What is Rivet?
A rivet is a mechanical fastener composed of a head-on one end and a cylindrical stem on another (called the tail) which has the appearance of a metal pin.
A rivet is a permanent mechanical fastening. Before installation, a rivet consists of a smooth cylindrical shaft with a head at one end and another end is called a tail. Rivets are non-threaded fasteners that are usually manufactured from steel or aluminum.
When installing, the rivet is placed in a punched or drilled hole, and the tail is upset, or bucked, so that it expands to about 1.5 times the original shaft diameter, holding the rivet in place. In other words, the pounding or pulling creates a new “head” on the other end by smashing the “tail” material flatter, resulting in a rivet that is roughly a dumbbell shape.
To distinguish between the two ends of the rivet, the original head is called the factory head and the deformed end is called the shop head or buck-tail. They consist of a preformed head and shank, which is inserted into the material to be joined, and the second head that enables the rivet to function as a fastener is formed on the free end by a variety of means known as a setting.
Riveting is a forging process that may be used power to fix the parts together by engrossing and fascinating by use of a metal part called a rivet.
How do Rivets Work?
When installed the rivet is either drilled, placed, or punched into a hole, afterwards the tail is then deformed, holding the rivet in place.
The rivet is deformed by pounding or smashing of the tail, which makes the material flatter and usually causes the tail to be expanded by about one and a half times the size of the stem’s original diameter. When finished the tail has the appearance of a dumbbell shape completing the riveted joint.
Riveting can create either lap or butt joints with a variety of different rivet configurations, including single, double and zig-zag formations.
What is Riveting Process?
Riveting is a forging process that may be used to join parts together by way of a metal part called a rivet. The rivet acts to join the parts through adjacent surfaces. A straight metal piece is connected through the parts. Then both ends are formed over the connection, joining the parts securely.
The metal work piece used to form the connection may be hollow or it may be solid. Rivets have many uses, such as in the construction and sheet metal industries.
How riveting is done?
A hole is drilled or punched in the plate needed to be riveted. The punching is a very cheap method in relatively thin plates. But for a thick-plate like pressure vessel works, punching is not suited, because it may injure the material around the punched hole. In such cases drilling is adopted to make a hole. Drilling also results more accuracy in location and size of holes.
The rivet hole usually 1.5mm larger than the diameter of the rivet. Remove all the burrs and chips at the region to get tight plate joint. The rivet is placed in the hole, then the tail is deformed (upset, or bucked), so that it tail portion expand about 1.5 times of it shank diameter.
In other words, the deformed tail create a new head, resulting the rivet hold plates tightly. The original head of the rivet is called factory head while the newly formed head is called shop head or buck-tail.
The riveting can be done manually by using a hammer/ bucking bar or it is done by using riveting machines like a pneumatic hammer. In hand riveting, the die set is placed on the tail and apply massive blow by hammer.
This causes the shank to expand, fill the hole in the die and create a shop head as shown in the above figure. In machine riveting, the die is a part of the hammer that is operated by hydraulic and pneumatic machines.
Material use in Rivets
The material of the rivets must be tough and ductile. They are usually made of steel (low carbon steel or nickel steel), brass, aluminum, or copper, but when strength and a fluid-tight joint are the main consideration, then the steel rivets are used.
Types of Rivet
There are Different Types of rivets:
- Solid/round head rivets.
- Semi-tubular rivets.
- Blind rivets.
- Oscar rivets.
- Drive rivets.
- Flush rivets.
- Friction-lock rivets.
- Split rivets
- Threaded rivets
- Self-Piercing Rivet
Blind rivets get their name from the fact that they can be completely installed from one side. Ideal for projects where access to the joint is limited to only one side. Blind rivets are available in standard, structural, closed end, and various other styles for a wide range of applications.
Blind rivets or break stem rivets, are tubular fasteners with a mandrel through the center. Blind rivets are inserted into drilled holes in the parts to be joined, and a special tool is used to draw the mandrel through the body of the rivet. The blind end expands, and the mandrel is snapped off.
Blind rivets, commonly referred to as “pop” rivets are tubular and are supplied with a nail-like mandrel through the center which has a “necked” or weakened area near the head. The rivet assembly is inserted into a hole drilled through the parts to be joined and a specially designed tool is used to draw the mandrel through the rivet.
Solid rivets are among the simplest, strong, most reliable, and oldest types of fasteners. These simple devices consist of a solid shaft with a head on one end; once installed, the headless end of a solid rivet is deformed with a hammer or rivet gun to hold it in place.
It having been found in archaeological findings dating back to the Bronze Age. Solid rivets consist simply of a shaft and head which are deformed with a hammer or rivet gun. Such rivets come with rounded (universal) or 100° countersunk heads.
A rivet compression or crimping tool can also deform this type of rivets. This tool is mainly used on rivets close to the edge of the fastened material since the tool is limited by the depth of its frame. A rivet compression tool does not require two people and is generally the most foolproof way to install solid rivets.
A drive rivet is a type of blind rivet with a short mandrel that protrudes from the head. Once the drive rivet is inserted into a hole, the mandrel is driven in with a hammer or other implement to flare out the end of the rivet that is inside the hole.
