by integrating 3D-printed carbon fiber parts into aircraft frames and structures. However, carbon fiber is expensive and difficult to produce, which limits the potential applications it can have in the aerospace industry.
Glass is an amorphous material that is made by the rapid quenching of a molten mixture of silica and other ingredients. Glass is a transparent and brittle material that has been used since ancient times. While it may often be associated with windows, 3D-printed glass is not used for windows in aircraft. Instead, glass-filled filaments and powders are often used to reinforce plastics and to make glass composites which are helpful in reducing aircraft weight.
Metals are naturally occurring ductile and lustrous materials that are excellent conductors of heat and electricity compared to other materials. Metals like aluminum and titanium are widely used in aircraft due to their corrosion resistance and high strength-to-weight ratios. 3D-printed metals are used in engine components, frames, structures, and electronics equipment. A major downside of metals is that they are heavy. Too much metal in an aircraft can adversely affect aircraft performance and fuel efficiency. Figure 1 is an example of a 3D printed turbine propeller:
3D printed turbine propeller.
Image Credit: Shutterstock.com/Matveev Aleksandr
Polymers are materials composed of repeating chains of molecules. Common examples of polymers in aerospace include synthetic thermoplastics like nylon and ABS (acrylonitrile butadiene styrene). These materials can be used to 3D-print interior components like seatback and wall panels or air ducts. Generally, polymers are great for aerospace applications since they are lightweight and durable. However, polymers are weak compared to metals and cannot be used for high load-bearing applications where metal is often preferred. For more information, see our guide on What Are Polymers.
Inconel® is a nickel-chromium-based superalloy valued for its strength at high temperatures and excellent creep and corrosion resistance. In 3D-printing aerospace applications, Inconel® is often used in jet turbine engines to make fuel nozzles. Inconel’s primary disadvantage is that it is an expensive material. For more information, see our guide on What is Inconel Metal.
Composite materials are composed of two or more constituent materials whose properties complement each other. Composite materials have structural benefits such as high strength and low weight, as well as increased wear resistance. Composite materials for 3D printing in aircraft lead to lighter and more structurally resilient aircraft since the desirable properties of different materials synergize. A downside of 3D-printed composite materials is that they are not biocompatible and can be expensive.
What Are the Steps in the 3D Printing Process in the Aerospace Industry?
3D printing can help validate part design and function and can be used for small-to-medium production volumes. The parts of the 3D printing process as it is used in the aerospace industry are listed and described below:
Aerospace designs commonly begin as concept models that showcase a particular aircraft component. Models are created in CAD software and then exported to a 3D-printer-friendly file format like .stl.
Before a design can be fabricated by a 3D printer, certain preparation work must be completed to ensure desired print quality. The preparation methods will differ depending on part geometry, the type of 3D printing, and the printer being used. Part models must be configured and oriented in printers in a manner that ensures optimal quality. Additionally, some printers, like FDM (fused deposition modeling) and SLS (selective laser sintering) printers, require build trays to be heated before printing.
After 3D models are configured as desired and 3D printing systems are properly prepared according to the type of 3D printing and printing machine used, parts can be fabricated. Print times vary from a few minutes to several hours depending on the size of the part and the type of printing used.
When 3D printing is completed, parts can be removed from the build tray. All 3D printed parts require some post-processing. However, parts printed by one method may require more post-processing than those produced by another method. For example, FDM printed parts often only require support material to be removed while DED (direct energy deposition) printed parts require additional machining processes to obtain desired dimensions.
Once post-processing is completed, the 3D printed part is tested and evaluated. If design modifications are needed, 3D printing enables designers to quickly create and test new designs. When a 3D-printed part’s intended function is satisfied, the part can be 3D printed for small-to-medium batch production or manufactured by more traditional methods.
What Are the Different Types of 3D Printing Used in the Aerospace Industry?
There are several different types of 3D printing that can be used in the aerospace industry. These are listed below:
1. Fused Deposition Modeling (FDM)
Fused deposition modeling (FDM) is a type of 3D printing that utilizes an extruded thermoplastic filament to make parts layer by layer. Molten plastic is extruded out of a nozzle onto a build tray. When the first layer cools, the following layer is deposited. This process repeats, layer by layer until the entire part is complete. FDM printing in aerospace is intended more for prototyping and design verification purposes than functional aircraft parts.
