What are Rivets and Riveted joints? - Types and How it Works

Riveting is a permanent cold-joining process that is widely used in the manufacturing world. It’s the best alternative and more economical than welded and glued joints.

Before the wide use of welding, riveting was the main joining method used in the construction of metal bridges, boilers (tight stress-relieved to tight strong joints), low-pressure tanks (requiring tight joints), and hoisting cranes (strong joints or stress-relieving).

The primary applications of Rivet’s joints are permanent joints used mainly for fastening sheets and shaped rolled metal. Well, in this reading, we’ll explore what rivets, riveting, and riveting joints are, their applications, diagrams, operations, and how they work. We’ll also explore the advantages and disadvantages of riveted joints.

Let’s get started!

What are Rivets, Riveting, and Riveted Joints?

Rivets are non-threaded fasteners usually made of steel or aluminum used in joining pieces of metal to another. They comprise of preformed head and shank, which is put into the material or pieces to be joined.

Rivets are permanent mechanical fasteners with the appearance of a metal pin. They are used to join large structural members, usually sheet metals.

Rivet’s joints are carried out with a rivet pin and gun, and the operation is called riveting. Although there are types of rivet guns and pins, depending on the application.

Rivets are categorized as fasteners their second head is formed on the free end by a variety of means that is called setting. Rivets can be made from any ductile material like carbon steel, aluminum, and brass. However, a variety of coating is done to improve corrosion resistance.

Serious consideration needs to be made while selecting material and coating to prevent the possibility of corrosion by galvanic action. Note that a given-size rivet will not be as strong as the equivalent threaded fastener.

In its working, the rivet is placed in a drilled hole with the tail upset so that it can expand to the original shaft diameter. This will cause the rivet to be hold in place.

New head is created when pounding or pulling of the tail occur using rivet gun. The material then flatter resulting in a riveted joint. The new head of the rivet is known as buck-tail or shop head while the original head is called factory head.

The head formed at each end of a rivet joint after installation support tension load of the application. Rivet joint are also capable of handling shear loads.

Applications of Rivet Joints

Below are the applications of rivet joints:

Rivet’s joints are permanent joints used mainly for fastening sheets and shaped rolled metal.
They are used in lap, abutment, and double-cover plate joints.
They can still be used for constructing a metal bridge, hoisting cranes, boilers, and pressure tanks. But some other joining processes may serve better.
Rivet’s joints are used to join materials that cannot be welded or heated, such as thin-walled parts made of sheet material in aircraft construction.
It’s used in the manufacturing of bus and trolleybus bodies to create a heavily loaded joint
In essence, rivets are widely used to join components in aircraft, boilers, ships, and boxes as well as other enclosures.
Rivet joins are used in traditional wooden boat, copper nails, and clinch bolts.

Rivet is widely used because it’s much cheaper to install than other joining processes. The advancement of technology has brought about the automated riveting machine, which is capable of installing more than a thousand rivets in an hour.

Diagram of rivet Joints

Types of Rivets

Below are the various kinds of rivets:

Drive rivets: are types of rivets with short mandrel and is driven with a hammer so that the end inserted into the hole will flare.

Blind rivets: also known as hollow or pop rivets, used when it’s impossible to access the other side of the application. These types of rivets are often used in electronics shipbuilding, and aerospace because the process is fast and effective.

Oscar rivets: are similar to blind rivets but have splits along their hollow shaft. The shaft comes in three set causing the shaft to bend and flare outwards when the mandrel is drawn into the rivet. A wide surface is created when the flare is drown, which reduces the change of the rivet from pulling.

Friction-lock rivet: have countersunk and dome shape. They are blind rivet that are widely used in aerospace applications and they look like an expanding bolt.

Flush rivets: are used for external surfaces as they offer good appearance and eliminate aerodynamic drag. These types of rivets have countersunk heads and a countersunk hole which is why they are also called countersunk rivets.

Round head rivets: these are the oldest types of rivets and the most reliable kind. They are also called solid rivets due to their strength and capability.

Self-piercing rivets: are kinds of rivets that do not require drilling or punching to perform the rivet joint. They have chamfered poke that pierce materials as they go through the top sheet of material. They do not fully pierce the bottom sheet, creating a water or gas-tight joint.

