M7 Hex Head Bolt – Professional Grade Fastening Solution for Heavy-Duty Industrial Applications
1. Product Overview
Our M7 hex head bolt is a precision-engineered fastening component designed for demanding industrial environments where reliability and tensile strength are non-negotiable. Manufactured from high-grade carbon steel, alloy steel, or stainless steel (304/316), this bolt features a standard hexagonal head for compatibility with common hand tools and power wrenches. The M7 thread size (7mm nominal diameter) fills a critical gap between M6 and M8 fasteners, offering a balanced load capacity for medium-to-heavy structural connections in machinery, automotive assemblies, and construction frameworks.
Each bolt undergoes strict dimensional inspection per ISO 4014 / DIN 931 standards, ensuring consistent thread pitch (1.0mm coarse) and head height. Available in plain, zinc-plated, hot-dip galvanized, or Dacromet finishes, this product resists corrosion in harsh environments while maintaining thread integrity under repeated torque cycles.
2. Key Features
- Precision Thread Geometry – Rolled threads with 6g tolerance class ensure smooth engagement with M7 nuts and tapped holes, reducing galling during assembly.
- High Tensile Strength – Property classes 8.8, 10.9, and 12.9 available, with yield strength up to 1,080 MPa for 12.9 grade.
- Corrosion Resistance – Optional zinc-nickel plating passes 720+ hours neutral salt spray testing (ASTM B117).
- Full Hex Head Design – Width across flats (WAF) of 11mm for standard socket compatibility, with chamfered edges to prevent wrench slippage.
- Consistent Hardness – Through-hardened core with surface hardness of 32-39 HRC (grade 10.9) prevents deformation under cyclic loading.
- Traceability – Laser-engraved grade markings and batch numbers on every M7 hex head bolt for quality control audits.
3. Technical Specifications
| Parameter | Value (Metric) | Notes |
|---|---|---|
| Thread Size | M7 × 1.0 | Coarse thread pitch |
| Head Type | Hexagon (DIN 931 / ISO 4014) | Full thread or partial thread options |
| Width Across Flats (WAF) | 11 mm | ±0.2 mm tolerance |
| Head Height (k) | 5.5 mm (for standard length) | Varies with bolt length |
| Thread Length (b) | Full thread: length ≤ 125 mm; Partial thread: b = 2d + 6 mm | Per DIN 933 (full) / DIN 931 (partial) |
| Property Classes | 8.8 / 10.9 / 12.9 | Carbon steel: 8.8-12.9; Stainless: A2-70, A4-80 |
| Proof Load (10.9 grade) | 830 MPa | Per ISO 898-1 |
| Surface Finish | Plain / Zinc / H.D.G. / Dacromet / Geomet | Custom coatings available |
| Operating Temperature | -50°C to +300°C (zinc); -50°C to +600°C (stainless) | Reduces with coating |
| Standards | DIN 931, DIN 933, ISO 4014, ISO 4017 | ANSI/ASME B18.2.1 variant available |
4. Application Scenarios
The M7 hex head bolt is widely adopted in sectors requiring robust, medium-sized fasteners:
- Agricultural Machinery – Securing blade assemblies, gearbox mounts, and tractor linkage points where vibration resistance is critical.
- Automotive Chassis & Suspension – Used for control arm brackets, shock absorber mounts, and engine crossmembers in light trucks and SUVs.
- Solar Panel Mounting Systems – Fixing aluminum rails to steel substructures, with stainless steel M7 bolts for outdoor UV and moisture resistance.
- Industrial Conveyor Systems – Attaching wear strips, roller brackets, and drive sprockets on assembly lines.
- Furniture & Racking – Heavy-duty shelving, workbench frames, and warehouse storage racks rated for 500+ kg capacity.
- Marine & Offshore – A4-80 stainless M7 hex head bolts for hatch covers, railing systems, and engine mounts on boats.
5. Advantages
- Space-Optimized Design – The M7 diameter provides 30% more shear strength than M6 while requiring only 1mm additional clearance, ideal for compact assemblies.
- Reduced Stripping Risk – Thread root radius optimization (per DIN 76) distributes stress more evenly than generic bolts, lowering field failure rates.
- Global Sourcing Compatibility – Meets both metric (ISO) and inch-based (ANSI) tooling standards; WAF 11mm matches 7/16″ wrenches for hybrid workshops.
- Cost-Effective Grade Options – Choose 8.8 for general use or 10.9 for high-stress applications without overspending on exotic alloys.
- Environmental Compliance – All coatings are RoHS and REACH compliant, with hexavalent-free chromium passivation available.
6. Why Choose Us
We are a direct manufacturer with over 18 years of experience in cold-heading and thread rolling for industrial fasteners. Our M7 hex head bolt line is produced in ISO 9001:2015 certified facilities with the following advantages:
- In-House Testing Lab – Every batch is verified via tensile testing (Zwick Roell), hardness testing (Rockwell), and salt spray chambers.
- Custom Lengths & Coatings – We offer M7 bolts from 12mm to 200mm length, plus specialized finishes like Xylan, PTFE, and zinc-flake.
- Bulk & Just-in-Time Delivery – Stock over 2 million pieces in standard sizes; custom orders ship within 10-15 working days.
- Technical Support – Our engineering team provides torque specifications, preload calculations, and assembly recommendations free of charge.
- Third-Party Certification – We provide material certificates (EN 10204 3.1) and batch traceability documentation upon request.
7. FAQ
Q: What is the torque specification for an M7 hex head bolt (grade 10.9)?
A: For a dry, unlubricated M7 bolt (grade 10.9), the recommended tightening torque is 28-32 N·m. With standard oil lubrication, reduce to 22-26 N·m. Always verify with a torque wrench and consider friction coefficient variations for coated bolts.
Q: Can I use an M7 bolt with an M8 nut?
A: No. M7 bolts require M7 nuts (thread pitch 1.0mm). Using an M8 nut (1.25mm pitch) will cause cross-threading and potential joint failure. Always match thread size and pitch exactly.
Q: What is the difference between DIN 931 and DIN 933 for M7 hex head bolts?
A: DIN 931 specifies a partial thread bolt (thread length b = 2d + 6mm), while DIN 933 is fully threaded. For applications requiring precise grip length (e.g., clamping thick flanges), choose DIN 931. For general fastening where full thread engagement is needed, select DIN 933.
Q: Do you offer M7 hex head bolts in stainless steel for food processing?
A: Yes. We supply A4-80 (316 stainless) M7 bolts that are passivated per ASTM A967 for food contact surfaces. These resist corrosion from acidic cleaning agents and high-pressure washdowns.
Q: How should I store M7 bolts to prevent rust?
A: Store in a dry environment (humidity < 60%) at 15-25°C. For zinc-plated bolts, keep in original anti-static bags. For stainless steel, avoid direct contact with carbon steel tools to prevent surface contamination and pitting.
Q: What is the minimum order quantity (MOQ) for custom-length M7 hex head bolts?
A: Our standard MOQ for custom lengths (non-stock sizes) is 5,000 pieces per dimension. For stock sizes (16mm to 100mm), we accept orders from 100 pieces with no MOQ surcharge.