2. Stereolithography (SLA)
Stereolithography (SLA) is a 3D printing process that utilizes precisely placed photosensitive polymer resin that is cured by UV light to make parts layer by layer. SLA offers the highest resolution of any form of 3D printing and is often used to make cabin accessories like door knobs and seat back panels.
3. Selective Laser Sintering (SLS)
Selective laser sintering (SLS) is a 3D printing process that precisely sinters and fuses thermoplastic powders to form parts layer by layer. When a layer is completed, more powder is deposited, the build tray descends, and the process repeats. SLS is great for producing parts with complex geometries at high resolutions. SLS 3D printing in aerospace is commonly used for small-batch production of flexible airflow components like air ducts and heat-resistant parts like nozzle bezels.
4. Electron Beam Melting (EBM)
Electron beam melting (EBM) is a 3D printing process that uses electrically conductive metal powder and electron beams to manufacture parts layer by layer. The printing process must occur in a vacuum to prevent gas molecules from interfering with the energy emitted by the electron beam. The electron beam heats the metal powder to extremely high temperatures (1112-1292 °F) to melt and fuse it together to form parts. EBM can be used to make metal components like suspension wishbones.
5. Direct Energy Deposition (DED)
Directed Energy Deposition (DED) is a 3D printing process that uses an energy source such as an electron beam, laser, or plasma arc to melt powder or filament as it is deposited from a nozzle. The process is similar to EBM but does not require a vacuum to be completed. DED printing is commonly used to make metal parts in jet turbine engines.
What Are the Different Types of 3D Printing Machines Used in the Aerospace Industry?
The different types of 3D printing machines used in the aerospace industry are described below:
1. Powder Bed Fusion (PBF) Machines
Powder bed fusion (PBF) machines are 3D printing machines that deposit powders and fuse them together through processes like SLS or EBM. The advantages of PBF machines include the ability to recycle unused powder for future printing processes, a wide selection of plastic and metal materials to choose from, and minimal support needed to produce parts. The disadvantages of PBF machines include the high power requirements to print parts, parts susceptible to thermal distortion, and slow printing time.
2. Fused Deposition Modeling (FDM) Machines
FDM machines are 3D printing machines that create parts by extruding plastic filaments layer by layer. FDM machines have several advantages including low cost, small footprint, and a wide variety of materials available for printing. However, FDM machines also have disadvantages. Parts printed by FDM are prone to warping and are weak in directions perpendicular to the print layers. Additionally, FDM machines are prone to nozzle clogging and frequently require bed calibration.
3. Stereolithography (SLA) Machines
SLA machines are 3D printing machines that manufacture parts by curing photosensitive polymers with a UV lamp. The advantages of SLA machines include the ability to print highly accurate and precise parts, the ability to save unused resin for future print jobs, and the ability to print complex and intricate patterns. However, the disadvantages of SLA machines include high upfront and maintenance costs and resins are not environmentally friendly.
4. Direct Energy Deposition (DED) Machines
Direct energy deposition (DED) machines are 3D printers that produce parts by using a focused heat source such as a laser, plasma arc, or electron beam that melts the powder or filament. The primary advantages of a DED printer are that it allows the grain structure of printed parts to be controlled and enables large parts to be made with little tooling. Disadvantages of DED machines include parts made with poor precision and the need for post-processing to obtain desired dimensions. Additionally, DED machines are expensive and can cost over $500,000 which can be a barrier for many organizations.
5. Binder Jetting (BJ) Machines
Binder jetting (BJ) machines are similar to PBF (powder bed fusion) machines, but deposit liquid binding agents onto metal or plastic powders to fuse them together rather than using a concentrated heat source to fuse the powders. The advantages of BJ machines include the ability to produce parts with few or no internal supports, the ability to produce parts with low surface roughness, and the ability to produce large parts. The disadvantages of BJ machines include difficulty in controlling accuracy and tolerances due to shrinkage and weak parts due to porous structures. While sintering as a post-process can make parts stronger, the additional process adds more cost.