This is commonly used to rivet wood panels into place since the hole does not need to be drilled all the way through the panel, producing an aesthetically pleasing appearance.
They can also be used with plastic, metal, and other materials and require no special setting tool other than a hammer and possibly a backing block placed behind the location of the rivet while hammering it into place. Drive rivets have less clamping force than most other rivets. Drive screws, possibly another name for drive rivets, are commonly used to hold nameplates into blind holes.
Semi Tubular rivets
Semi tubular rivets are similar to solid rivets but contain a hole at the end of the rivet opposite the head. This hole causes the tubular portion of the rivet (around the hole) to roll outward when force is applied. Semi tubular rivets also require less force needed for application and assembly.
The force needed to apply a semi-tubular rivet is about 1/4 of the amount needed to apply a solid rivet. Tubular rivets are sometimes preferred for pivot points since the swelling of the rivet is only at the tail. The type of equipment used to apply semi-tubular rivets range from prototyping tools to fully automated systems.
Typical installation tools are handset, manual squeezer, pneumatic squeezer, kick press, impact riveter, and finally PLC-controlled robotics. The most common machine is the impact riveter and the most common use of semi-tubular rivets is in lighting, brakes, ladders, binders, HVAC ductwork, mechanical products, and electronics.
Split rivets are ideal for piercing through softer materials such as most woods, leather, and plastic. These are the standard “home repair” rivets. They have sawed or split bodies with sharp ends to make their own holes through leather, fiber, plastic, or soft metals. They are not used in critical applications.
Threaded inserts and rivet nuts provide a uniquely strong permanent thread through sheet materials and other materials where installation is only possible from one side.
Threaded Rivets has a threaded internal mandrel (stem) with the external portion machined flat on two sides for the tool to grip and rotate. The head is normally hexagonal to prevent rotation of the tubular body while the mandrel is being torqued and broken off.
Oscar rivets are similar to blind rivets in appearance and installation but have split along the hollow shaft. These splits cause the shaft to fold and flare out as the mandrel is drawn into the rivet. This flare provides a wide bearing surface that reduces the chance of rivet pull-out. This design is ideal for high vibration applications where the back surface is inaccessible.
A version of the Oscar rivet is the Olympic rivet which uses an aluminum mandrel that is drawn into the rivet head. After installation, the head and mandrel are shaved off flush resulting in an appearance closely resembling a brazier head-driven rivet.
A flush rivet is used primarily on external metal surfaces where good appearance and the elimination of unnecessary aerodynamic drag are important. A flush rivet takes advantage of a countersink hole; they are also commonly referred to as countersunk rivets.
Countersunk or flush rivets are used extensively on the exterior of aircraft for aerodynamic reasons such as reduced drag and turbulence. Additional post-installation machining may be performed to perfect the airflow.
These resemble an expanding bolt except the shaft snaps below the surface when the tension is sufficient. The blind end may be either countersunk (‘flush’) or dome-shaped.
One early form of the blind rivets that was the first to be widely used for aircraft construction and repair was the Cherry friction-lock rivets. Originally, Cherry friction-locks were available in two styles, hollow shank pull-through, and self-plugging types. The pull-through type is no longer common; however, the self-plugging Cherry friction-lock rivet is still used for repairing light aircraft.
Friction-lock rivets cannot replace solid shank rivets, size for size. When a friction-lock is used to replace a solid shank rivet, it must be at least one size larger in diameter because the friction-lock rivet loses considerable strength if its center stem falls out due to vibrations or damage.
Self-pierce riveting (SPR) is a process of joining two or more materials using an engineered rivet. Unlike solid, blind and semi-tubular rivets, self-pierce rivets do not require a drilled or punched hole.
SPRs are cold-forged to a semi-tubular shape and contain a partial hole to the opposite end of the head. The end geometry of the rivets has a chamfered poke that helps the rivet pierce the materials being joined. A hydraulic or electric servo rivet setter drives the rivet into the material, and an upsetting die provides a cavity for the displaced bottom sheet material to flow.
The self-pierce rivet fully pierces the top sheet material(s) but only partially pierces the bottom sheet. As the tail end of the rivets does not break through the bottom sheet it provides a water or gas-tight joint. With the influence of the upsetting die, the tail end of the rivet flares and interlocks into the bottom sheet forming a low-profile button.
What is Rivet Joint?
Riveted joint is permanent joint with mainly two components (parts to be joined) which are held together by a rivet with the head at top and tail at the bottom.
Riveted joints are very similar to bolted joints though rivets pierce through CFRPs and partly to aluminium alloys in the bottom and flare inside aluminium alloys with the help of a die to generate the bonding.
Types of Riveted joint
Following are the two types of riveted joints: lap-joints and butt-joints depending upon the way in which the plates are connected.
In lap joints the components to be joined overlap each other. Lap joints can be used to join wood, plastic, or metal. A lap joint can be used in woodworking for joining wood together. A lap joint maybe a full lap or half lap.
