Aircraft Rivets

The structure of an aircraft are constructed by joining metal sheets together, and this is often done with solid shank Aluminum-alloy rivets. When a rivet is made, it resembles a metal pin with a formed head on one end. A hand or pneumatic tool upsets (deforms) the rivet's shank after it has been inserted into a drilled hole. The second head, which can be produced manually or with pneumatic tools, is referred to as a "shop head."

Like a nut on a bolt, the shop head serves the same purpose. Rivets are used to join spar sections, hold rib sections in place, secure fittings to various parts of the aircraft, and fasten countless bracing members and other parts together in addition to joining aircraft skin sections. A bond formed by the rivet is at least as durable as the materials being joined.

The common solid shank type, which requires the use of a bucking bar, and the special (blind) rivets, which can be installed in situations where a bucking bar cannot be used, are two of the main types of rivets used in aircraft.

Hardware store rivets are not used in aircraft. Hardware store rivets should never be used in place of rivets of aeronautical quality. The materials used to make the rivets might vary substantially, as can the strength and shear strength characteristics of the rivets. Hardware store countersunk rivets feature 78° angle heads, whereas aircraft countersunk rivets have 100° angle heads for greater surface contact to hold it in place.

Compared to rivets made for ordinary use, aircraft rivets are produced to significantly higher standards and requirements. Different manufacturers had various rivet head designs when aeroplane manufacturers began producing all-metal aircraft in the 1930s. There were 78° countersunk heads, button heads, mushroom heads, modified brazier heads, and brazier heads. Four rivet head designs largely replaced all the others as aircraft standardized. The most common types of rivets used for airflow exposure are universal head MS20470 or 100° countersunk head MS20426 rivets. The flathead MS20442 and roundhead MS20430 are typically used for rivets in internal structures.

Ice Box Rivets

A solid shank aircraft rivet made of 2017-T or 2024-TAluminium-alloy are known as Ice box rivets, are annealed and must be kept refrigerated until they are to be driven. These rivets are too hard to drive in the condition they are received from the manufacturer without heat treatment. On receipt from the manufacturer, these rivets are heat treated to make it soft and, thereafter, quenched in water. These rivets are then kept in a refrigerator/ icebox until they are ready to be used.

In Aluminuim-alloy structures when higher strength is required than can be achieved with the same size 2217-T rivet, the 2017-T and 2024-T rivets are employed. After being removed from refrigeration, the 2017-T rivet should be driven in about an hour and the 2024-T rivet in about ten to twenty minutes.

Particularly with aluminum-alloy rivets, metal temper plays a significant role in the riveting process. The heat-treating properties of aluminum-alloy stock and rivets are identical. They can undergo the similar annealing and hardening processes as aluminum. Before a nice head may form, the rivet must be soft or rather soft. Prior to driving, the 2017-T and 2024-T rivets are annealed. Age makes them harder.

Similar to heat treating (annealing) stock, rivets are treated in a similar manner. It is necessary to use an electric air furnace, a salt bath, or a hot oil bath. Depending on the alloy, the heat-treating temperature ranges from 625 °F to 950 °F. Rivets are heated in a wire basket or tray for easy handling. After being heat treated, they are promptly quenched in cold water (70 °F).

The heat-treatable 2017-T and 2024-T rivets start to age harden within a few minutes of exposure to ambient temperature. They must therefore be put in cold storage if not used right once after quenching.

Refrigeration is the most popular method for preserving heat-treatable rivets at low temperatures (below 32 °F). "Icebox" rivets are the name given to them. They can be kept in this storage situation for up to two weeks and still be soft enough to drive on. Any rivets that aren't used within that time frame need to be taken out for reheat treating.

After driving, icebox rivets reach roughly half of their maximum strength in about an hour, and their full strength in about four days. 2017-T rivets must need reheat treatment if they are left at room temperature for more than an hour. This also holds true for 2024-T rivets that have spent longer than 10 minutes at room temperature.

An icebox rivet should never be mixed with rivets that are still in cold storage after it has been removed from the refrigerator. If you take out more rivets from the fridge than you can use in 15 minutes, store the extra ones for reheating in a different container. If done correctly, heat treating rivets can be done repeatedly.

