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Fasteners 101: Types of Fasteners and How to Choose Them

Fasteners are highly useful in making different types of objects and ensuring that they function optimally without falling apart. While the first fastener was made using wood and was used in agriculture, today, many materials are used to prepare these. There are even more types of fasteners, each designed and constructed to play a key role in a specific industry. This article will shed light on these fasteners and how to select the right one. 

What is a fastener?

Assortment of sturdy steel hex head bolts and nuts on a dark surface, highlighting industrial strength and reliability

Fasteners have been around since 4000 BC. They can be defined as objects used to join two materials or surfaces temporarily or, in some cases, permanently. Basically, their main purpose is to create a joint that can be demolished without harming the two surfaces.

Fasteners or fastening are mostly prepared using metals such as aluminum and brass. Some non-metals apart from titanium are also used for construction applications. 

Types of Fasteners

Screws

These are a type of fasteners that are used for a variety of purposes. For instance, they can combine wooden boards but are equally capable of joining electrical parts. What makes them so useful is their availability in different forms, such as fine screws and coarse threads.

Based on their function, screws can be further divided into many different types, including:

  • Machine screws

Machines comprise several parts which need to be fastened together to make them function. For this, they require fasteners such as machine screws. These can be identified by their cylindrical head and a shank with fine, regular threads. 

Machine screws are one of the easiest-to-install fasteners. Mostly, there is a pre-drilled hole, and all you need to do is insert it either manually or using a screwdriver. 

A feature that is most interesting to this type of fastener is its versatility. You’ll see machine screws in various sizes, shapes, diameters, and lengths. One can pick and choose them as per the application.

A few types of machine screws are standard screws like pan heads, hex washer heads, captive screws, locking screws, vented screws, and thumb screws.

  • Tapping screws

The other names for this type of fastener are tapper screws, metal screws, and sheet metal screws. As the name suggests, these screws are extremely user-friendly. Just tap them, and they get inserted into places where drilling beforehand is not an alternative. That’s how it works well for metal sheets or some other surfaces. 

Talking about the physical structure of this type of fastener, it varies from pointed to blunt and even flat. Its ability to stay resilient in shaky environments with resilience and strength makes them an ideal candidate for use in the automobile and the construction industry. 

Self-tapping screws, drive screws, self-drilling screws, and thread-cutting screws are some of the most common kinds of tapping screws in the market. 

Nuts

Nuts as fasteners are often called the female partner of a joint. The male counterpart is a bolt (to be discussed later). 

Nuts have external threads and are hollow in the center. This place is sometimes filled with screws. With a head and a cylindrical body, they can be utilized to join two or sometimes more than two materials.

  • Hex nuts

These nuts derive their name from their six sides and can be assembled easily with the help of a wrench. Hex nuts are ideal fasteners when you have to join a wood to a metal. 

Size is no issue with hex nuts. You can buy as per your requirements.

  • Castle nuts

No fastening in the mechanical industry is complete without a castle nut. These nuts are different from regular nuts, with notches and slots to hold pins. Such designs suit applications that need strong connections between the joints in addition to a little torque.

Apart from this, they are single-use fasteners and can’t be loosened or used again due to their design. 

  • Weld nuts

The word weld says it all. This type of nut requires welding first to affix them to the surface. This works well for components that are hard to reach otherwise. 

Featuring an internal thread, they come in two varied shapes: rounded heads and slap-shaped. They are mostly used in applications that require supreme-quality nuts only.

Weld nuts are of various types: round base nuts, tab base nuts, slab base nuts, and tube end nuts. 

Bolts

Galvanized steel hex bolt and nut on a neutral background, highlighting the hardware's threaded detail for secure fastening

Now, let’s talk about the male partner of the nut-bolt association. Bolts are fasteners that are to be used with nuts for a strong and secure connection. They have an external male thread that will come together to join two separate parts only when the corresponding nut has the required female threads. 

Similar to nuts, bolts are of a few types, including:

  • Carriage bolts

Another name for these types of bolts is coach bolts or plow bolts. Though mostly used to fasten two wood pieces, they may also be applied to combine a wood piece with a metal piece or two metal pieces. 

Part of their popularity in the wood and furniture industry comes from their shape. Carriage bolts have a round, flat head, which makes them visually appealing. The fastening so produced is nearly permanent. 

  • Eye bolts

When a chain is required to be fixed to a surface, eye bolts come to the rescue. There is no head, just a ring meant for fastening. Eye bolts come with internal threads and a smooth shank. The latter redefines their strength, especially when attaching wood to metal and vice versa. 

Their ability to assemble and disassemble makes them ideal for using the second time, and not just once. 

Washers

Metal square washer with rounded corners and a central hole, isolated on a white background, used for load distribution

Washers are fasteners that keep your nuts, and axle bearings stay secure in one place. These are placed just beneath the other fasteners and prevent them from becoming loose and falling off. However, their use is not limited to this alone. 

These fastening agents may also be used to separate two parts and avert leakage. While this means these should be plane and horizontal, the shape may vary as per the requirement. In addition, they are available in different material types, namely, rubber, metal, plastic, and fiberglass. 

You can further select the type of washer on the basis of your primary requirement: prevent corrosion or deal with moisture. 

  • Flat washers

Their design is just apt for distributing the load of the other fasteners evenly. Hence they suit metal as well as wood materials. 

They have a unique ability to fasten screws of several types, such as machine screws, wood screws, and 

self-tapping screws. They are also a good match for fasteners that have threads such as nuts, bolts, and ones with holes. 

However, one must use a washer of the right size to ensure the longevity of the joint. 

