Several one-component and two-component epoxy adhesives are used by aerospace manufacturers for bonding, sealing, coating, potting, and encapsulating. Adhesives have been used for bonding the wings, fuselage, and several other basic aircraft components for over five decades. With the improvements in aerospace as well as adhesive technology, the popularity of structural adhesives among aerospace engineers has skyrocketed.
In this blog, we will learn about the role of structural adhesives in the aerospace industry, their benefits, and the factors that you need to consider before selecting an aerospace adhesive. It is crucial for aerospace engineers to know these things to make an informed decision.
A] Adhesive Applications In Aerospace
Aerospace adhesives are specially formulated adhesives designed to provide safe and reliable bonds at high altitudes. These adhesives are used for bonding, sealing, coating, potting, and encapsulating various parts of an aircraft or a satellite.
Traditionally screws, bolts, and rivets are used for fastening two or more substrates. However, aerospace structural adhesives offer similar or stronger bonds, uniform stress distribution, protection from vibrations and impacts, weather resistance, and temperature resistance. They are also significantly lighter, which is a huge benefit for the aviation and aerospace industries.
Adhesives can also reach minute spaces and cracks and hold them together. In addition to strong and durable bonds, aerospace epoxy adhesives are highly customisable. They can be formulated to have vibration resistance, thermal and electrical resistance, conductivity, and chemical and acid resistance. Such mechanical and chemical properties are not offered by any traditional bonding techniques.
B] Benefits Of Using Epoxy For Structural Bonding
1. Environmental Advantages
Epoxy resin was first used for aerospace bonding in the 70s. Back then they were only used for niche applications. However, with time, engineers understood the potential of aircraft structural adhesives. Traditionally used screws, bolts, and rivets are mostly made from metals, which are easily rusted when in contact with rain and winds.
Adhesives for the aerospace industry do not corrode or deteriorate when they come in contact with rain, wind or any other environmental factors. This improves the structural reliability of the craft in the long term. As a result, epoxy adhesives are used in several applications of aerospace bonding.
2. Longer Lifespan Of Components
Aerospace adhesives provide strong, durable bonds and improve stress distribution. They hold the components together for a longer period of time. In addition to strong bonds, they also ensure good aerodynamics, which further increases the lifespan of the components.
Adhesives can also be used for coating crucial metallic components to protect them from corrosion and other elemental factors. Heat-conducting adhesives can be used to create heat sinks, driving access heat away from important electrical components. Aerospace adhesives can also be used for potting micro-cracks, keeping the components in good condition for longer.
3. Reduced Weight And Sustainability Advantages
As we have mentioned above, adhesives are significantly lighter than metal fasteners. Using adhesives to bond different components, instead of hundreds of metal fasteners, which drastically reduces the weight of the final structure. Lighter aircraft require less fuel.
As the aerospace industry is one of the top contributors to the global population, airlines are trying to figure out ways to improve their carbon footprint. Several governments have already placed plans to incentivise airlines to reduce their carbon footprint. As a result, the demand for lighter aircrafts is likely to increase in the near future.
4. Bond Strength
Aerospace bonding solutions are capable of offering extremely high bond strengths, comparable to welding. However, unlike welding, adhesives can bond substrates without distorting the metal sheets. Adhesives are also capable of bonding dissimilar substrates. So where welding can only be used for metals, adhesives can be used for metals, plastic, glass, etc.
The structural adhesives used for adhesive bonding of aircraft structures are designed to have durable, stable, and long-lasting bonds under every condition. Epoxy structural adhesives usually have the highest bond strength. The amount of bond strength required for aerospace applications can vary from project to project, which can be customised by partnering with an adhesive manufacturer.
C] Factors To Consider Before Selecting Adhesives For Aerospace
- Bond strength: Selecting the adhesive with the desired bond strength is critical for safety. The adhesive needs to have the strength to withstand the pressure and keep the substrates bonded. Certain applications may require extremely high bond strengths while some may require the bond to be removable if necessary.
- Temperature tolerance: Aircrafts and satellites are usually subjected to extreme temperatures, both hot and cold. The adhesives need to have a wide range of temperature tolerance. There are several components which can get damaged when exposed to these temperatures, the structural adhesive should also be able to safeguard these components from such temperatures.
- Moisture resistance: Moisture resistance is a key factor to look out for when selecting an adhesive for aerospace applications. Aircraft and spacecraft are used in higher altitudes, where the moisture is very high as compared to the moisture at the ground level. Excessive moisture can interfere with the electronic components and cause rust.
- Chemical resistance: Neglecting chemical resistance can cause structural failure in case an incompatible chemical comes into contact with the adhesive. As adhesives are used to bond critical components like the wing and fuselage, adhesive failure can be catastrophic. Epoxy adhesives can be customised to resist a number of chemicals including acids.
- Curing time and method: Curing time is the time it requires for the adhesive to reach full strength. The curing method is how the adhesives reach there. Curing is an important step in getting the adhesive to the correct viscosity and adhesion. It is crucial to understand how to cure the adhesive and for how long.
- Cost: The cost of the adhesive might not be the most crucial factor for the safety and durability of the aircraft and spacecraft, but is a crucial factor for your organisation. When you are in the market looking for an aerospace adhesive, it is likely that you will have a budget in mind. Going over the budget can also have a significant impact on the finished product’s cost.
Conclusion
Adhesives are been used for aerospace applications for decades at this point. However, with the improvements in the adhesive technology, the applications and benefits of structural adhesives increased exponentially. Thus, choosing the right adhesives for your aerospace application becomes a critical task for the safety and structural integrity of the aircraft and spacecraft.
Make sure to conduct thorough research about the adhesive you choose for your project. You can get tailored epoxy adhesives for niche bonding, coating, and encapsulating applications. If you are currently looking for an adhesive manufacturer in India to get high-quality bespoke aerospace adhesives, contact us today! Our experts are always eager to help you find the right adhesive solution for your business requirements.
