From the Airbus A330 to the Boeing 787, practically all commercial aircraft are manufactured with riveted joints instead of welded joints. With riveted joints, two components are connected using a fastener known as a rivet. There are different types of rivets, including lap joints and butt joints. However, they are all used to permanently join two components together. Welding can also be used to join two components together.
Although welding has been around since the 1800’s and is an effective way to bond materials together, rivets have several advantages in the aircraft industry such as the ease of inspection, maintenance, and repeatability. The typical thickness of aircraft skin also makes it less appropriate for welds.
When rivets were very first invented they were forged by hand, the first machine capable of manufacturing steel rivets was invented in 1836 and rivets began getting used on aircraft in the 1920’s and 30’s. While rivet technology might seem simple, it has a lot of unique benefits that make it a great fit for aircraft design.
Aluminum Isn’t Tolerant of Heat
One reason that airplanes are manufactured with riveted joints instead of welded joints is because the aluminum materials used in their construction isn’t tolerant of heat. Most commercial aircraft are designed with an aluminum body. Not only is aluminum is inexpensive and readily available; it’s also lightweight. By using aluminum to construct airplane bodies, aerospace manufacturing companies can create lighter aircraft that are more fuel efficient than their counterparts made of other metals. But aluminum becomes weaker when exposed to heat, including the heat from welding, so most aerospace manufacturing companies prefer to connect joints using rivets.
Riveted Joints Are Stronger
The greatest benefit of using riveted joints in an aircraft is that they are stronger and more durable than welded joints. When two components are welded together, only the exterior of the components are joined together. On the other hand, using a rivet connects the two components from the inside, thus allowing for a stronger and more durable joint. This is particularly important for aircraft, as flying 550 mph at 30,000 feet above sea level places severe stress on the aircraft’s joints.
Riveted Joints Are Easier to Inspect
Riveted joints are also easier to inspect than welded joints. It only takes a quick visual inspection of a riveted joint to ensure that the two connected components are secure. With a welded joint, a machine or device must be used to test the joined components. There’s no easy or effective way to perform a visual inspection of a welded joint. Therefore, aerospace manufacturing companies use riveted joints to simplify both the production and maintenance process of their aircraft.
Even with riveted joints, some commercial aircraft still have some welded components. For the critical components of an aircraft’s body, though, rivets are preferred because of their ability to withstand extreme stress without breaking or otherwise succumbing to damage. It’s a safer and more effective way for aerospace manufacturing companies to build aircraft.
Specs of an Aircraft Grade Rivet
Just like all other components of an aircraft, the rivets that are used must be manufactured according to spec to ensure they can hold up to the load. Common rivets used include:
These are five grades of rivets that are readily available and capable of being used on aircraft. They are usually made from an aluminum alloy just like the body of the airplane; mild steel rivets are also used to join steel parts on the airplane, as well as the 5056 rivets that are made from magnesium alloy that is resistant to corrosion.
Why Not Use Screws for Assembling Aircraft?
So why not screws instead of rivets? The most important reason for using rivets instead of screws is because rivets can withstand vibration much better. Think about it; when a rivet is installed it expands to fill the hole.
When a screw is installed it is turned by its head and grips to the sides of the metal with its threads, that can easily come loose with constant vibration at high speeds. Rivets are also significantly lighter than screws, making them the perfect option in aircraft assembly.