20 Different Types of Bolts and Their Uses

Bolts are a type of fastener. Fasteners are used to secure or fasten materials together. There are many types of nuts and bolts. Most, if not all, screw types have machine threads. A threaded bolt threads into nuts to hold or fasten materials together. Bolt types include eye bolts, wheel bolts, and machine bolts. This guide will tell you about the different types of bolts.

Types of bolts

These are different types of bolts:

Below are summaries of each of these common types of fasteners and a description of their important characteristics and uses.

Related posts: Different types of Nut and Bolts

1. Anchor bolt

Anchor bolts are used to connect structural and non-structural elements to concrete. The connection can be made using a variety of different components: anchor bolts, steel plates, or stiffeners. Anchor bolts transmit different types of loads: tensile forces and shear forces.

A connection between structural elements can be represented by steel columns that are attached to a reinforced concrete foundation. A common case of a non-load-bearing element attached to a structure is the connection between a facade system and a reinforced concrete wall.

2. Arbor Bolts

Arbor bolts are specifically designed for use with power tools, typically miter saws. These bolts hold the tool securely and keep the blade in place. The arbor is the shaft that holds the blade. On all American stationary saws that use a 10 “blade, the arbor is 5/8” in diameter where the blade is attached.

Arbor bolts differ from other bolts in that they are delivered pre-assembled. All arbor bolts have a washer that is permanently attached to the tip of the bolts. The enclosed washer gives the Arbor bolts a very distinctive appearance right from the start. These bolts also have a head with a sunken design that creates a noticeable ridge around the head of the bolt.

Typically, arbor bolts are made with a dark or black finish. They are also made with reverse threads. When you look at the shaft of an arbor bolt, it looks like it is backward as it has an inverted tread pattern like other types of bolts. This reverse thread is essential and is part of the main function of the arbor bolt.

3. Blind bolts

A blind bolt is a structural fastener that provides more strength and conformability than a typical rivet or weld. They were designed to forge a strong connection where traditional rivets or hex bolts were difficult to assemble or just couldn’t do the job.

On many occasions, restricted access means that using rivets or hex bolts is out of the question, and blind bolts were developed to deal with that exact problem. The effectiveness of the blind bolt solution means that, for decades, they’ve been the first choice for restricted access work in sectors like manufacturing, construction, and repair work.

4. Carriage bolt

A carriage bolt is a form of Bolt that is used to fasten metal to metal, or more commonly wood to metal. Also known as a washer head screw in Australia and New Zealand.

It differs from other bolts by its flat mushroom head and the fact that the cross-section of the shank, although circular for most of its length (as with other types of studs), is square just below the head.

This makes the bolt self-locking when inserted through a square hole in a metal band. This allows the fastener to be mounted from one side with just one tool, a wrench or wrench. The head of a carriage bolt is usually a flat dome. The shaft has no threads, and its diameter corresponds to the side of the square cross-section.

The carriage bolt was designed to be used through an iron reinforcement plate on either side of a wooden beam, with the square portion of the bolt fitting into a square hole in the ironwork. It is common to use a carriage bolt on bare wood, with the square section providing enough grip to prevent rotation.

The lock bolt is often used in security fastenings such as locks and hinges where the bolt only needs to be removable from one side. The smooth, domed head and the square nut underneath prevent the carriage bolt from being unlocked from the unsafe side.

5. Elevator bolts

Elevator bolts are threaded fasteners with a thin body and round head. These bolts can have either a square or ribbed neck to prevent the bolts from turning when a nut is tightened. They are used in tight spaces with moving parts such as in elevators and conveyor belts. With a thin head, they fit flush to the mating surface and don’t interfere in small or confined operational systems.

6. Eyebolt

An eyebolt is a mechanical fastener with a threaded shaft and a head forming a ring. Eyebolts are used to attach an eye to a structure, through which rope, cable, or shackles can be secured. A common use is to create a lifting eye so that a crane can be attached to machinery, with special-purpose lifting eyes rated for their safe working load.

