THE 36 MAIN TYPES OF SCREWS AND THEIR USES - TECHNOLOGY - 2025

The types of screws can be classified according to the head, material, function and utility, having in total more than 36 classes. Screws are fasteners used to join two or more pieces temporarily or permanently. These are extremely important elements in structures, as it is a safe and removable joint system.

Screws consist of two basic parts which are the head and the shank. And on the stem are two more distinctive elements. A smooth part, which is called the neck, and a final section known as the thread.

The head is the part of the screw that allows the existence of various types of parts. This is because the shape of the screw head is what determines the tool that must be used to tighten the piece. There are several types of screws, and these can be divided according to their head, material, finish, utility, and function.

According to his head

Hex head

Source: Ralf Roletschek

This is one of the most widely used screws. As its name implies, it has a hexagon-shaped head and is often used for fixing or mounting parts and even for pressing.

Hex head with pivot

Source: Source: © 2010 by Tomasz Sienicki

This screw, in addition to allowing highly tightened joints, offers the possibility of immobilizing the joint using a pin in the pivot.

Hexagon head with flange

Source: Afrank99

This type of screw also allows a high torque to be applied. But its advantage is that it is not necessary to use a washer between your head and the part to be joined.

Pointed End Hex Head (Set Screw)

Source: Frank C. Müller

It is a rod that is threaded at one or two of its ends. It is known as a set screw, because it prevents movement between the joined parts, since it is placed between the nut and the screw. It is used for assembly.

Cruciform slotted and slotted head (phillips)

Source: Uwe Hermann

These screws are used when no great torque is needed. They have a straight groove on the surface of their head that is cut perpendicularly.

In this case, flat head screwdrivers are needed. Both allow to hide the head of the screw as long as a countersink is made to the entry hole of the piece.

Square head

Source: Tosaka

Like hex head bolts, this type of bolt is also used in cases where high torque is required, such as fixing cutting tools.

Cylindrical head with internal hexagon

Source: Julo

Also called Allen, these screws have a hexagonal hole in the head to fit an Allen key. They are cylindrical pieces that are used in joints where high tightening is needed and which are also narrow.

Butterfly

Source: Rolf Dietrich Brecher from Germany

This type of bolt is used for joints that do not need a great tightening. In addition, they are often subjected to frequent manual assembly and disassembly.

Round head

Source: Ssawka at Polish Wikipedia

This type of screw has a spherical shaped head and a flat base.

Sebum drop head

Source: Ssawka at Polish Wikipedia

This is a screw that has a conical shaped bearing surface with a slightly oval head.

Torx head

Source: Hmms at the English Wikipedia

It is a screw with a hole in the head that is shaped like a star.

According to your material

Of aluminum

Source: Ssawka at Polish Wikipedia

They are one of the most common screws. The advantage of these is that they are lighter than steel ones. This quality makes aluminum screws ideal for working with plastic or wooden surfaces.

Duralumin

Source: Ssawka at Polish Wikipedia

This is a variety of the aluminum screws. In addition to being made with this component, they are also combined with other metals such as chromium, which increases their durability.

Stainless steel

Source: Renato.pierri

These types of screws are ideal for outdoor projects. In this case, parts are needed that are capable of withstanding any environmental condition. And stainless steel can withstand very humid conditions without deteriorating because they do not rust.

Of plastic

Source: Emilian Robert Vicol from Com. Balanesti, Romania

Plastic screws are ideal for those who need screwdriving parts that can withstand different external conditions such as humidity and liquids. These types of screws are special for plumbing, for example.

Brass

Source: Hi-Res Images of Chemical Elements

The screws of this material are specially designed for jobs that involve wood. And, in addition to being very resistant, they are aesthetically more appropriate than any other screw thanks to the fact that they offer decorative touches.

According to its finish

Expired

Source:

These screws have a silver appearance. When cadmium oxidizes, it does not generate bulky corrosion products like zinc. And this helps them to be used in close tolerance functions.

Galvanized

Source:

It is a screw with a finish that is a metallic zinc deposit. It has a semi-gloss appearance and is often used to protect steel from corrosion.

Its use is recommended for industrial environments, since if it is used in humid environments a white corrosion powder is created that can interfere with movement.

Tropicalized

Source: Ssawka at Polish Wikipedia

The appearance of this screw is iridescent yellow. This finish is achieved by applying zinc (galvanized) and a later chrome plating. In this way, the resistance of the part against corrosion is increased.

Nickel plated

Source: en: User: Cburnett

It has a shiny metallic finish and its function is to protect the base metal of the screw. This finish also increases the brightness of the piece. This type of screw is often used to give decorative finishes.

Brass plated

Source: User: Saforrest

This type of screw is also used for decorative purposes thanks to its shiny metallic appearance. The objective of this finish, as in the other cases, is to protect the parts from corrosion.

Phosphatized

Source:

It is a protective layer that consists of immersing the screws in a solution containing phosphoric acid. They are grayish black in color.

Bluing

Source: Hmms at the English Wikipedia

These screws are semi glossy and have a deep black color. They are like this because they are subjected to a controlled oxidation of the steel, which is what produces this black layer that makes them resistant to corrosion.

