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China Suppliers Factory DIN 6921 Flange Bolts - High-Performance Grade 4.8 to 12.9 for Durability and Strength
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China Suppliers Factory DIN 6921 Flange Bolts - High-Performance Grade 4.8 to 12.9 for Durability and Strength

Discover our high-quality flange bolts, manufactured in China by trusted suppliers and factories. Our flange bolts come in various grades, including 4.8, 8.8, 10.9, and 12.9, providing options for different strength requirements. Made from durable materials such as Q235, 35K, 45K, 40Cr, 20Mn Tib, 35Crmo, and 42Crmo, these bolts ensure reliability in various applications. We offer a range of surface treatments, including blackened, electrogalvanized, Dacromet, hot-dip galvanized, and standard galvanized finishes, enhancing corrosion resistance and longevity, A flange bolt features an integrated design that combines a hexagonal head with a flange plate, effectively securing parts that connect through holes. It works in conjunction with a nut to ensure firm fastening and stability. For premium flange bolts tailored to your specifications, choose our China factory as your go-to supplier.

    Surface treatment process

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    Flange bolt: A flange bolt is an integral bolt composed of a hexagonal head and a flange plate (the gasket below the hexagon and the hexagon are fixed together) and a screw (a cylindrical body with external threads). It needs to be matched with a nut and used to tighten the parts connecting two through holes. Therefore, bolt connection is a detachable connection.

    Classification

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    • 1 Hexagonal head type: one is flat headed, and the other is concave headed.
    • 2 Surface color category: According to different needs, the surface is coated with white, military green, colored yellow, and corrosion-resistant Dacromet.
    • 3 Category of flange: Depending on the location of the flange bolts used, the size requirements for the flange vary. There are also flat bottomed and toothed types, with toothed ones providing anti slip function.
    • 4 According to the force distribution of the connection: there are ordinary and hinged holes. The flange bolts used for hinged holes should match the size of the holes and be used when subjected to lateral forces.

    In addition, to meet the need for locking after installation, there are holes in the rod, which can prevent the bolt from loosening when subjected to vibration.

    Some flange bolts need to be made on the bare rod part without threads, called thin rod flange bolts. This type of flange bolt is beneficial for connecting under variable forces.

    Note: Commonly used national standard numbers in the market, GB5789 (large head) and GB16674 replace GB5787 (small head).

    Purpose

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    The flange bolt is composed of a hexagonal head and a flange plate, and its "support area to stress area ratio" is greater than that of ordinary bolts. Therefore, this type of bolt can withstand higher pre tightening force and has good anti loosening performance. Therefore, it is widely used in automotive engines, heavy machinery and other products.

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    Frequently Asked Questions

    What is a flange bolt?

    A flange bolt is an integral fastener consisting of a hexagonal head, a flange plate (which functions as a built-in washer), and a threaded screw. It is designed to be used with a nut to secure parts together through two aligned holes.

    What are the main classifications of flange bolt heads?

    Flange bolts are classified by their head style into two main types: flat-headed hexagonal types and concave-headed hexagonal types.

    What surface treatments are available for flange bolts?

    Depending on application requirements, flange bolts can be finished in various colors and coatings, including white, military green, colored yellow, and corrosion-resistant Dacromet.

    Why do some flange bolts have toothed flanges?

    Toothed flange bolts feature teeth on the bottom surface of the flange plate. These teeth provide an anti-slip function, preventing the bolt from loosening under vibration.

    Where are flange bolts commonly used?

    Due to their higher support-area-to-stress-area ratio, they can withstand higher pre-tightening forces and resist loosening. This makes them highly suitable for automotive engines, heavy machinery, and other high-stress applications.

    What are the common national standard numbers for flange bolts?

    In the market, the commonly used national standard numbers are GB5789 (large head) and GB16674, which replaces the GB5787 (small head) standard.