  • Lock Washers

Nuts and bolts may loosen up over a period of time due to overload or vibration. Lock washers act as locking agents and prevent them from moving from their respective places. In the market, there are many lock washers each designed for a specific function.

  • Toothed washers: serrations of external teeth are present on their external surface. These are responsible for holding the fasteners in place in the electrical equipment and automotive industry.
  • Ribbed lock washers: their circumference features many ridges or projections. With the help of these, ribbed lock washers are able to grip the mating surface better.
  • Nord lock washers: each washer of this type has a wedge-shaped cam on a single side. As you fasten two washers together, they lock into each other, providing a firm grip. Perfect for the oil, gas, and construction industry. 
  • Wave washers: Like their name, these washers are wavy. On pressing, they act like a spring. When you do the same with the mating surface, pressure is produced, keeping the joint tight. Suspension systems and ball bearings use these more frequently.
  • Internal tab lock washers: the inner circle has a tab that is bent towards the inner side. These are designed to lock the keyway of a shaft.
  • External tab lock washer: the tab is on the outer circumference in this. With this, they are able to hold the surface tightly and thus qualify for high-performance applications such as aerospace.
  • Split lock washers: They come in a helix form, which produces tension between the fasteners and the surface. This ability is why they are used in many industries, such as general machinery and construction. 
  • Spring washers

Tension between the fasteners is one way of preventing nuts and bolts from moving apart. Spring washers with their conical design and split end can do that. This end enacts a spring motion between two surfaces. While this prevents unlatching, it also makes the joint more flexible. 

You can find them in the doors and windows of automobiles and your homes. The best part is that you can install them manually, depending on the application. Or use automated equipment for the same. Various shapes and sizes are available. 

Rivets

Two rivets with white plastic anchors, one with a flat head and the other with a hooked end, on a light background

From small electronic assemblies to large structures, rivets can provide permanent fastening to all. However, one downside is that once you install, there is no way to remove or reuse them. Nevertheless, you won’t even need to do that. 

Rivets resemble cylinders with heads at one end that taper down to the tail along a long shank. The shape of the head may vary from round to hexagonal. While all the other types of fasteners discussed here are good, nothing compares to the strength and reliability of rivets. 

They are even favored over single-use fasteners.

  • POP rivets

When two materials are to be fastened together permanently, POP rivets or blind rivets are used. They are tubular in form with a special head (either slotted or countersunk). There is also a central rod called a mandrel.

POP rivets can be further divided into:

  • Open-end Rivets:  Commonest of all, this one has an oval head. Internal threads are also present.
  • Countersunk rivets: Their flat head makes them an ideal fastener for sheet metal surfaces.
  • Closed-end rivets: When one side of the assembly is hard to reach, you need a flat head rivet like closed-end rivets. Its internal threads ensure durable fastening.

They are easy to install; all you need is a hammer or a pneumatic gun.

  • Solid rivets

These are simple fasteners with a strong body, a long shaft, and a head. Their anterior is often deformed due to the hammering done to fix them in place. Their robustness is why they are used in building aircraft.

  • Semi tubular rivets

They are either made up of metal or plastic and have a hole right at the top. It is visible just opposite the head. The head structures may vary and can be oval, flat, undercut, or countersunk. When you apply force to install it, the tubular part moves out. 

If you have less space but need a solid fastener, a tubular rivet can be used.

Nails

The last type of fastener on our list is the nails. These are one of the oldest types of fasteners and have been used in construction since the Bronze Age. They form the backbone of any construction and can be purchased in many shapes as well as sizes. 

Nails as fasteners are mostly used to combine wood articles but work well for concrete, drywall, and plastic. They are constructed in various materials such as copper, iron, bronze, and aluminum. Just like welds and rivets, nails are also counted as permanent fasteners. 

Nails are of various types:

  • Common types: Most popular of all, these feature a round head and are used to join timber.  
  • Box nails: Slightly thinner than the common nails, they are considered for lighter constructions.
  • Drywall nails: 1 inch to 1 1/2 inches long; drywall nails are for hanging purposes on drywalls.
  • Finishing nails: A look-alike of timber nails, these are known for providing a neat and clean finish.
  • Double-headed nails: With two heads, they can be removed easily. You can use them in construction scaffolding or temporary braces.
  • Masonry nails: Since they are meant for hard masonry surfaces, these nails are thicker and much stronger.
  • Roofing nails: these can be identified by their large heads. The latter design prevents the tearing of thin roof materials such as shingles or asphalt. They may be galvanized to prevent rusting.
  • Annular rings: They have rings all along the length of the shank. These nails are used to attach timber. 

How to choose a fastener

  • Size and shape: Think about the thickness of the material to be fastened. Also, check the size of the hole; it should be compatible with that of the hole.
  • Material: The environment matters a lot. So, if a nail is to be used in an aircraft, it should be able to handle the intensity of the vibrations.
  • Strength: A weak fastener may lead to equipment failure. Similarly, a robust one can hurt the function. So, remember the load the equipment can handle to make a selection.
  • Quantity: Before starting, calculate the number of fasteners you will require. This will prevent you from buying in bulk and wasting them.
  • Cost: the durability and purpose are two important objects when buying a fastener. So, do not fall for cheap marketing gimmicks. 

Conclusion

Fasteners are essential for almost all industries. Without them, it would be difficult for these sectors to operate. However, it is also important to know the type of fastener you need and to choose the correct one. We hope our article helps you make the right choice. And if you are looking for quality product assembly, get in touch with our HiTop Industrial team for consulation and service. 

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