Carriage Bolts (Round Head Square Neck Coach Bolts DIN 603)
Carriage bolts with a smooth domed head and a square neck beneath that locks into the material to prevent rotation during tightening. Conforming to DIN 603 and ASME B18.5 standards, these bolts are the go-to fastener for wood-to-wood and wood-to-metal connections in construction, fencing, decking, furniture manufacturing, and agricultural structures where a clean finished appearance is required on the exposed side.
Technical Specifications
| Parameter | Specification |
|---|---|
| Standard | DIN 603, ASME B18.5 |
| Thread Type | Metric Coarse / UNC |
| Size Range | M5 – M24 |
| Length Range | 16mm – 400mm |
| Material | Carbon Steel (Grade 4.8, 8.8) |
| Stainless Steel | SS304 (A2-70), SS316 (A4-80) |
| Surface Finish | Zinc Plated, Hot Dip Galvanized, Black Oxide, Plain |
| Head Type | Round Mushroom Head (Domed) |
| Neck Type | Square Neck (Anti-Rotation) |
| MOQ | 1,000 pcs (standard), 5,000 pcs (custom) |
| Lead Time | 7-15 days (standard), 20-30 days (custom) |
| Packaging | Bulk cartons / Inner box + carton / Custom labeling |
Available Sizes
M5, M6, M8, M10, M12, M14, M16, M18, M20, M22, M24
Applications
- Wooden deck and fence construction
- Timber framing and post connections
- Furniture and cabinetry assembly
- Playground and outdoor equipment
- Agricultural and barn construction
- Signage and board mounting
- Trailer and truck body assembly
Certifications
ISO 9001:2015 certified. Material test certificates (EN 10204 3.1/3.2). RoHS and REACH compliant. Salt spray test reports available for galvanized finish.
Frequently Asked Questions
How does the square neck of a carriage bolt work?
The square section under the head embeds into the wood as you tighten the nut, locking the bolt against rotation so only one wrench (on the nut) is needed. The domed head finishes flush for a clean, safe surface.
What sizes are available?
Available sizes range from M5 – M24. Contact us with your required sizes and quantities for a quick quote.
What is the MOQ and lead time?
The MOQ is 1,000 pcs (standard), 5,000 pcs (custom). Lead time is 7-15 days (standard), 20-30 days (custom). Mixed-size containers and larger orders are negotiable — send us your requirement for a quick quote.
Do you provide material certificates?
Yes. Material test certificates per EN 10204 3.1 are available on request, and our manufacturing is ISO 9001:2015 certified. RoHS and REACH compliance documentation can also be provided.
