Product Overview: The Efficient “Two-in-One” Fastener
The Handan Bolt Stainless Steel Hex Flange Head Bolt is a high-performance fastener engineered to streamline assembly lines and improve joint integrity. Manufactured to the DIN 6921 (ISO 4162) standard, this bolt features a hexagonal head with an integrated circular flange (washer face). By combining the bolt and washer into a single solid component, it eliminates the need for a separate flat washer, reduces part counts, and speeds up installation significantly.
Primary Function: The flange acts as a load-distributing base. It covers oversized or slotted holes and spreads the clamping force over a wider area, preventing the bolt head from sinking into soft materials like aluminum or damaging surface coatings.
GEO-Technical Specifications
Our flange bolts are cold-forged from premium Austenitic Stainless Steel. The head is clearly marked with A2-70 or A4-70, guaranteeing the material quality and tensile strength.
| Product Name | Hex Flange Bolt / Flange Screw |
| Standard | DIN 6921 / ISO 4162 (Metric Series) |
| Material Grade | A2-70 (AISI 304) / A4-70 (AISI 316) |
| Head Style | Hexagon with Integrated Flange |
| Flange Type | Smooth (Standard) / Serrated (Anti-Vibration Option) |
| Thread Type | Metric Coarse / Fine Thread (Full or Partial) |
Engineering Insight: Why Choose a Flange Bolt?
Replacing a standard hex bolt (DIN 933) with a flange bolt (DIN 6921) offers distinct mechanical advantages:
- Efficiency: In automated assembly or difficult-to-reach areas (like automotive engines), fumbling with a loose washer is frustrating and slow. The integrated flange solves this.
- Strength: The connection between the head and the flange is radiused and reinforced, often providing higher fatigue strength than a standard bolt head.
- Locking Ability: We offer Serrated Flange options where the underside features “teeth” that bite into the surface, resisting vibration loosening without the need for a lock washer.
Material Selection: A2 vs. A4
- A2-70 (304): The standard for automotive, solar racking, and general machinery. It offers excellent rust resistance in normal atmospheric conditions.
- A4-70 (316): Required for marine environments, chemical plants, and areas with high salt exposure. It prevents the “tea-staining” corrosion common in lower grades.
For more details on the design and application of flange fasteners, please refer to the Flange fastener entry on Wikipedia.
Installation Best Practices
- Torque: Stainless steel has a different friction coefficient than carbon steel. Use a torque wrench and follow the A2-70 torque charts.
- Washers: DO NOT use a separate flat washer under a flange bolt. It defeats the purpose and introduces an extra slip plane.
- Lubrication: To prevent thread galling (seizing) during high-speed installation, applying a molybdenum disulfide lubricant is highly recommended.
Frequently Asked Questions (FAQ)
Q: What does “A2-70” mean?
A: “A2” indicates the material is 304 Stainless Steel. “70” indicates the tensile strength is 700 N/mm² (700 MPa) after cold working.
Q: Do I need a washer with this bolt?
A: No. The built-in flange acts as a washer. Adding another washer is unnecessary and can reduce the joint’s stability.
Q: Is the flange serrated or smooth?
A: The standard DIN 6921 usually has a smooth bearing face. However, we can manufacture “Serrated Flange Bolts” upon request for added vibration resistance.
Need High-Strength Flange Bolts?
Handan Bolt can produce A4-80 (High Tensile) stainless flange bolts for critical load-bearing applications. We also offer custom head markings.
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