Mechanical fasteners are hardware devices used for adjoining materials together. They are used in millions of assemblies around the world and are available in a range of sizes to fit different type of applications. Common fastener types are available in different forms.
They can be broadly classified into non-permanent fasteners and permanent fasteners. Non-permanent fasteners can be further divided into sub categories of general fasteners and threaded fasteners.
General fasteners are often affiliated with shafts and commonly consists of pins, keys and retaining rings among others. The most commonly used threaded fasteners are bolts, screws, concrete anchors and nuts.
Washers are used with threaded fasteners and they are made up of a thin plate with a hole in the middle. Their fundamental role is to help distribute the load of a threaded fastener. Additionally, rivets work as permanent fasteners and are destroyed upon disassembling.
Common fastener types are available in different forms.
Bolts
The most common type of bolts includes carriage bolts, hex head bolts, machine screws, shoulder bolts and socket cap screws among others.
Carriage bolts are designed with a countersunk head. The bolt has a square section underneath the head which prevents further tightening of the bolt once the nut is fixed in place.
Hex head bolts are designed with a hexagonal head and a threaded straight shaft. The most common examples of such bolts include hex cap screws, trim head hex cap screws and hex tap bolts.
Machine screws are designed with a flat head at the tip and a shaft entailing the head, which is threaded. These screws are fit for a wide range of applications and are therefore available in variable drive types and heads.
Shoulder bolts are essentially machine screws with a shoulder in the straight shaft between the head and the threaded part.
Socket cap screws are typically used with a socket wrench. They indicate a kind of fastener with ratio of 1.5 of head diameter to screw shank diameter.
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| Carriage bolts | Hex head bolts | Machine bolts | Shoulder bolts | Socket cap screws |
Screws
Some of the most commonly used screws include hex lag screws, wood screws and sheet metal screws, among others.
Hex lag screws are commonly used with a wrench, for machinery required to wood floors and heavy duty practices.
Wood screws are made up of a smooth shank head entailed by coarse spiralling threads following the straight shaft into a tapered pointy end. They are commonly installed in drilled holes to slide through pieces of wood and join them, without causing the wood to split.
Sheet metal screws (SMS) have spiralling threads along a straight shaft with a tapered end. The tapered end enables SMS to perforate sheet metal without drilling a hole first. These SMS can also be used on plastic as well.
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| Hex lag screws | Wood screws | Sheet Metal Screws |
Concrete Anchors
Using fasteners for applications concerning concrete is very different from using fasteners for general applications such as adjoining pieces of metal in place. Fastening to concrete requires the use of concrete anchors, whose installation and use is much more strenuous than other fasteners. This is due to the complexity required in order to fasten something to a solid base material such as concrete.
Concrete remains the most widely used and available base material in the world and therefore the use of concrete anchors is vital in order to hold structures from this base material in place. Some of the most common concrete anchors used include drop in anchors, sleeve anchors, and wedge anchors.
Drop in anchors have internal threads and their main use lies in the creation of handrails and lighting fixtures among several other fixtures.
Sleeve anchors are made of a threaded stud with a blunt cone head on the top and a nut and washer on the other side. These anchors are especially suited for hollow concrete applications.
Wedge anchors are used to attach and hold materials in place with solid concrete surfaces. It consists of a blunt head on one end with a threaded straight shaft entailing the head and a nut and washer on the other side.
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| Drop-in anchors | Sleeve anchors | Wedge anchor |
Nuts
Nuts are used in conjunction with bolts. The most common types of nuts include cap nuts, castle nuts, hex finish nuts, square nuts, T-nuts and structural heavy hex nuts, among others.
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| Cap nuts | Hex finish nuts | Square nuts |
Washers
Washers are used along with threaded fasteners and the common types include backup rivet washers, dock washers, fender washers, flat washers, lock washers, structural washers and square washers, among others. (Albany County Fasteners, 2018)
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| Backup rivet washers | Dock washer | Flat washer |
Rivets
A permanent type of fastener commonly used is rivets. Unlike bolts and screws, rivets are non-removable. They fundamentally function to hold plates or sheet metal in place.
Rivets are used in applications such as civil structures made of steel, aircraft components, automobiles, clothing, ships, etc. Different rivets are used for different purposes, varying with their application. Therefore, there are various types of rivets but the two most commonly used ones are solid rivets and pop rivets.
Solid rivets are known to be one of the earliest rivets in use and are highly reliable. They are made of a cylindrical shank head followed by a straight shaft. These kind of rivets are best suited for civil structures, for example bridges.
Pop rivets are the most popular for general use. This is because of ease of installation of the pop rivets. Pop rivets are tubular in shape and are used to effectively connect two pieces of material in a quick and simple manner. However, pop rivets are not as reliable as solid rivets as they cannot withstand large loads. (Kau.edu.sa, 2018)
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| Solid rivets | Pop rivets |
Everyday Common Fastener Types
Millions of fasteners are being used every day to construct the things we see around us. Different common fastener types aid in different applications and are made to facilitate the functionality of a given mechanism. Some of the most commonly and frequently used fasteners have been mentioned in this article but there are numerous more that help in various operations and make a considerable number of duties feasible every day.
References
- Kau.edu.sa. (2018). [online] Available at: http://www.kau.edu.sa/GetFile.aspx?id=244374&fn=Mechanical%20Fasteners.pdf [Accessed 19 Jan. 2018].
- Albany County Fasteners. (2018). Types of Fasteners | Nuts, Bolts, Washers. [online] Available at: https://www.albanycountyfasteners.com/Fastener-Varieties-s/1130.htm [Accessed 19 Jan. 2018].