Low-strength eyebolts are often formed from a length of the bar with the diameter of the nominal thread size. The head is simply bent into a ring from an unthreaded section of the bar. These types of eyebolts can carry axial loads reasonably well but should not be used for off-axis loads.

The opening where the end of the bar is closed to complete the ring may be welded but is likely to remain a possible point of failure.

7. Flange Bolts

Flange bolts have a circular flange under the head that acts like a washer to distribute the load. Flange bolts that are non-serrated are sometimes called frame bolts.

Used in automotive applications, plumbing, and more, flange bolts feature a washer-like flange beneath the bolt head that speeds production time and distributes the clamping load, offering protection to the mating surface.

To ensure a reliable, long-lasting connection between two sections of a large and enclosed area you will need to use a flange bolt. The best example, in this case, is the connection between the transmission and the engine in a vehicle.

8. Hex bolt

Hex cap screws and hex bolts feature a hexagonal head that is used when tightening the fastener. A hex bolt uses a washer under the head and a beveled end, while the hex bolts lack these features and require a nut.

These fasteners are widely used in construction, machine parts, and maintenance repairs. Hex cap screws and hex bolts are manufactured in a variety of sizes, finishes, qualities, and materials depending on the application.

9. J-Bolts

A J bolt is a J-shaped bolt that can be used in a variety of applications. They do not have a bolt head, but they can accept a nut at their threaded end. They are commonly used in the construction industry. Their bent end can be cast in a concrete slab as an anchor bolt. They are used in securing walls for concrete and roofing applications.

Many hardware and building suppliers stock J bolts, and it is also possible to order custom sizes directly from manufacturers of bolts and fastening products.

These bolts can be made from several different metals, and subjected to various treatments, depending on how and where they will be utilized. It can be handy to keep a few around the house for various projects, in the case of people who do a lot of do-it-yourself work.

10. Lag Bolts

Lag bolts or lag screws are technically screwed fasteners because they do not accept a nut. These extremely sturdy fasteners are usually used to connect heavy lumber or other heavy materials that are bearing an intense load.

These bolts differ from normal wood, self-drilling, or sheet metal bolts. Compared to most ordinary bolts, lag bolts are massive in size. Most lag bolts are at least one inch long and ¼-inch thick.

For example, wood screws are used when connecting an application with only wood materials. These wood screws boast coarse threading, but that threading does not encompass the length of the screw.

11. Machine bolt

Machine bolts are used to join two pieces of material together and are similar to hex bolts, except that they do not have a chamfered point or washer-support surface on the underside of the head. They are usually available with both a hexagonal and a square head.

Another fastener, machine screws, is often used interchangeably with machine bolts, which creates confusion. Machine screws are typically smaller than machine bolts, but they are usually evenly threaded along the length of the fastener.

Unlike other types of screws such as wood screws or sheet metal screws, the fasteners have a flat tip rather than a pointed or conical tip, as is common with these other types of screws. Screws are generally designed to either be used with pre-drilled holes or to be driven into materials where the screw creates its own thread in the material when tightened.

In contrast, bolts are designed to be tightened by applying and torquing a mating nut to the end of the bolt. While nuts and bolts are paired fasteners, nuts are typically not used with bolts that are instead screwed into pre-drilled holes.

Both machine bolts and machine screws come in a variety of head styles, including hex head, which is often combined with hex nuts, as well as flathead, oval head, and cheese head, to name a few.

12. Hanger Bolts

A hanger bolt is a double-ended bolt that is typically used to attach legs to furniture. Hanger bolts are very much unsung heroes of hardware. These bolts aren’t fancy, they aren’t pretty and you may never hear about them or think about them. They aren’t like those other bolts that are always showing off, but hanger bolts make your home what it is.

You see, hanger bolts are used to attach legs to furniture. So, once you really start looking around, you’ll realize that hanger bolts are all around you all of the time. If you’re going to put a piece of furniture together, then you’re going to need to know all about hanger bolts.

