What Is a Carriage Bolt?
Carriage bolts, also known as coach bolts or plow bolts, are special fasteners used to securely hold materials together. They are easily recognizable by their smooth, rounded (domed) head and square neck directly beneath the head. This unique design allows the bolt to lock into place when inserted into pre-drilled square holes, preventing it from rotating when the nut is tightened.
Carriage bolts are commonly used in woodworking, metalworking, and construction, where a clean, snag-free surface is important. They are ideal for applications where the fastener needs to be concealed or where a smooth finish is essential.
Types of Carriage Bolts
Carriage bolts come in several types, each designed for specific applications. Below are the main types:
Long Neck Carriage Bolts
Long neck carriage bolts come with an extended neck, which is sometimes partially threaded. These bolts are ideal for connecting larger or thicker components. The extended neck offers more flexibility when fastening materials of varying thicknesses.
Standard (Square Neck) Carriage Bolts
These are the most commonly used carriage bolts. They have a round, domed head with a square neck underneath. Versatile and widely used, these bolts are ideal for general-purpose fastening in woodworking and construction projects. Available in materials like steel with zinc plating, galvanized, black oxide, and stainless steel finishes.
Ribbed Neck Carriage Bolts
Ribbed neck carriage bolts feature ribs or ridges around the neck, rather than the traditional square neck. This design improves grip and prevents the bolt from turning when tightened. Ribbed neck bolts are especially useful for applications that require additional stability, such as fastening sheet metal.
Short Neck Carriage Bolts
These bolts have a shorter neck, making them perfect for fastening thinner materials. They are typically used when a standard-length neck would be too long or obstructive. Short neck carriage bolts are suitable for medium to low-strength connections.
Choosing the Right Material for Carriage Bolts
Stainless Steel Carriage Bolts
Stainless steel is a great choice for carriage bolts that will be used outdoors or in marine environments. It resists rust and corrosion very well and gives a clean, shiny finish. Stainless steel bolts are often used in areas that face harsh weather or for decorative purposes. Common types include 304, 316, and duplex stainless steel, each with varying levels of corrosion resistance.
Carbon Steel Carriage Bolts
Carbon steel is known for its strength and toughness, making it ideal for heavy-duty applications. These bolts are usually coated with hot-dip galvanizing or black oxide to prevent rust and corrosion. Carbon steel bolts are widely used in industrial, automotive, and construction projects because they offer both strength and flexibility.
Aluminum and Brass Carriage Bolts
Aluminum and brass bolts are lighter, making them ideal when weight is a concern or when lower strength is acceptable. Aluminum bolts are especially useful in industries like aerospace, where lightweight components are essential. Brass bolts are often chosen for their decorative appearance and excellent resistance to corrosion.
How to Choose the Right Carriage Bolt？
Choosing the right carriage bolt is an important decision that depends on a few key factors. Here’s what you need to keep in mind:
First, think about the material you need. If the bolt will be exposed to the outdoors, stainless steel is your best bet because it resists rust and corrosion. This makes it ideal for marine environments or outdoor furniture. For industrial applications, carbon steel is a great choice, as it’s strong and more cost-effective. If weight is a concern, aluminum or brass bolts might be better. These materials are lighter while still offering reliable performance.
Next, consider the size of the bolt. Carriage bolts come in various lengths and diameters, so it’s crucial to choose the right one. To ensure a proper fit, check the size of the hole you are fastening. The diameter of the bolt should match the hole’s size, and the length should be long enough to go through the materials you’re joining. If you are working with thicker materials, you may need a longer bolt.
Lastly, think about the strength needed for your project. For heavy-duty applications that require a strong hold, carbon steel bolts are the way to go. They provide the strength needed for tough jobs. For lighter tasks, aluminum or brass bolts should suffice. If you’re uncertain about the required strength, it’s safer to opt for a stronger bolt to ensure a secure connection.
Common Uses of Carriage Bolts
Carriage bolts are highly versatile and widely used across different industries. Here are some of the most common applications:
Security Applications
Carriage bolts are also used in security applications. The square neck design prevents the bolt from being turned from the head side, which ensures the bolt can only be removed from the nut side. This feature makes them perfect for gates, fences, and other security-related structures.
Woodworking and Timber Construction
Carriage bolts are commonly used in woodworking projects such as decks, docks, outdoor furniture, and wooden bridges. Their smooth, rounded head ensures a clean, snag-free surface, which is essential in these types of applications.
Metal to Wood or Metal to Metal
These bolts are perfect for fastening metal to wood or metal to metal. They are often used in automotive assembly, trailer construction, and heavy machinery. The square neck prevents rotation, ensuring a strong and secure connection that holds up under stress.
Outdoor and Marine Applications
Stainless steel carriage bolts are particularly valuable in outdoor and marine environments where corrosion resistance is essential. They are commonly used in boats, docks, piers, and other structures exposed to water and harsh weather conditions.
Agricultural and Industrial Equipment
Carriage bolts are frequently used in agricultural machinery, industrial equipment, and infrastructure projects. Their durability and ability to create secure, long-lasting connections make them ideal for heavy-duty applications.
Playground Equipment
The smooth, domed head of carriage bolts is ideal for playground equipment, where safety is a top concern. This design reduces the risk of children’s clothing or skin getting caught, making carriage bolts the preferred choice for building play structures.
FAQ
Are there different grades of carriage bolts?
Yes, carriage bolts come in different grades, which refer to the strength of the bolt. Common grades include Grade 5 and Grade 8. Grade 8 bolts are stronger and typically used for high-stress applications.
What is Grade 8 carriage bolt?
A Grade 8 carriage bolt is a high-strength bolt commonly used in heavy-duty applications. It is made from alloy steel and has a higher tensile strength compared to standard bolts. These bolts are often used in automotive, industrial, and construction applications where maximum strength is required.
What are the types of bolts?
There are many types of bolts, including anchor bolts, arbor bolts, blind bolts, carriage bolts, elevator bolts, eye bolts, flange bolts, and serrated flange bolts.
When should I use a carriage bolt?
Carriage bolts should be used when a smooth, flush surface finish is needed, such as in furniture assembly, attaching metal brackets, or connecting wood to metal or wood to plastic.
What are the names of carriage bolts?
Carriage bolts are also known by several other names, including coach bolts, round head square neck bolts, mushroom head square neck bolts, dome head bolts, cup head bolts, and plow bolts.
Conclusion
Carriage bolts are an essential and versatile fastening solution used in a wide variety of industries. With their unique design, which prevents rotation and ensures a smooth, secure finish, they are ideal for woodworking, metalworking, construction, and outdoor applications. Whether you are working on a deck, assembling machinery, or building playground equipment, carriage bolts provide the strength and safety you need.
Contact Hengrui Fastener for Carriage bolt
For specialized applications that require custom solutions, Hengrui Fastener offers high-quality, customizable Carriage bolt and fasteners. Whether you need a specific size, material, or finish, Hengrui can provide tailored fasteners to meet your exact requirements. Contact Hengrui Fastener to learn more about our products and services.
