Hexagon Flange Head Bolt, Grade B

Hexagon Flange Head Bolt, Grade B — Product Introduction

Hexagon flange head bolt, Grade B is a fastener whose head is integrally formed by a hexagon head and a flange. Its flange design increases the bearing area, enables it to withstand higher preload, and provides excellent anti-loosening performance, usually without the need for an additional washer. This product is mainly manufactured according to standards such as GB/T 5787-1986 (standard series) or GB/T 5789-1986 (heavy series). Thread specifications cover M5–M20, the product grade is B, and common property classes include 8.8, 10.9, A2-70, etc. It is widely used in automobiles, machinery, construction, and other fields.

I. Product Features

• Integral flange face structure: The head is integrally formed by a hexagon head and a flange. The flange diameter and bearing area are relatively large, and the ratio of bearing area to stress area is greater than that of ordinary hexagon head bolts.

• Grade B accuracy and thread tolerance: The product grade is B, and the thread tolerance is 6g, suitable for mechanical connections with certain accuracy requirements.

• Complete specifications and performance: Thread specifications are M5, M6, M8, M10, M12, (M14), M16, M20; property classes include 8.8, 10.9, 12.9, and stainless steel A2-70.

• Diverse materials and surface treatments: Commonly used carbon steels (such as Q235, 45#, 40Cr, 42CrMo) and stainless steel; carbon steel parts can be treated by oxidation (blackening), zinc plating with passivation, color zinc plating, etc.

• Type A and Type B shank structures: The standard distinguishes two shank forms, Type A (straight shank) and Type B (reduced shank), which can be selected according to assembly requirements.

II. Product Advantages

• Excellent anti-loosening performance: The flange face increases the contact area and can effectively resist loosening caused by vibration, especially suitable for equipment and structures under vibration conditions, usually without additional spring washers or flat washers.

• Can withstand higher preload: The ratio of bearing area to stress area is larger, enabling the bolt to withstand higher preload and making the connection more reliable.

• Strong load-bearing capacity: Using materials such as 45#, 40Cr, and 42CrMo, the carbon steel version can reach a tensile strength of more than 700 MPa, and the alloy steel version can meet higher strength requirements.

• Convenient installation: It eliminates the washer assembly process, reduces the number of parts, improves assembly efficiency, and is suitable for automated assembly line operations.

• Good standardized interchangeability: As a national standard product, it has uniform dimensions and standardized marking (such as “Bolt GB 5789 M12×80”), and products from different suppliers can be used interchangeably.

III. Scope of Application

• Automotive industry: Key connection points such as engines, gearboxes, steering systems, powertrains, and body panels; this is the most core application scenario for hexagon flange head bolts.

• Heavy machinery and engineering equipment: Connections for mining machinery, crushers, rolling mills, cranes, and other equipment that withstand large loads and vibrations.

• General machinery and industrial equipment: Parts requiring high-strength, anti-loosening connections, such as pumps and valves, reducers, compressors, and automation equipment.

• Construction engineering: Steel structure connections, bridges, towers, and other occasions with requirements for connection reliability and anti-loosening performance.

• Home appliances and electronics: Fastening of sheet metal structures such as appliance housings, chassis, and cabinets, especially suitable for occasions requiring quick assembly without washers.