Round head carriage bolts, also known as round head square neck bolts or carriage screws, were originally used to join iron and wood parts in carriages. It is a fastener consisting of a semicircular head, cylindrical threaded rod and integrally molded square neck. Generally used in conjunction with nuts, its square neck design prevents the bolt from rotating after installation. They are often used in situations where space is limited or a smooth appearance is required.
The series of round head bolts include: large semi-circular head carriage bolts, small semi-circular head square neck bolts, mushroom head square neck bolts, cup head square neck bolts, short square neck bolts with round head, ribbed neck carriage bolts, round head ribbed neck bolts, round head bolts with round head necks, 114° countersunk square neck bolts and so on.
Specifications
| Diameter | M6-M24 (1/4″-1″) |
| Length | 20mm-300mm (3/4″-12″) |
| Thread Type | UNC thread, UNF thread, ISO thread, Metric thread, Imperial thread, Full thread, Half thread, Coarse thread, Fine thread |
| Head Height | Standard is 0.6 times the bolt diameter |
| Material | Carbon Steel, Alloy Steel, Stainless Steel, Brass, Titanium Alloy |
| Strength | Grade 4.6，6.8，8.8，10.9，12.9; A2-70, A2-80, A4-70, A4-80 |
| Standard | DIN, ISO, JIS, BS, ASME, UNI. |
| Packing | Small Box + Carton +Pallet, Custom Packaging Service |
How to Measure a Carriage Bolt?
- Length (L): The total length from the top of the head to the bottom of the threaded rod.
- Thread diameter (D1): The diameter of the external thread.
- Neck width (L1): The width of the neck.
- Neck height (H): The height of the neck.
- Head height (T): The thickness of the head.
- Head diameter (D): The diameter of the round head.
Surface Finishing
- Galvanizing (Electro-galvanizing / Hot-dip Galvanizing)
- Dacromet (Zinc-Aluminum Flake Coating)
- Chrome Plating
- Black Oxide Coating
- Powder Coating
- Nickel Plated
- Tin Plated
- Passivation
Standards
| DIN 603 | DIN 21547 | DIN 5903 | ASME B 18.5 | ASME B 18.10 | UNI 573 |
| DIN 11015 | ISO 8677 | BS 4933 | JIS B 1171 | GOST 7802 | NF E 27-351 |
| DIN 607 | ISO 8678 | BS 325 | JIS E 1107 | GOST 11530 |
Types of Round Head Carriage Bolts
Grade 8.8 Carriage Bolt Nut Set
Stainless Steel Carriage Bolt
Brass Round Head Square Neck Bolt
Carbon Steel Carriage Bolt
Application Fields
- Construction industry: wood structure connection, metal frame fixing
- Furniture manufacturing: high-grade furniture assembly
- Automotive industry: body and chassis parts fixing
- Railway industry: track equipment installation
- Agricultural machinery: equipment assembly and maintenance
- Shipbuilding: deck fixing and interior structure
- Equipment: playground equipment, mining equipment
- Construction machinery: large excavators, loaders, shovels
Our Service Advantage
51Fasteners is a professional supplier of round head square neck bolts with a complete supply chain system for fast delivery. Through efficient process and service, we create more value for our customers.
- Customized size and non-standard specification production
- Special material and alloy manufacturing
- Various surface treatment customization
- Small sample and high volume production
- Marking and branding
- Heat treatment and strength enhancement services