Structural steel rivets: are types of rivets used mostly on structural steels, although they have been replaced by high-strength bolts.

Button head rivets: Button head types of rivets are used to join parts where projecting heat does not disturb or obstruct the working of the application. They are suitable for fixed and close joints, because of the close clamping effect they offer.

Countersunk-head rivets: The countersunk-head rivets are used to join parts whose surfaces are uneven by projecting rivet heads. They are not suitable for highly stressed connections. Their tapered head enters the joint, showing their surfaces.

Oval head countersunk rivets: The overhead types of countersunk rivets are used to join parts with rough and uneven surfaces. In such an application, the requirement for a high-quality surface is excluded, because an uneven surface will be achieved.

Boiler construction rivet: Boiler construction rivets consist of button head rivets with conical shank. This makes it easy to accurately get into unaligned boreholes. This rivet is often used in the construction of boilers and pressure vessels. Close and fixed connections are achieved when the plate edges and rivet heads undergo caulking.

Explosive rivets: Explosive types of rivets are used on applications where is joining process can be accessed from one side. These include aircraft manufacture of light metal construction. The rivets are electrically ignited are the shank which will explode and widen it.

Belt rivet: A belt rivet is used for connecting soft materials like leather, felt, rubber, etc.

Pin: Pins are used in precision mechanics as their projecting end acts like the shank of a rivet.

Types of Riveted Joints

Below are the types of riveted joints:

Lap joint: in a lap joint, the working plates overlapped each other, and the rivets are inserted into the overlapped region.
Butt joint: butt joints are types of riveting where the plates to be joined are kept in alignment butting or toughing without overlapping. An external plate is also used to cover one side or both sides of the main plate, which is also riveted with the main plate. This joint can cost much, but some applications require it.
Single strap butt joints: in this type of butt joint, only one cover plate is placed on the main plate.
Double strapped butt joint: two cover plates are used in this type, each one on both sides of the joint.
Single riveted joint: there is only one row in a lap joint. A butt joint can also have one row of rivets on each plate.
Double riveted joint: in double riveted joints two rows of rivets are used in a lap joint or two rows of rivets are used in each main plate of butt joints.
Chain riveted joint: in these types of joints, the rivets in the adjacent rows are opposite to each other (in the same transverse line).
Zigzag riveted joint: in zigzag riveted joints, the rivets in adjacent rows are not in chain arrangement.

How Does Rivets or Riveting Works?

In riveted joint, permanent joint are created with two main component, parts to be joined and the rivet itself. The part to join are held together by the rivet pins with the head at the top and the tail at the bottom.

The mechanical fastener is designed with a plane unthreaded shaft that enters through holes to join the part together. The riveting is perform using riveting gun and it forms head at each end preventing the rivet from moving or being removed. The shaft help to achieve this.

The type of rivet used will determine its ability to support shear load, and how much it will resist considerable forces. Rivets functions similarly to nut and bolt, but they are not permanent as rivets.

Just as earlier mentioned, rivets has pre-formed head at one end, known as factory head. The other head is form after the insertion which is called shop head.

The factory head look like the the head of a bolt while the shop head is like a nut. The nut like head forms a temporary head at the other end. This shop head is also called tail or rivet’s shaft. Also the forming operation of the tail is called upsetting or buckling.

Riveting Operations

Below is the step-by-step riveting operations:

Clamping/drilling:

Clamping and drilling are the first operations to be carryout while creating rivet joints. The plates to be joined are clamped with one another tightly as possible to prevent space in between. It’s then drilled together to ensure there are no misaligned holes. But if there is, it should be read by a structural reamer. Rivet holes must be drilled with a little larger diameter of the rivet shank.

Deburring/countersinking:

The next operations to be considered while creating rivet joints deburring or countersinking. A Countersinking cutter is always used to debar the rivet holes using a 75° countersinking cutter.

Inserting/setting

This is when the rivet pin will be inserted into the borehole in the workpieces. With the blow of a hammer or rivet gun on the rivet setter, the plates are pressed together as the setter head compresses to the workpiece.

