In the production process, most devices or parts are normally made up of more than one part being attached together. Fasteners play the role of joining the various parts together. A rivet can be described as a metallic bolt or fastener that is used to join two metals together. It is made up of a head and a tail each on its two sides. Rivets are usually made of different materials and in different sizes in regards to the areas where they are to be applied. In today’s life, rivets have proven to be very important in the manufacturing process and they are mostly utilized by a number of industries. Some of the examples of where rivets are applied include in the manufacture of boats, aircrafts, jewelry, and automotives. Rivets have become popular in the manufacturing industries because of the many benefits that come with them and also their efficiency. In this article, we are going to discuss features of rivets, their types, and their applications in detail.
II. Types of Rivets
There are various types of rivets used in industries. They are, however, grouped into specific categories as explained below.
A. Solid rivets
These are considered to be the oldest and the most regularly used kind of rivets. On one end of the solid rivet, there is usually the head whereby after installation the other side is usually hit and deformed using a rivet gun or hammer till it is deformed. The deformed nature of the other end helps to ensure that the rivet stays in place. In instances where there is a need for one to ensure safe and dependable products, solid rivets are the best choice. In most cases, aluminum is used to make solid rivets. The aircraft industry is an example of industries that finds solid rivets very crucial in the manufacture of various parts.
B. Tubular rivets
These kinds of rivets are usually made of a head and a hollow part each on one side of the rivet. The hollow part usually plays a crucial role in connecting two parts being joined together. Cold working being the method used to create the hollow part of the rivets, it is necessary for the metals used to have high ductility and low strength. The tubular rivets are further divided into various groups which include:
- Full tubular rivets are preferably used on soft materials such as plastic due to their weak nature as compared to semi-tubular rivets. The holes in them are usually deeper than the other tubular rivets.
- Compression tubular rivets which are also used on soft materials. They are mostly used during the manufacture of handbags, clothing, luggage, and textiles. They are usually made up of two parts which are the cap and stem which are easy to fix and are useful in the fastening of different materials.
- Semi-tubular rivets which contain the hollow part in the field end and usually seem more like solid rivets. These are commonly used in joints that experience motion such as in breaks, and ladders among others.
C. Blind rivets
These metallic fasteners are usually tube-like and have a mandrel at the center. The parts that are to be attached contain holes where the blind rivets are put to connect them. As the name suggests, the blind rivets can be installed from just one side of a part leaving the other side “blind”. This makes them be used mostly in joining parts whose the back side of the joint cannot be seen. It is the most used rivet in the manufacturing of ships, aerospace, and electronics. This category comprises several kinds and they are:
- Threaded rivets. This is a fastener that is considered a form of the standard rivet. It is mainly used in connecting parts that are of high performance.
- Pull-mandrel rivets. They are in most cases used in the electronic industry and instances where high rigidity is required. It is used when cliches are needed on two flush surfaces on the two sides of the rivet.
- Drive-pin rivets. These types of rivets are in most instances used in architecture and aesthetic applications. They have mandrels that are short projecting on their heads which are worked on by a hammer once the rivet is inserted in a hole in the parts to be joined. This leads to the widening of the part of the rivet inserted in the hole. Their clamping force is usually low compared to other rivets.
D. Split rivets
These types of rivets also known as bifurcated rivets are best suited to connect materials that are softer such as plastic and leather. They are usually designed to split on one end and are sharp enough at the ends which helps them to make holes in the materials that they are joining together. It is advisable to use them only on simple applications.
E. Flush rivets
These are used on outer surfaces to boost the appearance of an object and to get rid of aerodynamic drag which affects the motion of a moving automobile or aircraft. These kinds of rivets can also be referred to as countersunk rivets whereby their countersunk heads and holes make them suitable for their roles.
There are also friction lock rivets and self-piercing rivets which are also categories of rivets.
III. Materials Used in Rivets
Manufacturing companies use various materials in the manufacturing of rivets to satisfy the needs of both the manufacturers and customers. The different materials help diversify the uses of the rivets. These materials include the following:
A. Aluminum rivets
Aluminum is on the other hand used due to its high level of gentleness and lightness. Rivets made from aluminum are usually used in a number of applications due to the fact that they do not degrade easily. Aluminum is also preferred due to its high ductility which makes it easier for it to be used in a number of applications and where the manufacture of various complex parts is involved.
B. Steel rivets
The kinds of steel containing a low amount of carbon are usually used because the low carbon makes them easy to fit effectively and settle. The low carbon also makes the rivets more flexible hence they can adjust easily unlike steel with a high composition of carbon.
C. Stainless steel rivets
This material is normally used to manufacture rivets because of the hardness and strength that it possesses. The rivets made from stainless steel are usually the ones used in the manufacture of aircrafts, automotives and in industries that produce power. They are also preferred due to their high level of corrosion resistance. This helps the stainless steel rivets last longer.
D. Copper rivets
This material is well known for its high heat and electricity conductivity, which makes rivets made from copper to be best suited for use in the manufacture of electrical and water devices. Copper is also flexible which makes it easy for it to be used in various applications.
