Types of Bolts: 30 Different Bolts and Their Uses

Carriage bolts feature a dome-shaped, smooth upper body that’s flush-mounted, with a square-shaped lower part. These bolts lock themselves into similarly shaped cuts, allowing you to tighten them from the nut side only. Commonly used to fasten metallic objects to wood, carriage bolts are versatile and easy to install.

Anchor bolts are sturdy, heavy-duty bolts with a hexagonal top. Ideal for attaching thin objects to concrete slabs, they’re often used during construction to provide a secure foundation. They can be preset during the construction phase or installed later by penetration into cured material.

Hex bolts, also known as hex cap screws, are widely used in machinery and construction. They can be used with a nut or in a tapped hole. Fully threaded hex bolts are also known as tap bolts. Zinc-plated steel is a popular choice for hex bolts due to its low cost and moderate corrosion resistance.

Lag bolts, also known as lag screws, are large, heavy-duty bolts with hex heads. They are typically used to secure heavy timber and are ideal for projects like building decks or attaching heavy objects to wood.

Flange bolts are specialized types of bolts that evenly distribute force applied to them. The flange, located right beneath the bolt’s head, acts as a washer, providing additional support. These bolts are often used on frames of objects like beds, trucks, and are also suitable for vehicles and household appliances.

Shaped like the letter “J,” these bolts are used primarily in structural applications, such as securing walls to concrete foundations. The curved end hooks onto the material, providing a strong anchor.

Elevator bolts are uncommon both in use and structure. These bolts have a flat round head, distinctive washers, and a relatively long, threaded bottom, making them unique in appearance and function.

Hanger bolts are unique in that they don’t have a traditional head. Their entire body consists of two different threads, one end being flat and the other pointed. These bolts are primarily used for hanging items, though they can also be used to fix objects to timber.

Plow bolts resemble carriage bolts but with a completely flat upper head instead of a domed one. They’re often used in applications where a low-profile head is preferred, such as in agricultural equipment or where space is limited.

Wood screws have large threads and a relatively smooth shank, making them ideal for pulling two pieces of wood or similar materials together. They can be used in woodworking projects and other applications involving soft materials.

Socket screws are machine screws with an internal hex socket (Allen drive), allowing for easier tightening with a socket wrench. They’re often used in applications where space is limited or where high torque is required.

Sheet metal screws have sharp points and threads designed to be driven directly into sheet metal. They’re also suitable for use in dry conditions and softer materials like plastic, fiberglass, or wood.

Machine bolts have a flat, cylindrical head and are used with nuts to fasten metal parts together. They’re common in manufacturing and machinery.

T-bolts, also known as T-slot bolts, are designed with a “T” shape at one end, allowing them to be inserted into a T-slot for easy alignment and secure fastening. Commonly used in applications where the bolt needs to be inserted into a slot, like in woodworking or automotive industries.

Similar to hex bolts but without the shank, tap bolts are fully threaded and used in applications where a strong, secure hold is necessary, such as in machinery or automotive repairs.

U-bolts are shaped like the letter “U,” with two threaded legs that extend from a curved base. They’re commonly used to secure pipes, tubes, or other round objects to a flat surface. U-bolts are available in various sizes and materials, making them versatile for a wide range of applications.

Eye bolts feature a loop or “eye” at one end, allowing for easy attachment of ropes, cables, or chains. They’re commonly used in rigging, towing, and other applications where a secure connection point is needed. Eye bolts can be made from various materials, including stainless steel for corrosion resistance.

Shoulder bolts have a larger diameter section, called the shoulder, between the head and the threaded portion. This design allows for precise positioning and alignment of components. Shoulder bolts are often used in machinery and equipment where precise spacing is critical.

Structural bolts are designed for heavy-duty applications, such as connecting steel beams in buildings and bridges. They’re typically larger in diameter and have a higher tensile strength than standard bolts. Structural bolts require special installation techniques, including pre-tensioning, to ensure maximum strength and durability.

Security bolts are designed to deter tampering and unauthorized removal. They come in various forms, including one-way screws, tamper-resistant bolts, and bolts with special heads that require specialized tools for removal. Security bolts are commonly used in high-security applications, such as doors, windows, and safes.

Blind bolts are designed for use in situations where access to the far side of the material being fastened is limited or impossible. They’re often used in aerospace and automotive applications, where components need to be securely fastened within tight spaces.

Serrated flange bolts have a built-in washer with serrations that grip the surface, preventing loosening due to vibration. They’re commonly used in automotive and machinery applications.

Expansion bolts, also known as toggle bolts, use a mechanism that expands inside a hole to provide a secure anchor. They’re ideal for use in hollow walls or other materials where traditional screws or bolts cannot provide a solid grip.

Captive bolts are designed to stay attached to the component they are fastened to, preventing loss during maintenance. They’re commonly used in electrical and automotive applications.

Step bolts have a large, flat head, making them easy to install by hand. They’re often used in construction, particularly on steel structures like transmission towers.

Also known as Chicago bolts, these are two-part fasteners where one part is male-threaded and the other female-threaded, often used in binders, belts, and architectural applications.

These bolts have a slotted head and are often used in light-duty applications, such as attaching metal parts in appliances or sheet metal work.

Stainless steel bolts offer excellent corrosion resistance, making them suitable for outdoor and marine applications. They come in various grades, with higher grades indicating stronger, more hardened material (but also more brittle).

Lock bolts feature a locking mechanism that helps prevent loosening over time. They’re commonly used in applications where vibration or dynamic loads are present, ensuring a secure connection.

These bolts are welded directly onto a metal surface, providing a strong, permanent connection. They’re often used in construction and shipbuilding.