Surface Treatment Process & Overview
Flange bolt: A flange bolt is an integral fastener composed of a hexagonal head, a flange plate (where the gasket below the hexagon is integrally formed with the head), and a screw (a cylindrical body with external threads).
It is designed to be matched with a nut and utilized to firmly clamp and connect parts through two aligned through-holes. Consequently, a flange bolt connection provides a secure yet completely detachable mechanical connection.
Classification of Flange Bolts
1. Hexagonal Head Type
Includes two primary geometric configurations: flat-headed type and concave-headed type depending on engineering needs.
2. Surface Color Category
Available with diverse protective surface finishes, including white zinc, military green, colored yellow, and high corrosion-resistant Dacromet.
3. Category of Flange
Flange dimensions vary per application. Styles include smooth flat-bottomed types and serrated/toothed types that deliver enhanced anti-slip functionality.
4. Force Distribution Category
Categorized into ordinary connection bolts and hinged-hole bolts. Hinged-hole flange bolts match tight tolerance hole sizes to resist lateral shear forces.
Purpose & Engineering Applications
The flange bolt is composed of an integrated hexagonal head and flange plate. Because its "support area to stress area ratio" is significantly greater than that of ordinary bolts, it can withstand much higher pre-tightening force and provides superior anti-loosening performance.
Due to these mechanical advantages, flange bolts are extensively applied in demanding industrial environments, including automotive engines, heavy machinery, chassis assemblies, and other critical structural products.
Frequently Asked Questions
Q What are the main components of a flange bolt?
A flange bolt consists of a hexagonal head, an integrated circular flange plate base, and an externally threaded cylindrical shank.
Q Why do flange bolts provide better anti-loosening performance?
The enlarged flange base increases the support area to stress area ratio, allowing the fastener to endure higher pre-tightening torque and resist rotational loosening.
Q What surface treatment options are available for flange bolts?
Standard surface treatments include white zinc coating, military green coating, colored yellow passivated finish, and corrosion-resistant Dacromet plating.
Q What is the advantage of a toothed (serrated) flange?
A toothed or serrated flange grips into the mating surface material, providing strong anti-slip resistance against heavy vibration and dynamic stresses.
Q When are thin rod flange bolts recommended?
Thin rod flange bolts have an unthreaded section of reduced shank diameter, making them especially suitable for connections exposed to variable dynamic forces.
Q What are the primary GB standards for flange bolts?
The standard specifications commonly referenced are GB5789 for large head flange bolts and GB16674 (which replaces GB5787) for small head flange bolts.