E. Brass rivets
This is a tough material which contains low friction and it’s flexible enough for it to suit a number of roles. It also does not rust easily and therefore, because of this and other characteristics, it does not produce sparks. This property makes it suitable for brass rivets to be used in the manufacturing of gas devices.
IV. Rivet Selection Criteria
There are a number of properties to consider when it comes to the selection of the kind of rivet to use. These properties include:
-The range of grip. This refers to the range in which the rivet fits properly in the holes made in the two materials that it is supposed to connect. The range is usually the minimum and maximum diameter that has to be maintained for them to fit into each other perfectly.
-The size of the hole. When a hole is very small, the process of inserting the rivet is usually hard, especially in blind riveting. Also, when the hole is bigger in size than the rivet, the tensile strength decreases or even the materials lose their connection.
-Shear and tensile strength. Shear strength refers to the force that is to be applied on the rivet along the place where the joints meet while tensile strength refers to the force applied on the rivet through its length. The two have to be of the right measurement to ensure that the rivet fits properly.
-Joint thickness. It is crucial to determine the thickness of the parts to be joined to ensure that the manufacturer uses the rivet with the right “grip”. The range of grip should be dependent on the thickness of the two materials. If one uses the wrong measure of the length of the rivet, there might not be any room for the formation of the other side of the head which is responsible for holding materials together.
-Nature of the materials used. Different materials have different properties which help them suit different conditions. In instances where rivets of high strength are required, there are specific materials to be used. To avoid corrosion, the manufacturer should use stainless steel due to its ability to resist corrosion. Also, the rivets should possess similar properties, both physical and mechanical, as the parts being connected for them to join perfectly and to avoid reactions that might lead to corrosion.
-The style of the head. It is important to have the right size and shape of the secondary head formed so as to ensure that the rivet stays in place. In cases involving flush surfaces a countersunk head is usually preferred but a domed head is the one used in most applications. When rigid and soft materials are being joined together, it is normally advisable to use a large flange head.
V. Riveting Tools and Equipment
Rivet tools which can also be referred to as rivet guns are normally used to install rivets. The rivet tools come in various types as stated below.
Hand rivet gun – This is a simple kind of gun that uses a simple lever and involves squeezing so as to carry out its role. It is usually used to install blind rivets.
Heavy-duty lever riveter – These are an improved version of rivet guns which deal with a larger variety of rivets and are also easier to use. It normally has a bottle in the middle which is responsible for holding the mandrels that are snapped out after the installation process is over. Although it is manually done, it is faster than the hand rivet gun because of its improved lever action.
Cordless battery riveting tool – This type of rivet gun uses batteries to get powered making the installation process faster instead of using manpower. The gun also helps to collect the mandrels for the installer making the process faster.
Pneumatic rivet gun – These, on the other hand, use air that has been compressed to power them which makes it quick and easy to use during the installation of rivets. They are considered the quickest way of installation despite the fact they need to stay connected to a source of compressed air which makes them less portable.
Hydraulic riveter – This is usually powered by hydraulic forces to be fit for its role.
VI. Riveting Techniques
The riveting process starts by first preparing and clamping together the materials that are to be joined together. The two materials are then drilled to form holes where the rivet is to be inserted later. The holes have to be of the right measurement to ensure the perfect fitting of the rivet and for the two plates to be connected well. Then, a countersinking cutter is used to debar the holes for the rivets. Once they are of the right size and shape, the river is then inserted into them with the head underneath. A hammer is used on the rivet making the materials squeeze on each other and as the hammer continues to hit the rivet it fits completely into the hole. Continued blows by the hammer lead to the formation of the head which holds the materials firmly together. Once this is finalized, the formed part is assessed to see if any corrections have to be made or not.
VII. Common Riveting Issues and Solutions
The riveting process, just like any other process, has complications that might happen. These issues may include the following:-
- Loose rivets might result from the holes drilled being larger than the size recommended or the rivet being of a smaller thickness. It is, therefore, necessary to be cautious of the measurements to use. Bobbing and Frenching are some methods that can be used to tighten rivets.
- Rivet head deformation. This is because the secondary head does not have the right form in terms of its shape. The use of a dolly helps to keep the head of a rivet in place and to avert any kind of deformation on it.
- Cracked or damaged materials may be caused by the use of wrong heat treatment methods, which may result in going beyond the required tensile stress. Cracks may also be as a result of using materials that do not have the same structural properties.
- ·Corrosion is usually another complication that might destroy a given material or rivet. Protection from corrosion is crucial when using rivets to connect two materials. It occurs when metal reacts with oxygen and may be prevented using nickel plating, copper plating, or zinc plating, which should not be exposed to temperatures exceeding 2500C. Also, to avoid galvanic corrosion, metals with similar electronic capability or in a similar galvanic series should be used.
In conclusion, the selection of the right rivets and installing them in the right way are very crucial in the production of various parts. Rivets can be used instead of bolts or screws or nuts to join various parts of a device. Rivets come in different sizes and shapes to fit different roles in the manufacturing industry today. CNC machining which is a process used in rapid prototyping also uses rivets in the joining of various parts in the manufacturing process. Mold manufacturing also is part of CNC machining whereby mold designs help in the creation of various parts.