Carriage Bolt
Carriage bolts, also known as Coach Bolts, are specially designed for secure fastening in wood, metal, and composite structures. These bolts feature a round, dome-shaped head and a square neck, which prevents rotation during installation. This self-locking property ensures a tight and stable fit, making them ideal for construction, furniture assembly, fencing, and industrial applications.
Manufactured to meet ISO, DIN, and ASME standards, Rajal Industries’ Carriage Bolts provide exceptional strength, durability, and corrosion resistance while delivering an aesthetically smooth finish.
Head & Neck Design Specifications
Dome Head Profile
Provides a low-profile, smooth finish, making it ideal for safety-critical
applications such as playgrounds, furniture, and public infrastructure.
Reduces the risk of snagging, loosening, and accidental damage.
Square Neck Design
Prevents rotation of the bolt when tightened, ensuring a secure grip when inserted
into wood or pre-drilled square holes in metal.
Enhances vibration resistance, making it suitable for machinery, vehicles, and
structural connections.
Compatibility with Washers & Locking Nuts
Works well with flat washers, spring washers, and Nylock nuts to improve
fastening strength.
Helps prevent loosening in high-vibration applications such as automotive,
railways, and heavy machinery.
Thread Specifications & Precision Engineering
Carriage bolts are exposed to different environmental conditions, requiring the right
surface coating to enhance lifespan and prevent degradation.
| Thread Type | Description | Application |
|---|---|---|
| Coarse Thread (UNC/ISO Metric) | Standard thread, best for general- purpose fastening | Wood, construction, automotive |
| Fine Thread (UNF/Metric Fine) | Provides higher tensile strength & better load distribution | Machinery, aerospace, industrial equipment |
| Partially Threaded Bolts | Higher shear resistance, ideal for clamping applications | Structural assemblies, automotive |
| Fully Threaded Bolts | Maximum adjustability, even load distribution | General fastening, repair work |
Thread Fitment Precision
- Manufactured with ISO 6g tolerances, ensuring smooth engagement with nuts.
- Available in UNC (Unified National Coarse) and UNF (Unified National Fine) thread pitches for imperial sizes.
- Metric threads conform to ISO 261/965-1, ensuring compatibility with international applications.
Corrosion Resistance & Environmental Suitability
| Coating Type | Corrosion Protection Level | Ideal Applications |
|---|---|---|
| Plain Steel (No Coating) | Low | Indoor applications only |
| Zinc Plated (Yellow/Blue/White/Black) | Moderate (48-96 hours SST) | General use, low exposure to harsh environments |
| Hot-Dip Galvanized (HDG) | High (600+ hours SST) | Outdoor, marine, bridges, fencing |
| Black Oxide Coating | Medium corrosion resistance with a sleek appearance | Machinery, automotive |
| Geomet/PTFE Coatings | Extreme (1000+ hours SST) | Industrial, chemical, automotive |
SST = Salt Spray Test, measured in hours of corrosion resistance.
Salt Spray Testing
- All coated Carriage Bolts are tested per ASTM B117 and ISO 9227, ensuring long- term corrosion protection.
- HDG & PTFE-coated bolts offer enhanced resistance against marine and chemical exposure.
Sizes & Standards
| Size Range | Standards |
|---|---|
| Diameters: M5 to M24 (Metric) | ISO 7049-1 – Carriage bolts with metric specifications |
| Diameters: 1/4" to 1" (Imperial) | ASME B18.5 – American standard for carriage bolts |
| Lengths: Variable | DIN 603 – German standard defining dimensions for carriage bolts |
| ISO 8677 – Carriage bolts for wood & metal applications |
Material & Strength Grades
| Material Type | Available Strength Grades | Industry Standards |
|---|---|---|
| Mild Steel & Carbon Steel | 4.6, 5.6, 8.8 | ISO 898-1, DIN 603, ASME B18.5 |
| Stainless Steel (Corrosion Resistant) | A2-70 (SS 304), A4-80 (SS 316) | ISO 3506, DIN 603, ISO 8677 |
| High-Tensile Steel | Class 8.8, 10.9 | ISO 898-1, ASME B18.5, DIN 603 |
| Alloy Steel (Heat Treated) | Class 10.9 | ISO 898-1, ASTM A325 |
Common Applications of Carriage Bolts
- Wood & Timber Fastening – Used in wooden fencing, decking, and furniture assembly.
- Metal-to-Wood Connections – Secures frames, trailers, and structural components.
- Automotive & Heavy Vehicles – Essential for chassis components, truck beds, and suspension systems.
- Construction & Infrastructure – Used in bridges, railway tracks, and metal framing.
- Public Safety Installations – Ideal for playgrounds, benches, and guardrails due to their smooth, tamper-resistant design.
Why Choose Rajal Industries for Carriage Bolts?
Manufactured to International Standards
Ensuring dimensional accuracy, strength, and longevity.
Bulk & Custom Orders Available
Flexible manufacturing to meet your exact specifications.
High-Quality Material Selection
Ensuring long-lasting durability and reliability
Stringent Quality Control
Each bolt undergoes tensile testing, hardness testing, and thread fitment checks
Competitive Pricing & Timely Delivery
Efficient production and supply chain management
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Our Offices
C-204, Vaibhav Platina, Nr. Kaveri Trishra, S P Ring road, Shilaj, Ahmedabad, Gujarat-380054
Call us
+91-846 036 2030
Email Us
rajalfast@gmail.com sales@rajalindustries.com