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China Suppliers Factory Yellow Zinc Plated Hex Flange Bolt DIN6921 - Carbon Steel, Alloy, Stainless, Brass, Copper
Flange bolt, also known as flange bolt, is a special type of bolt with a flange surface (flange), widely used in situations that require high preload, anti-loosening, and sealing.
๐ฉ Structural Characteristics
๐ต Flange Surface Design
There is an integral flange (circular gasket) below the bolt head, which increases the contact area, disperses pressure, and reduces damage to the connection surface.
๐ง Hexagonal or Twelve Pointed Head
Commonly designed as a hexagonal head, easy to tighten with standard tools. Some high-strength models use twelve corner heads.
โ๏ธ Anti-Slip Tooth Pattern
The flange surface of some flange bolts has radial tooth patterns to enhance friction and prevent loosening.
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Main Advantages
๐ก No Need for Additional Gaskets
The integrated flange replaces traditional gaskets, simplifies installation steps, and reduces costs.
๐ก๏ธ Anti-Vibration & Anti-Loosening
The flange surface increases friction, and the tooth pattern design further prevents bolts from loosening in vibration environments.
โ๏ธ Uniform Force Distribution
The flange disperses the load, protects the surface of the connected parts, and avoids crushing or deformation.
๐ Sealing Enhancement
When combined with flange surfaces and soft materials such as rubber gaskets, the sealing performance can be improved.
๐ญ Common Application Areas
๐ Automotive Industry
Key parts such as the engine, gearbox, and wheel hub are adapted to high vibration environments.
๐๏ธ Machinery Manufacturing
Heavy equipment, machine tools, pumps, valves, and other connections that require high preload force.
๐ Architecture & Steel Structures
Wind and earthquake resistant structures such as bridges, steel frames, curtain walls, etc.
๐ Rail Transit
Scenarios with high requirements for safety and reliability, such as rail vehicles and signal equipment.
๐งฑ Material and Surface Treatment
๐ฉ Common Materials
- Carbon steel (e.g. Grade 4.8, 8.8, 10.9)
- Stainless steel (A2-304, A4-316, corrosion-resistant)
- Alloy steel (high-strength or high-temperature resistant)
๐ ๏ธ Surface Treatment
- Galvanized (conventional anti-corrosion)
- Dacromet (high corrosion resistance)
- Hot dip galvanizing (heavy-duty anti-corrosion, suitable for outdoor use)
- Phosphating (enhancing wear resistance)
โ Frequently Asked Questions
Q What is the difference between a flange bolt and a regular bolt?
A flange bolt features an integrated flange (washer-like ring) beneath the bolt head. This built-in flange increases the bearing surface area, eliminates the need for a separate washer, and provides better anti-loosening performance compared to standard bolts.
Q Do flange bolts require additional washers or gaskets?
In most cases, no. The integrated flange acts as a built-in washer, distributing the clamping load and reducing the need for additional gaskets. However, in specific sealing applications, a soft gasket (such as rubber) may still be used in combination.
Q What materials are flange bolts commonly made from?
Flange bolts are commonly manufactured from carbon steel (grades 4.8, 8.8, 10.9), stainless steel (A2-304 or A4-316 for corrosion resistance), and alloy steel for high-strength or high-temperature applications. The choice of material depends on the working environment and load requirements.
Q Why are flange bolts preferred in the automotive industry?
Flange bolts are widely used in automotive applications โ including engines, gearboxes, and wheel hubs โ because their tooth-patterned flange surface significantly resists loosening under high vibration conditions, ensuring long-term joint reliability and safety.
Q What surface treatments are available for flange bolts and which is best for outdoor use?
Common surface treatments include galvanizing (standard anti-corrosion), Dacromet (high corrosion resistance), hot dip galvanizing (heavy-duty protection), and phosphating (improved wear resistance). For outdoor or harsh environments, hot dip galvanizing or Dacromet coating is generally recommended for superior corrosion protection.
Q Can flange bolts be used in structural and civil engineering applications?
Yes. Flange bolts are suitable for structural and civil engineering uses such as bridges, steel frames, and curtain wall systems. Their ability to distribute load evenly and resist loosening under dynamic forces makes them a reliable choice for wind and earthquake-resistant structures.