What Types of Applications Are 3D-Printed Parts Used for in the Aircraft Industry?
Listed below are some examples of parts that can be manufactured by 3D printing for the aircraft industry:
1. Engine Components
The materials used for engine components must withstand high mechanical and thermal stresses. Parts like fuel nozzles can be made by 3D printing processes like EBM (electron beam melting) and DED (direct energy deposition). Not only is the production of nozzles using these processes more efficient, but the nozzles themselves are lighter than those made by traditional manufacturing methods. This offers significant positive benefits related to aircraft performance and environmental impact.
2. Structural Components
Structural components are interior and exterior components that help form and support the rigid body of an aircraft. Structural components like brackets and wishbones can be made by 3D printing processes like EBM and DED using titanium and titanium alloys, copper, and nickel alloys.
3. Maintenance and Repair
Maintenance and repair are routinely conducted on aircraft to ensure their safe use and long life. 3D printing methods like EBM and DED can be used to fabricate jigs, fixtures, and tools needed to conduct maintenance and repair on aircraft out of titanium, stainless steel, and copper, among other metals.
4. Interior Components
Interior components in aircraft include everything from avionics equipment to cabin accessories like door latches and light fixtures. SLA (stereolithography) and SLS (selective laser sintering) are two popular methods of 3D printing commonly used to fabricate interior components for aircraft.
5. Prototyping and Tooling
Prototyping and tooling refer to the processes related to designing and testing new design concepts and developing the related tooling. 3D printing is great for creating prototypes and tooling for the aerospace industry due to its ability to make complex parts on demand with little setup work required. This allows for rapid development and testing of new products like suspension wishbones and nozzle bezels.
What Are 3D Printed Aerospace Parts?
The following are mechanical aerospace parts that can all be made by 3D printing:
- Fuel nozzles
- Door latches
- Lighting fixtures
- Trim pieces
What Are the Advantages of 3D Printing Technology in the Aircraft Industry?
There are several advantages of 3D printing applications in the aircraft industry. They are described below:
- Reduced Weight: 3D printing can be used to replace metal parts with lighter plastic parts. Components produced by 3D printing will reduce the aircraft’s overall weight, which consequently reduces fuel consumption and improves the aircraft’s performance.
- Cost-Effectiveness: 3D-printed parts can be made in far fewer process steps than parts produced by traditional manufacturing processes. Additionally, the process is entirely automated. This helps reduce overall production costs and waste.
What Are the Disadvantages of 3D Printing Technology in the Aircraft Industry?
There are also several disadvantages of 3D printing in the aircraft industry. Some disadvantages are described below:
- Limited Materials Available: While many widely used plastics and metals are compatible with 3D printing, thousands of alloys and compounds are still incompatible. This fact limits the potential applications for which 3D printing can be used in the aerospace industry.
- Weak Part Structure: Some 3D printing methods, like FDM (fused deposition modeling) and SLS (selective laser sintering), produce parts with anisotropic properties (characteristics that differ depending on the direction of an applied load). This can be undesirable for certain load-bearing parts and limits the potential of various 3D printing applications for the aerospace industry.
Who Uses 3D Printing in the Aircraft Industry?
3D printing is used by R&D firms, aircraft manufacturers, and maintenance companies. 3D printing can be used for rapid prototyping of aerospace parts, and small-to-medium batch production of end-use aerospace components, jigs, fixtures, and tools for aircraft maintenance. For more information, see our guide on the Uses of 3D Printing in the Aircraft Industry.
What Applications for 3D Printing Technology in the Aviation Sector Might There Be in the Future?
3D printing is a process that continues to positively impact the aerospace industry. It is poised to reduce the negative environmental impact of the aerospace industry, bolster innovation within the industry, and improve both aircraft performance and manufacturing efficiency for years to come. 3D-printed wings and green aviation are just two examples of future 3D printing applications in aerospace.
This article presented 3D printing in aerospace, explained what it is, and discussed its various processes and classifications. To learn more about 3D printing in various industries, contact a Xometry representative.
Xometry provides a wide range of manufacturing capabilities, including 3D printing and other value-added services for all of your prototyping and production needs. Visit our website to learn more or to request a free, no-obligation quote.
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