Types of aircraft rivets

The three types of rivets that are most frequently used are mechanically expanded, blind, and solid shank rivets. Nonstructural type self-plugging (friction lock) rivets and pull-through rivets, also known as mechanical lock—flush fracturing, self-plugging rivets, are two classes of mechanically expanding rivets.

Solid shank rivets

Generally, solid shank rivets are used for repairs. Their type of head, size of shank, temper state, and type of material from which they are produced are all used to identify them. The cross-sectional shape of the head determines the name of the solid shank rivet head type, such as universal head, roundhead, flathead, countersunk head, and brazier head. Special marks on the rivet head identify the temper designation and strength. The majority of aviation solid shank rivets are made of aluminum-alloy.

For riveting buildings made of aluminium-alloy, the 2117-T rivet, also referred to as the field rivet, is most frequently employed. The field rivet is highly sought after since it can be used right away and doesn't require any additional heat treating or annealing. It also has a high level of corrosion resistance properties.

Blind Rivets

There are numerous locations on an aeroplane where it is hard to access both sides of a riveted structure or structural component or where there is not enough room to employ a bucking bar. Furthermore, the entire strength of solid shank rivets is not required for the connection of various nonstructural components, such as flooring, deicing boots, and other interior furnishings for aircraft.

Special rivets that can be bucked from the front have been created for use in such locations. Special rivets can be lighter than solid shank rivets while yet being extremely strong for the intended application. These rivets are made by a variety of manufacturers and have distinctive qualities that call for special removal tools, special removal techniques, special installation techniques, and special removal techniques. They are known as unique rivets for this reason. These rivets are also known as blind rivets because they are frequently placed in areas where one head (typically the shop head) cannot be seen.

Self-Plugging Rivets (Friction Lock)

The friction lock self-plugging blind rivets are produced by a variety of companies. All of them share the same fundamental information regarding their production, composition, uses, selection, installation, inspection, and removal processes.

A rivet head with a hollow shank or sleeve and a stem that extends through the hollow shank are the two components that make up self-plugging (friction lock) rivets.

When a pulling force is applied to the stem of the rivet, several things happen in the right order:

The stem of these rivet is pulled into the rivet hollow shank.
The mandrel portion of the stem forces the rivet shank to expand into the hole.
When friction (or pulling force) becomes great enough, it causes the stem to snap at a breakoff groove on the stem.

Since the plug section (bottom end of the stem) is kept in the rivet's shank, it has a far higher shear strength than a hollow rivet would

The two most popular head designs for self-plugging (friction lock) rivets are a protruding head like the MS20470 or universal head and a 100° countersunk head. From some manufacturers, you can choose from several head shapes.

The upper portion of the stem of the self-plugging (friction lock) rivet may be a knot, knob, or it may be serrated.

Rivets that self-plugging (or friction lock) are made of various materials. In addition to stem 2017 Aluminum-alloy and sleeve 2117T Aluminium-alloy, stem 2017 Aluminium-alloy and sleeve 5056 Aluminum-alloy, and stem steel and sleeve steel, rivets are also available in the following material combinations.

Self-plugging (friction lock) rivets are created so that only one person is needed for installation; access from both sides is not required. Because of the rivet stem's superior pulling power, a consistent work can always be guaranteed. Self-plugging (friction lock) rivets can be used to attach assemblies to hollow tubes, corrugated sheet, hollow boxes, and other materials because access to the opposite side of the work is not required. The rivet can be used to fasten assemblies to plastic or plywood because hammering is not required for its installation.

Pull-Thru Rivets

The pull-thru blind rivets are made by a number of businesses. All of them share the same fundamental information regarding their production, composition, uses, selection, installation, inspection, and removal processes. Two components make up pull-thru rivets: a rivet head with a hollow shank or sleeve and a stem that extends through the hollow shank.

When a pulling force is applied to the stem of the rivet, several things happen in the right order:

The stem of these rivet is pulled through the rivet hollow shank.
The mandrel portion of the stem forces the shank to expand forming the blind head and tightly filling the hole.

Two common head designs are produced for pull-thru rivets: a 100° countersunk head and a projecting head like the MS20470 or universal head. From some manufacturers, you can choose from several head shapes.

There are various materials used to make pull-thru rivets. The most widely utilized materials are Monel, 5056 aluminum-alloy, and 2117-T4 aluminum-alloy. Pull-thru rivets are made to be installed by just one person; access from both sides of the work is not required.