Upsetting:

Upsetting is performed in riveting operation by a couple of hammer blows accurately in the direction of the longitudinal axis until the borehole is filled up.

Performing/heading:

Performing is a steady blowing or hitting around the rivet head so that a button head is created.

Heading:

With the countersunk-head types of rivets, the rivet head can be driven into the countersinking immediately by the heading operations.

Finish-forming of the button closing head:

With sufficient preform riveting operations on the closing head, the rivet header is finish-formed by the rivet header.

In essence, riveting by hand is performed in cold conditions, if the steel rivet up to about 8mm in diameter. However, thicker rivets are to be done in red-hot conditions. Non-ferrous metal rivets are also worked in cold conditions after undergoing an anneal process.

Materials become hard and brittle on all cold working of steel or non-ferrous metals, especially if the riveted joints are formed by many hammer blows. Keeping these materials as tough and elastic as possible, few and well-aimed blows will be employed when creating the joints.

Riveting/Rivet Joints Tools

Below are the different types of tools used for riveting operations:

Riveting hammer:

One of the greatest riveting tools is the hammer. Locksmith’s hammers are the ones used here and it weighs between 50g and 200g while hand hammers weigh between 200g and 400g. engineers also make good use of this hammer.

Rivet setter:

A rivet setter is used for setting the set head to the workpiece and also use for pressing the plates to be riveted toward each other. the head bore is made of hard material.

Rivet header:

The header looks much like the setter but is used for a different purpose. The header is used for finish-forming the closing head of button head types of rivets after it had been pre-shaped using a hammer. The head recess is hardened and polished leaving it with a good appearance.

Rivet support (counter holder):

Rivet supports are special types of riveting tools that receive the set head of a button head rivet. It is equipped with a head recess. Some fixed rivet supports are available for clamping in a vice, and some are even designed to be adjusted.

Clamping tools:

Clamping riveting tools are also called clamp dogs as they are used to press the plates together using their teeth. Rivet pins are performed when a round material is a clamp.

The following are the riveting tools required while performing hot rivets:

Smith’s fire – it is used for heating the rivets.
Rivet clamp – used for holding the hot rivets.
Rivet tongs – is for taking the rivets out of the fire.

Mechanized riveting used the following equipment:

Hydraulic Riveter
Pneumatic Riveter

Advantages of Riveted Joints

Below are the benefits of a riveted joint:

Riveting is an inexpensive method of joining. That is, the production of a rivet is cheap.
Both ferrous and non-ferrous metals can be joined with riveting
Riveting can be done on non-metallic materials like wood, plastic, asbestos sheet, etc.
Dissimilar material can be joined with rivets e.g. joining aluminum plate with copper plate
There is the ability to make joints regardless of the location (vertical, overhead, etc.)
Not hazardous as gas and fumes are not produced as in welding.
The joining process is environmentally and user-friendly.
Riveted joints serve well and are more reliable in applications where the joint is subjected to vibration and impact forces.
Good fatigue resistance and high shear strength.
It serves well on lighter applications since bolts and screws can be weightier.
Riveted joints also posse’s high resistance to atmospheric and chemical corrosion.
The thermal effect is minimum since there is no melting of metal and uneven heating and cooling. The causes little or no damage to the protective coatings of the material
Unlike welding inspection, it’s easier to perform on riveted joints.
Dismantling riveted joints causes less damage compared to welding or other methods.

Disadvantages of Riveted Joints

Below are the limitations of riveted joints:

Riveting takes more labor time than welding. This is because additional operations like drilling, countersinking, etc. are required.
The labor cost of riveting is high.
Holes in the joint may weaken the cross-section of the plates.
Stress concentration at the rivet holes of metal plates.
It has more weight than welded joints due to strap plates and rivets.
The joint is bulkier than other methods like welding and brazing.
The projection of rivets also affects aesthetic appearance.
Typically, riveted joints do not make tight or leak-proof joints only if hot riveting is done or sealant along with the rivet which will cost more.
The operation is noisier than welding due to the blowing sound of the hammer.

Share with others!

What are Rivets and Riveted joints? – Types and How it Works