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).
Today we’ll be looking at the definition, applications, components, diagram, types, operations, and tools used for riveting and riveted joints. You’ll also get to know the advantages and disadvantages of the joints.
- 1 What are rivets?
- 2 Applications of rivet joints
- 3 Types of rivets
- 4 Types of riveted joints
- 5 Riveting operations
- 6 Riveting/rivet joints tools
- 7 Advantages and disadvantages of riveted joints
- 8 Conclusion
What are rivets?
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. Rivet joints are carried out with a rivet pin and gun, and the operation is called riveting. Although there are types of rivet gun and pin, depending on the application.
Rivets are categorized as fasteners are its second head is formed on the free end by a variety of means that is called setting. See an illustration of a conventional rivet before and after setting in the figure below.
As earlier mentioned, 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.
Applications of rivet joints
Below are the applications of rivet joints:
Rivet 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 process may serve better.
Rivet 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 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.
Read more: Working Principle of Friction Welding
Types of rivets
Below are the various types of rivets:
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.
The countersunk-head rivets are used to join parts which its surfaces are uneven by projecting rivet heads. They are not suitable for highly stressed connections. Their tapered head enters into the joint, showing their surfaces.
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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 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.
A belt rivet is used for connecting soft materials like leather, felt, rubber, etc.
Hollow rivet or tubular rivet:
Hollow or tubular types of rivets are used when joining delicate materials. Little force is required during the operation, this makes it less tedious.
Pins are used in precision mechanics as its projecting end acts like the shank of a rivet.
Read more: 5 different types of welding Joints
Types of riveted joints
Below are the types of riveted joints based on their classifications:
Types of riveted joint depending on how the riveted plates are placed are classified into two:
Lap joint: in a lap joint, the working plates overlapped each other, 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.
Types of riveted joints based on the number of cover plates used. Butt joints are further divided into two; single strap butt joints and double strapped butt joints.
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.
Diagram of a rivet:
Types of riveted joints based on how many rows of rivets in 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.
Note, there are triple and quadruple riveted joints similar to the above-explained ones.
Types of riveted joints based on the arrangement of adjacent rows of rivets:
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.
Below is the step by step operations carry during riveting:
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 ream by a structural reamer. Rivet holes must be drilled with a little larger diameter of the rivet shank.
The next operations to be considered while creating rivet joints deburring or countersinking. A Countersinking cutter is always used to debarred the rivet holes using a 75° countersinking cutter.
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 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.
Preforming is a steady blowing or hits around the rivet head so that a button head is created.
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 condition, if the steel rivet up to about 8mm in diameter. However, thicker rivets are to be done in red-hot conditions. Non-ferrous metals 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.
Watch the video below to learn how rivet joints or riveting is done:
Riveting/rivet joints tools
Below are the different types of tools used for riveting operations:
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.
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.
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.
Read more: Understanding Soldering process
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 and disadvantages of riveted joints
Below are the benefits of a riveted joint in their various applications:
- 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 joint regardless of the location (vertical, overhead, etc.)
- Not hazardous as gas and fumes are not produce as in welding.
- The joining process is environmentally and user friendly.
- Riveted joints serve well and more reliable on 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 bolt and screw 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 protective coatings of the material
- Unlike welding inspection, it’s easier to perform on riveted joints.
- Dismantling riveted joint causes less damage compared to welding or other methods.
Read more: Power-feed and hand-feed drilling machine
Despite the advantages of riveted joints some limitations still occur. below are the disadvantages of riveted joints in their various applications:
- 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 of 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-plate and rivets.
- The joint is bulkier than other methods like welding and brazing.
- 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.
Read more: Components of drilling machine
Among the joining process today, riveting tends to be one of the common and most performed types as serves well on different applications. In this article, we’ve examined the definition, applications, functions, components, diagrams, types, operations, and tools used for riveting and riveted joints. We’ve also explained the advantages and disadvantages of the rivet joints.
I hope you enjoyed the reading, if so, kindly comment on your favorite section in this article. And please don’t forget to share with other technical students. Thanks!