GB/T 6177 Hexagon Nuts with Flange，/DIN6923 Flange nuts with/without serration

Core Features

Integrated Flange Base – The flange is formed as a single piece with the nut body, eliminating the need for a separate washer. The underside of the flange incorporates a serrated bearing surface that provides locking action when tightened against the workpiece.

Hexagon Drive Configuration – The standard hexagon profile allows for installation using conventional open-end wrenches, socket wrenches, or ring spanners. The hexagon height is dimensioned to provide sufficient engagement for torque application while maintaining compact assembly geometry.

Serrated Locking Interface – The flange underside features a serrated design that creates mechanical interference with the mating surface during tightening, generating prevailing torque that resists loosening under vibration and dynamic loading conditions.

Product Characteristics

The fastener is produced in accordance with the dimensional and mechanical specifications defined in GB/T 6177. Thread dimensions and tolerances follow standard metric thread profiles according to GB/T 193 and GB/T 197. The flange outside diameter and thickness are dimensioned to provide adequate load distribution across the bearing surface. The flange underside angle and serration geometry are controlled to maintain consistent locking performance across repeated tightening cycles. Material composition and heat treatment processes are regulated to meet the mechanical property requirements for each specified performance grade. Surface treatment options include zinc plating, zinc flake coating (Dacromet), nickel plating, chrome plating, and phosphate coating, each applied according to defined coating thickness and corrosion resistance parameters.

Application Scenarios

Automotive Assembly – Applied in chassis components, engine mounting systems, and suspension assemblies where vibration-induced loosening is a primary concern. The integrated flange and serrated locking features reduce assembly time by eliminating separate washer handling.

Industrial Equipment Manufacturing – Used in machinery frames, gearbox housings, and pump assemblies where consistent clamping force is required and where the flange bearing surface provides load distribution without additional components.

Construction and Structural Applications – Employed in steel structure connections, scaffolding systems, and prefabricated building components where rapid assembly and vibration resistance are required.

Agricultural and Off-Highway Equipment – Utilized in heavy machinery subjected to shock loads and continuous vibration, where the flange and locking features contribute to joint integrity.

Customization Options

Specifications and configurations can be adjusted based on application requirements. Material grades include carbon steel grades (such as 8.8, 10.9) for general mechanical applications and stainless steel grades A2 and A4 for corrosion-resistant requirements. Surface treatments are selectable according to environmental exposure conditions, including coatings for salt spray resistance, chemical resistance, or specific aesthetic requirements. Strength grades can be matched to specific tensile and yield strength criteria defined in the application engineering specifications.

Frequently Asked Questions

Q: What is the difference between GB/T 6177 flange nuts and a standard hex nut with a flat washer?
A: The flange is integrally formed with the nut body, providing a fixed load-bearing surface that does not shift or separate during assembly. The serrated underside is optimized to provide locking action specific to the flange nut configuration, whereas a separate washer combination relies on the washer design for load distribution and does not provide the same integrated locking mechanism.

Q: Are GB/T 6177 nuts suitable for use on soft workpiece materials?
A: The flange bearing surface distributes clamping load over an increased area compared to a standard hex nut. This load distribution reduces the surface pressure applied to the workpiece and is suitable for use on materials where indentations from standard nut bearing surfaces may occur. For soft materials, material grade and flange dimensions should be evaluated against the specific application requirements.

Q: Can these nuts be reused after removal?
A: Reusability depends on the specific serration design and the application conditions. The flange serrations may experience wear or deformation during initial installation and removal, which can reduce locking performance in subsequent applications. For applications requiring multiple assembly cycles, locking performance should be verified through torque testing.

Q: What is the recommended tightening torque for GB/T 6177 nuts?
A: Tightening torque values are determined by the nut performance grade, thread size, material grade, and application load requirements. Torque specifications should be obtained from engineering standards or calculation methods defined in fastener design guidelines, considering friction conditions influenced by surface treatment and lubrication.

Q: Do these nuts require additional locking devices such as spring washers or threadlockers?
A: The serrated flange design provides a locking mechanism integrated into the nut. The use of additional locking devices depends on specific application requirements, including load conditions, vibration levels, and safety factors defined in the design specification. For critical applications, engineering evaluation should determine whether supplementary locking methods are required.

Installation Considerations

Torque application should follow specified tightening procedures. The serrated bearing surface engages the workpiece material upon initial contact, providing locking resistance. Over-tightening may deform the serration profile and reduce locking effectiveness, while under-tightening may not achieve full serration engagement. Thread condition affects torque-tension relationships; clean, dry threads without lubrication generally exhibit higher friction than lubricated threads. For plated or coated nuts, surface treatment thickness should be within specified tolerances to maintain thread fit and flange contact geometry. Inspection of flange underside condition is recommended before installation, as contamination or damage to the serrated surface may reduce clamping and locking performance.