13. Plow Bolts

Plow bolts are typically used to attach the plow share (blade) to the frog (frame) and allow the earth to pass over their heads without obstruction to the moldboard. They are also used to fasten the blade of bulldozers and motor graders.

Plow bolts have a small, round countersunk head and a square neck – the width of the square (measured across the flats) is the same size as the nominal diameter of the bolt. The top of the head can be flat (for plows) or dome (convex) shaped (for dozers/graders). The conical (tapered) bearing surface of a plow bolt is 80°.

14. Rock Bolts

A rock bolt is a long anchor bolt, for stabilizing rock excavations, which may be used in tunnels or rock cuts. It transfers load from the unstable exterior to the confined (and much stronger) interior of the rock mass.

Rock bolts are almost always installed in a pattern, the design of which depends on the rock quality designation and the type of excavation. Rock bolts are an essential component of the New Austrian Tunneling method.

As with anchor bolts, there are many proprietary rock bolt designs, with either a mechanical or epoxy means of establishing the setting. There are also fiberglass bolts that can be cut through again by subsequent excavation. Many papers have been written on methods of rock bolt design.

15. Sex Bolts or Chicago Bolts

Sex bolts are fasteners with a barrel-shaped female component with internal threads covering the threaded male component. The female component serves as the nut and is almost the same length as the male component.

Both components have a flange that serves as the bearing surface and makes the connection surface more even. These bolts are ideal for fastening materials sensitive to abrasive parts. They are used in paper binding, helmets, railing systems, furniture, playground equipment, signages, bathroom partitions, and other products.

16. Shoulder Bolts

A shoulder screw, also known as a shoulder bolt, has a shank with a larger diameter immediately below the head, which “steps down” down to a smaller diameter for the length of the thread.

The change in diameter creates a “shoulder” that can be tightened firmly against the screwed-on part. This allows a shoulder screw to be firmly attached to one part without clamping the other, creating axial clearance.

The shaft provides a smooth bearing surface for a bolt connection between the parts. A shoulder screw can be used in conjunction with a sliding bearing such as a nylon bushing to allow improved rotation between the parts.

17. Socket Head Bolts

Socket cap screws are machine screws with a cylindrical barrel-shaped head containing a hexagonal socket. The head has a smaller diameter than most other machine screw heads, typically just 1.5 times the nominal thread diameter. Socket cap screws may also be referred to as socket head cap screws, cap head socket screws,s or hex socket head screws.

Fastening for these components requires no external clearance, which is typical of screws such as a hex head for it to accept a spanner or socket. These properties mean that socket head cap screws are well suited for use within confined spaces.

18. Square Bolts

Square head machine bolts were the industry standard prior to hex bolts gaining prominence. Square bolts are now most commonly used for aesthetic purposes to provide a rustic look in a new structure or to match existing fasteners in an older structure. Square lag screws are also used for these purposes.

19. T-Head Bolts

T-Head bolts are mainly used with a nut to join an object with a T-shaped slot so that the head of the bolt sits flush or below the material surrounding it. T-head bolts are commonly used in a number of applications, including machine tool clamping fixtures and pipe clamps. The T head configuration enables the head to be placed into a slot and held in place with a 90-degree turn of the head.

20. U-Bolts

A U-bolt is a bolt in the shape of the letter U with screw threads on both ends.

U-bolts have primarily been used to support pipework, pipes through which fluids and gasses pass. As such, U-bolts were measured using pipe-work engineering speak. A U-bolt would be described by the size of the pipe it was supporting. U-bolts are also used to hold ropes together.

For example, a 40 Nominal Bore U-bolt would be asked for by pipe work engineers, and only they would know what that meant. In reality, the 40 nominals bore part bears little resemblance to the size and dimensions of the U-bolt.

The nominal bore of a pipe is actually a measurement of the inside diameter of the pipe. Engineers are interested in this because they design a pipe by the amount of fluid/gas it can transport.

As U-bolts are now being used by a much wider audience to clamp any kind of tubing/round bar, then a more convenient measurement system needs to be used.

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