According to its function

Self Tapping and Self Drilling Screws for Sheet Metal and Hardwoods

Source; Maksym Kozlenko

What characterizes self-tapping and self-drilling screws is that both pieces are capable of cutting their own path.

The self-tapping, have an end that has a conical shape. They can be flat, rounded, oval, or flat-headed. In this type of screw, the thread is thin and has a flat bottom so that the plate can be lodged in it.

They allow joining metal to metal, metal to wood, metal to plastic, among others. The edges of these pieces are sharper than that of wood screws.

As for self-drilling screws, they have one point that is a drill bit. This means that with them it is not necessary to drill guide holes to use them. They are usually used with heavier metals.

Threaded Wood Screws

Source: Haragayato

Also called lag screw for wood, they have a thread that occupies 3/4 of the shank. They are characterized because they taper at the tip to open the way as they are inserted, this to facilitate self-tapping.

To use this type of screw it is not necessary to make a previous hole. They are usually screwed in with a screwdriver, either manual or electric. In this case, the type of head may vary.

• Flat - Used when the screw head needs to be submerged or flush with the surface.
• Round: it is used to join pieces that due to their thinness do not allow the screw to sink. But it is also used to fix parts that need washers. It is a type of screw that is easy to remove.
• Oval: used to join metal elements. And thanks to the shape of the head, it allows it to sink into the surface and only the upper part, which is rounded, remains protruding. They are also easy to remove and aesthetically look better than flatheads.

Tapping screws for metal connections

Source: © 2010 by Tomasz Sienicki

It is a type of screw that is used to fix metal parts. They have a triangular thread and can be screwed onto a washer nut in a through hole or knockout hole.

These screws are often used to fix parts of different machinery. In these cases, parts are needed that are strong enough to withstand the stress to which the machine is subjected. These must be fully tightened so that they do not loosen during operation.

Lag Screws for Walls and Wood

Source: Rfc1394, Waterced

These types of screws are thicker than classic wood screws. These lag screws are often used to screw supports for heavy elements, especially those used to hang things on the walls of buildings such as air conditioners, among others.

To use this type of screw, the wall must be drilled depending on the diameter of the screw that has been chosen. Subsequently, a plastic plug is inserted and the piece is screwed.

According to its usefulness

Union screw

Source: Dmitry G

It is a type of screw that is used to join two pieces. This connection is made through a through hole that does not have a thread, while it is threaded into the other, as if it were a nut.

Through screw

Source: Hermann A. Wiese

It is a screw that is used to pass through the pieces to be joined. It does not screw into any of them. They are often used for castings or light alloys.

Asparagus

Source: Suyash Dwivedi

This screw is a rod threaded at both ends that does not vary in diameter. In this case, the parts are threaded. One is the one in charge of threading, while the other part has an external thread. Fastening is done with the use of a nut.

Tamperproof screws

Source: Author / auteur: JoKoT3 (Jonathan Gibert)

This is a type of security screw that once it has been screwed in, it is impossible to remove. The only way to do this is by forcing the piece until it breaks. This is achieved thanks to the fact that it has a design with a tilted head inside.

Which means that when trying to loosen it, the key will come out but without being able to remove the screw. Due to their functionality, they are used in jobs located in public places where many people have access.

Precision screws

Source:

This type of screw is characterized by having a great resistance to traction and fatigue. They are usually used when it comes to machines that are constantly exposed to pressures, speeds and efforts, since these processes need stronger joints so that failures do not occur.

Miniature screws

Source: Mijnnaam (Nico.rikken (talk) 12:31, 6 November 2014 (UTC))

Today electronic components tend to get smaller and smaller. Therefore, it has become necessary to create practically minute screws.

These pieces are characterized by being of the self-tapping type and being made of soft materials such as plastics. In addition, its head must be adapted so that it can be used with small, precision screwdrivers.

Ordinary screws

Source: Brianiac

These are screws whose hole diameter is usually 1 millimeter larger (approximately) than that of the shank of the piece. When making joints with this type of screws, it is required to have a smaller adjustment between the diameter of the piece and that of the drill to be used.

Calibrated screws

Source: Haragayato

Calibrated screws differ from ordinary screws due to their geometric characteristics. As stated, in ordinary screws the diameter of the hole must be 1 millimeter larger than that of the shank.

But in the case of calibrated ones, both diameters are almost the same size. Therefore, they are often used for precision joints and for the formation of rigid knots.

High strength bolts

Source: Publicstock

What differentiates high-strength screws from others is that the characteristics of the steel used for their manufacture must be standardized. That is why the manufacturers of these screws must, by obligation, deliver a warranty certificate.

This type of piece must carry both the letters TR and the designation of the type of steel and the manufacturer's registered trademark on the head.

References

1. Zavala, G. (1985). Theme: of screws. Autonomous University of Nuevo León. Mexico. Web: eprints.uanl.mx.
2. Ramirez, W. (2013). Screws and bolts. Alas Peruanas University. Peru. Web: documents.mx.
3. Valdez, C. (2015). Types of screws and their functions. Web: prezi.com.