What Is Bolt and Its Types?

A bolt is a mechanical fastener with threaded shafts. The bolts are closely related to screws, which are also mechanical fasteners with threaded shafts.

This type of fastener is usually inserted through two parts, which have aligned holes. By some definitions, whether a thing is a bolt or a screw depends on how it is used.

The bolt is inserted through the parts that all have unshielded holes, & a nut is then screwed onto the bolt to provide a clamping force & prevent axial motion.

A screw my first pass through the first part with an evacuation hole, but its threads are being fastened with threads in one part. Using two numbers separated by a point, the bolts are classified according to their strength.

This grade is often stamped on the heads. The points are not decimal but act as a denominator. The first number is the ultimate tensile strengths (UTS) in MPA divided by 100, & the second numbers are the ratio of yield strength to UTS.

Common classes are 5.8, 8.8, & 10.9. For example, grades 8.8 bolt has a UTS, at which it fails, is 800 MPa and will receive 80% (640 MPa) of this value.

A bolt is a type of fastener that is used to connect two parts together. The bolts join the part non-permanently, i.e., the parts can be separated from each other using a suitable tool. Nuts are also used on the bolt to make the fastening process more effective.

Parts of a Bolt:

#1. Head

The head is the topmost part of a bolt. It serves as a gripping surface for the instrument. To tighten or loosen the bolt, a tool with the appropriate bit must hold the head. Most bolts have a head wrench-type.

In other words, a wrenching bit should be placed around the head of the bolt. However, some bolts use screw-type heads where the bit is placed in the center of the head. Whether wrench or screw-type, all bolt heads provide a gripping surface so that the bolt can be tightened or loosened with a tool.

#2. Shank

There is a conch under the head. The Shank is the smooths part of a bolt that is devoid of threading. It is designed to prevent radial movements of the included workpiece.

Without the leg, the bolt is more likely to be loose. Some workpieces produce vibrations, while others are exposed to vibrations in the environment around them.

When the included workpiece vibrates, the bolt may loosen if it does not feature a leg. Lack of leg means that the bolt will fully extend from top to bottom (with the exception of the head). Therefore, the vibration may push the bolt backward from the included workpiece.

#3. Threading

All bolts have threading. Threading is one that allows a bolt to move in or out of the workpiece. However, most bolts do not have complete threading.

They have ahead, followed by a smooth leg and finally threading. Depending on the type of bolts, the Shank may cover a larger surface area than threading. However, all bolts have threading.

The threading of a bolt works together with the internal threading of the workpiece to join them. The bolts have external threading that is located outside their bottommost part. This allows the external threading bolt to be moved in or out of the internal threading of the workpiece.

Types of Bolts:

The Bolts are one of the most versatile structural fasteners, available in a vast array of configurations to suit different materials & strength requirements.

These fasteners differ mainly in thread specification, length, and head size, with different combinations of these characteristics resulting in bolts with different functions.

They usually require a drilled hole and a filler nut or mating portions taped for installation, and, unlike screws, they are generally not tapped.

The terminology that distinguishes between bolt types is often for inconsistent and incorrectly used screws, so it is best to select your bolt based on your project specifications rather than the exact name indicated on the supplier’s website.

1. Carriage Bolt:- Carriage bolts feature a domed or countersunk head with a square underside that prevents post-installation from operating. They are often used with wood & masonry.
2. Flange Bolt:- The flange bolt is a special type of hex head bolt that has an integrated flange that acts as a washer component to distribute the load more evenly.
3. Hull Bolts:- Similar to carriage bolts, some hull bolts have a square-shaped counters top. Others have a domed design. These bolts are ideal for heavy-duty applications such as industrial machinery.
4. Hex Head Bolt / Hex Head Cap Screw:- Characterized by their hexagonal head shape, hex head bolts are a wide range of bolts requiring installation with a wrench. They are available in many lengths & threading varieties. The hex head cap screw has a tight tolerance and is the most common hex bolt range.
5. Square Head Bolts:- Like hex head bolts, square head bolts are defined by their head shape — that is, square. This head design facilitates tooling gripping while allowing easy installation.
6. Socket Head Cap Screw / Allen Bolt:- The socket head cap screw has a flat chamfered top surface with smooth or curly cylindrical sides. Forged heat-treated alloy examples are high-strength fasteners intended for the most demanding mechanical applications with special alloy aggregates.
7. Additional bolt types:- Other bolt types that we can custom manufacture include anchors, belts (e.g., eye, hook, J, & U), countersunk, lag, & T-handle bolts.

Types of Nuts:

The Nuts are available in a variety of shapes, sizes, materials, & thread patterns. Although your nut selection is somewhat constrained by your choice of the bolt – especially in terms of size and threading – you should still choose the size and material of the nut head that best suits your application.

