Key Features of Carriage Bolts: Round Head and Square Neck

Carriage bolts are commonly used in wood structures, furniture frames, and outdoor installations. While they may appear simple at first glance, the combination of a round head and square neck makes them highly functional in real-world applications.

As a professional carriage bolt manufacturer, Xinchi is proud to explain how these features work, helping buyers and engineers select the right bolt and avoid common installation issues.

Round Head Design of Carriage Bolts and Its Function

The most noticeable feature of a carriage bolt is its round, domed head. Unlike hex bolts, it has no external driving faces, which brings several benefits:

• Safety: The smooth head reduces the risk of scratches or injuries when touched, making it suitable for furniture, playgrounds, or wooden structures.
• Appearance: The round head looks neat and blends well with the surface, keeping installations visually clean.
• Pressure Distribution: When tightened, the head distributes the load evenly across the wood surface, minimizing damage and indentations.

Square Neck Design and Anti-Rotation Performance

Right under the round head is the square neck, which is the key functional element of a carriage bolt.

When inserted into a pre-drilled hole, the square neck bites into the wood, locking the bolt in place and preventing it from rotating while tightening the nut on the other side. This design allows installation with access from only one side and ensures the bolt stays fixed over time.

How Round Head and Square Neck Work Together

The combination of the round head and square neck gives carriage bolts their strength and reliability:

• The round head provides a smooth, safe surface
• The square neck anchors the bolt firmly inside the wood
• The nut and washer on the opposite side generate a secure clamping force

This makes carriage bolts ideal for wood-to-wood and wood-to-metal connections, where both stability and appearance matter.

Applications of Carriage Bolts

Carriage bolts are particularly suitable for wood and soft materials. Common uses include:

• Furniture frames and chairs
• Fences, decks, and pergolas
• Playground equipment and outdoor installations
• Wooden pallets and packaging

In these scenarios, the round head ensures safety and visual appeal, while the square neck keeps the bolt securely in place.

Xinchi Fasteners Factory Advantage

At Xinchi Fasteners, we focus on high-quality fasteners for industrial and furniture applications. Our advantages include:

• Over 102 cold heading machines with a daily output exceeding 10 million pieces, ensuring supply stability
• A modern factory covering 30,000 m², including two six-story production buildings
• Full range of standard and custom carriage bolts, with consistent quality control and competitive pricing

Xinchi is a trustworthy fastener company. We have a factory that was founded in 2007. We are the designated fastener supplier to“STAPLE”. As a trusted fastener supplier, we offer a wide range of high-quality fasteners, including nuts, screws, bolts, rivets, and washers. Our products are widely used in automotive, machinery, construction, electronics, and furniture industries, trusted by global customers for stability, precision, and durability.

With Xinchi, customers get reliable, durable carriage bolts suitable for a wide range of applications, backed by professional production capacity and experience.