In butt joints an additional piece of material is used to bridge the two components to be joined which are butted up against each other. The name ‘butt joint’ comes from the way the material is joined together.
A butt joint is that in which the main plates are kept in alignment butting (i.e. touching) each other and a cover plate (i.e. strap) is placed either on one side or on both sides of the main plates. The cover plate is then riveted together with the main plates.
Butt joints are classified into the following types:
- Single strap butt joint, the edges of the main plates butt against each other and only one cover plate is placed on one side of the main plates and then riveted together.
- In a Double strap butt joint, the edges of the main plates butt against each other and two cover plates are placed on both sides of the main plates and then riveted together. And In addition to the above, the following are the types of riveted joints depending upon the number of rows of the rivets.
- Chain riveted joint In this type accommodated rows of rivets may lie exactly opposite to each other over straight lines.
- Zig Zag Riveted Joint Unlike the above type, here the rows may appear staggered and not complementing each other.
- Diamond Riveted Joint You will find this type of joint typically in butt joints. here the rivets are arranged in rows which are broader at the butt ends and taper out at the opposite edges forming quite the shape of a diamond.
Application of riveted joints
These are some applications of Riveted joints:
- Rivet joints are permanent joints used mainly for fastening sheets and shaped rolled metal.
- Used for aircraft structure where Aluminum is used.
- It’s used in the manufacturing of bus and trolleybus bodies to create a heavily loaded joint
- Used for metals that have poor weldability.
- Used for heterogeneous materials like asbestos friction lining and steel.
- It is used where we have to avoid after thermal effects, as in the case of welding.
- Welded joints have poor vibration damping capabilities so where required rivets are used in place of it.
- They are used in lap, abutment, and double-cover plate joints.
- It has lightweight, much cheaper, and high strength.
- They can still be used for constructing a metal bridge, hoisting cranes, boilers, and pressure tanks. But some other joining process may serve better.
- In essence, rivets are widely used to join components in aircraft, boilers, ships, and boxes as well as other enclosures.
Advantages and Disadvantages of Riveting
Benefits of Riveting
- Relatively inexpensive method. The production of the rivet is cheap.
- The rivet can be used in the joining of ferrous as well as a nonferrous metal like aluminum and copper alloys.
- The rivet can be used in the joining of nonmetallic material like wood, plastic, asbestos sheet, etc.
- One of the main advantages of the rivet is that it can use to join dissimilar materials. (e.g.: joining aluminum plate and copper plate).
- Ability to make joint regardless of the location. (Vertical, overhead, etc.)
- No fumes and gases produced as in the welding; the production is environmentally as well as user-friendly.
- Riveted joints are reliable than other methods in applications where the joint subjected to excessive vibration and impact forces.
- High shear strength, good fatigue resistance.
- Aluminum rivets are lighter than bolts and screws. They also possess high resistance to atmospheric and chemical corrosion.
- Since there is no melting of metal and uneven heating and cooling involved while the joining process, thermal effects on the riveted joints are minimum. So, it causes little or no damage to protective coatings of material.
- The quality inspection of the riveted joint is easier than the welding inspection.
- Dismantling of the riveted joint causes less damage when compared to the welded joint.
Limitations of riveting
- Riveting take more labor time than welding. Additional operations like the layout and drilling holes are necessary. The labor cost of rivet joints is high.
- Stress concentration at the rivet holes of metal plates.
- The holes may weaken the working cross-section of the plate. Then the additional thickness is required to compensate for this problem. This additional thickness and overlapping of plates for riveting increase metal consumption.
- It has more weight than a welded joints due to strap-plate and rivets.
- The riveted joints are bulkier than welding and brazing. The projection of rivet also affects aesthetic appearance.
- They typically do not make a tight or leak-proof joint unless using hot rivet or sealant along with the rivets.
- The riveting process is noisier than welding due to hammer blowing.
Types of failures in Riveted Joints
- Shear failure
- Tensile failure of plates
- Crushing failure of plates
- Shear failure of plates in the margin area
- Tearing of plate in the margin area
A rivet is a mechanical fastener composed of a head-on one end and a cylindrical stem on another (called the tail) which has the appearance of a metal pin.
Types of rivets:
1. Solid/round head rivets.
2. Semi-tubular rivets.
3. Blind rivets.
4. Oscar rivets.
5. Drive rivets.
6. Flush rivets.
7. Friction-lock rivets.
8. Split rivets
9. Threaded rivets
10. Self-Piercing Rivet
There are two main types of riveted joint: lap-joints and butt-joints. In lap joints the components to be joined overlap each other, while for butt joints an additional piece of material is used to bridge the two components to be joined which are butted up against each other.
1: to fasten with or as if with rivets. 2: to upset the end or point of (something, such as a metallic pin, rod, or bolt) by beating or pressing so as to form a head. 3: to fasten or fix firmly. 4: to attract and hold (something, such as a person’s attention) completely.
Rivet definition is a headed pin or bolt of metal used for uniting two or more pieces bypassing the shank through a hole in each piece and then beating or pressing down the plain end so as to make a second head. rivet. verb. riveted; riveting; rivets.