DIN 603 Round Head Square Neck Bolts

DIN 603 is an international standard that defines the specifications for round head square neck bolts, commonly known as carriage bolts. These bolts feature a smooth, dome-shaped head and a square neck just below the head, which helps prevent rotation during installation. They are widely used in woodworking, construction, and mechanical assemblies where a secure and tamper-resistant fastening is required.

Key Features

✅ Round (Dome) Head Design

Provides a smooth and aesthetically pleasing finish.
Prevents loosening due to external impacts or friction.

✅ Square Neck Feature

Designed to fit into square holes or embed into wood/metal for self-locking.
Prevents the bolt from rotating during tightening.

✅ Material Options

Carbon Steel – Ideal for general construction applications.
Stainless Steel – Offers high corrosion resistance for outdoor and marine environments.
Galvanized Steel – Provides enhanced durability and rust protection.

✅ Industry Applications

Woodworking & Furniture – Commonly used in wooden structures for a secure, non-rotating fit.
Construction & Bridges – Ideal for steel-to-wood or wood-to-wood connections.
Automotive & Machinery – Used in fastening components where tamper resistance is needed.
Railway & Infrastructure – Ensures strong structural connections in railways and heavy-duty installations.

DIN 603 Standard Specifications

Property	Specification
Head Type	Round (Dome)
Neck Type	Square
Thread Type	Metric (Coarse & Fine)
Strength Classes	4.6, 5.6, 8.8 (for carbon steel)
Surface Treatment	Zinc-plated, Hot-dip galvanized, Black oxide, etc.

Advantages of DIN 603 Bolts

✔ Prevents Rotation – The square neck locks into place, preventing unwanted movement.
✔ Tamper-Resistant – The smooth, round head cannot be easily loosened with standard tools.
✔ High Load Capacity – Suitable for heavy-duty applications requiring strong connections.
✔ Corrosion Protection – Available in stainless steel and coated finishes for outdoor durability.