1. Coupling Nut:- A coupling nut is a long, cylindrical nut that connects two male threads. These components can be used to add length to an installation.
2. Flange Nuts:- Similarly to flange bolts, the flange nuts are around the flange that acts as an external washer and allows for greater load distribution.
3. Hex Nuts:- Hex nuts are hexagon-shaped. This nut is extremely versatile but requires a wrench for installations. The types of hexes nut we supply include finished hex, semi-finished hex, hex flange, hex jam, hex, and slated hex.
4. Locknuts:- Locknuts are available in a range of sizes and are used to secure other nuts and prevent them from loosening. Types of locknuts include all-metal locknuts with top or side locking features, serrated hex flange, and nylon inserts.
5. Slated Nuts:- Slated nuts are designed and manufactured such that they can form a locking mechanism with a cotters pin or a safety wire.
6. Square nuts:- Square nuts are characterized by their square shape. This head size increases the surface area of ​​the fastener and experiences a greater amount of friction, reducing the risk of loosening it.       
7. Wheel nuts:- Wheel nuts are a wide range of nuts used in automotive wheel applications.
8. Additional nut types:- Other walnut types that we can custom manufacture include hats, castles, conicals, caps, thumbs, and feathers.

Types of Washers:

Washers are disc-shaped components that provide controlled control of overlocking and friction when used with other fasteners. These fasteners may include dentures, indentations, and other unique structural mechanisms for use in more specific applications.

In general, they perform a variety of tasks, including loosening the fastener assembly, protecting the surface under a fastener, and evenly distributing pressure during installation and use.

Compared to nuts and bolts, washers are much less available. However, among the washer types, there are significant differences. Like the nuts, the washers should complement your selected bolt and suit your unique fastening application.

1. Beveled washers:- Beveled washers are made with a slightly angled surface, allowing them to join materials that are not parallel to each other.
2. Flat washers:- Flat washer is the most common type of washer. They provide larger surface areas for better load distribution. Different thicknesses are available for different types of hold strength.
3. Lock washers:- Lock washers come in many sizes, such as choppers, toothed rings, conical, or springs, each designed to prevent slippages of fasteners in demanding applications. They are commonly used in an environment that experiences a high degree of vibration.
4. Structural washers:- Structurals washers are one of the most heavy-duty washer options available. This thick fastener is designed to withstand the highs load pressures of construction.

FAQ: Bolts

What Is a Bolt?

A bolt is a mechanical fastener with a threaded shaft, typically used to join two parts together. It is inserted through aligned holes in the parts and secured with a nut to provide a clamping force and prevent axial movement.

How Does a Bolt Differ from a Screw?

The primary difference is in their usage. A bolt is generally used with a nut and is inserted through unthreaded holes, whereas a screw usually threads into one of the parts it is fastening. Bolts are used to join parts non-permanently, while screws can create a more permanent connection.

What Do the Numbers on a Bolt Grade Signify?

Bolts are classified by their strength using a two-number grading system. The first number represents the ultimate tensile strength (UTS) in MPa divided by 100, and the second number indicates the ratio of yield strength to UTS. For example, an 8.8 grade bolt has a UTS of 800 MPa and a yield strength of 80% of the UTS, which is 640 MPa.

What Are the Main Parts of a Bolt?

The main parts of a bolt are:

1. Head: The top part of the bolt that provides a gripping surface for tools.
2. Shank: The smooth, unthreaded part below the head that prevents radial movement.
3. Threading: The helical ridges on the bolt that allow it to engage with a nut or internal threads in the workpiece.

What Are Some Common Types of Bolts?

Common types of bolts include:

1. Carriage Bolt: Features a domed or countersunk head with a square underside, often used with wood and masonry.
2. Flange Bolt: Has an integrated flange that acts as a washer to distribute the load.
3. Hex Head Bolt: Characterized by a hexagonal head, widely used with wrenches.
4. Socket Head Cap Screw (Allen Bolt): Has a flat, chamfered top and is used in high-strength applications.
5. Square Head Bolt: Defined by its square head, allowing easy installation and tooling gripping.

What Types of Nuts Are Used with Bolts?

Nuts come in various types, including:

1. Coupling Nut: Connects two male threads or adds length.
2. Flange Nut: Has a flange for load distribution.
3. Hex Nut: A versatile, hexagon-shaped nut that requires a wrench for installation.
4. Locknut: Prevents other nuts from loosening, available with features like nylon inserts.
5. Square Nut: Provides a larger surface area for better friction and reduced risk of loosening.

What Are the Different Types of Washers?

Washers serve various functions, including load distribution and surface protection. Common types include:

1. Beveled Washers: Have an angled surface for joining materials that are not parallel.
2. Flat Washers: Provide a larger surface area for load distribution.
3. Lock Washers: Designed to prevent loosening in applications with high vibration.
4. Structural Washers: Heavy-duty washers for high load pressures in construction.

How Do I Choose the Right Bolt for My Application?

Selecting the right bolt depends on factors such as the material being fastened, the required strength, environmental conditions, and whether the connection needs to be permanent or removable. Consider these factors when choosing the type, size, and grade of the bolt.

Can Bolts Be Used in High-Vibration Environments?

Yes, bolts can be used in high-vibration environments, but it is important to use appropriate types, such as lock washers or specific locknuts, to prevent loosening due to vibrations.

Are There Custom Bolts Available?

Yes, many manufacturers offer custom bolts for specific applications, including various types like anchors, eye bolts, hook bolts, and T-handle bolts. Custom options can be tailored to meet particular strength and design requirements.