Types of Bolts: A Complete Visual Guide for Engineers and Buyers

Bolts have several types in different grades, each designed specifically for a particular application, joint, and loading condition. 

Understanding the types of bolts will enable engineers and buyers to select the appropriate bolt the first time without trial and error.

The types of bolts are categorized into general-purpose bolts, specialty bolts, industrial bolts, and automotive bolts. Pictures of different types of bolts make it easy to identify which type of head to use on a project.

General Purpose Bolts (Hex, Carriage, Lag)

General purpose bolts can be used for almost all construction projects and repairs. They are usually supplied in bulk with nuts, as these are commonly found with a variety of uses.

Hex Bolts

Hex bolts feature six sides in their head, making them easy to grip with either a wrench or a socket. They comply with ASME B18.2.1 standards regarding dimensions of threads and heads.

Hex bolts can be used in a variety of steel structure works, machinery, and assembly operations. To find some of your hex bolts, check out the CNXD hex bolts product category page.

Carriage Bolts

Carriage bolts feature smooth round heads and a squared neck underneath. The squared neck of carriage bolts keeps them from rotating when the nut is being screwed.

Lag Bolts

Lag bolts possess coarse threads along with a point and are similar to a large wood screw. The lag bolt is screwed directly into wood or masonry without requiring a nut at the other end.

Specialty & Shape-Specific Bolts (U-Bolt, Eye Bolt, J-Bolt, T-Bolt)

For some applications, there may be a requirement for a bolt of special form to do the job. The problem cannot be handled by ordinary hex or carriage bolts.

U-Bolts & J-Bolts

U-bolts make a ‘U’ form that surrounds pipes, tubing, and round stock to hold the object in position on both sides. J-bolts resemble U-bolts except that they make an arch on one end only. They are used to anchor equipment in concrete.

Eye Bolts

Eye bolts feature a loop on their head instead of a hex or square. This loop will hold a hook, rope, or chain, thus making eye bolts popular in rigging applications.

T-Bolts

T-bolts have a T-shaped head that slides into a matching slot, often on machine tables or extruded aluminum framing. CNXD’s T-bolts line supports this kind of slotted assembly work.

Industrial & Heavy-Duty Bolts (Anchor, Stud, Shoulder)

Industrial use requires bolts that can handle greater loading, more severe conditions, or are installed in fixed locations. Industrial bolt types, along with their corresponding nuts, have been designed to last a long time under stress.

Anchor Bolts

Anchor bolts are placed into the concrete while it is still wet, thus forming a fixed location for columns, machinery, or support structures. These bolts can bear both tensile and shear loads once the concrete has hardened.

Stud Bolts

Stud bolts have threads on both ends and no head at all. One end threads into a tapped hole or flange. A nut secures the other end, which is common in piping and flange connections.

Shoulder Bolts

The shoulder bolt features a smooth and accurately machined shaft beneath the head and is commonly employed as a point of pivoting or a spacer.

Automotive Bolts (Wheel, Hub, Camber, Cylinder Head)

There are bolts that are resistant to vibrations, heat, and torqueing without becoming loose. In many cases, automotive bolts are tested according to OEM specifications prior to being assembled into vehicles.

Wheel and Hub Bolts

Wheel and hub bolts hold together wheel assemblies within vehicles and transfer all weight and torque during driving processes. Wheel and hub bolts usually comply with strict grades and torque values specified by vehicle manufacturers.

Camber Bolts

Also known as eccentric bolts, camber bolts permit minute adjustments to wheel alignment. The technician simply turns the offset head of the bolt to change the wheel angle to an extent.

Cylinder Head Bolts

The cylinder head bolts fasten the engine head to the block. They keep the pressure of combustion sealed inside the engine block. Due to the immense pressure on them, they require strong material like high-tensile alloy steel.

How to Choose the Right Bolt Type for a Project

Picking the correct bolt starts with the load type, the base material, and how often the joint needs servicing. A quick checklist helps narrow down the options before placing an order.

Consider these factors together rather than picking based on price alone. Getting the match right the first time avoids costly failures or repeat orders later.

Suppliers that stock complete types of bolts and nuts kits make ordering easier. One purchase covers the fastener and its correct mating hardware.

• Load direction, whether shear, tension, or a mix of both.
• Base material, such as steel, concrete, wood, or aluminum.
• Environment, including moisture, temperature, and vibration exposure.
• Head style needed for tool access and clearance.
• Required grade or certification for the industry involved.

For slotted or grooved assemblies, check a supplier’s Allen bolts and flange bolts categories too. These pages can reveal head styles better suited to tight spaces.

Bolt Selection Comparison Table

This table works alongside the types of bolts with pictures shown throughout this guide. It offers a fast reference for common categories, typical use, and key traits.

Industrial bolt types such as anchor and stud bolts often carry different certification needs than automotive bolts, so checking specifications before ordering matters. 

Suppliers serving export markets typically document material certifications and grade markings for each batch. This helps buyers confirm parts meet project requirements without guesswork.

Choosing among the many types of bolts becomes easier once the load, material, and industry standard are clear. 

Matching the bolt to the job, rather than defaulting to a familiar style, keeps assemblies safer. It also reduces the chance of early fastener failure.