GB/T 6182 Hexagon Nuts with Non-Metallic Insert (Type 2)

Core Features

Non-Metallic Nylon Insert – A captive nylon washer mounted in the upper portion of the nut creates a compression grip on the threads of the mating fastener, generating prevailing torque that resists loosening . The nylon material also provides a gas and moisture seal at the fastener interface .

Type 2 Hexagon Configuration – The nut is dimensioned in accordance with Type 2 specifications, equivalent to GB/T 6175 with the addition of the prevailing torque locking feature . The hexagon profile allows installation using standard wrenches and sockets.

Prevailing Torque Locking Mechanism – The nylon insert generates friction during installation, providing consistent locking torque without the need for supplementary locking devices such as spring washers, threadlockers, or adhesives.

Product Characteristics

The fastener is produced in accordance with the dimensional and mechanical specifications defined in GB/T 6182-2000. Thread dimensions and tolerances follow standard metric thread profiles. Nut height and hexagon dimensions are maintained to Type 2 specifications, providing increased nut height compared to Type 1 configurations .

The non-metallic insert is manufactured from polyamide (nylon 6/6) material positioned to create an interference condition with the male threads. The locking torque generated by the insert is controlled through insert geometry and positioning parameters to meet prevailing torque requirements defined in the standard.

Material composition and heat treatment processes are regulated to meet the mechanical property requirements for performance grades 9 and 12. Grade 9 provides defined proof load and tensile strength specifications, while Grade 12 offers increased strength for heavy-duty applications. Stainless steel grades A2 and A4 are available for corrosion-resistant requirements.

Surface treatment options include zinc plating, zinc flake coating, nickel 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 powertrain assemblies where vibration-induced loosening is a primary concern. The nylon insert provides locking action without the need for supplementary locking devices.

Industrial Equipment Manufacturing – Used in machinery frames, pump assemblies, and motor mounts where consistent clamping force is required and where the locking mechanism prevents loosening under dynamic loading.

Aerospace and Defense – Employed in applications requiring prevailing torque locking features with non-metallic inserts, as specified in military standards .

General Engineering Applications – Utilized in through-hole fastening configurations where the nut is accessible for installation and where the locking mechanism provides resistance to rotational loosening .

Customization Options

Specifications and configurations can be adjusted based on application requirements. Material grades include carbon steel for general applications and stainless steel grades A2 and A4 for corrosion-resistant requirements. Surface treatments are selectable according to environmental exposure conditions, including zinc plating with various chromate finishes, zinc flake coating, nickel plating, and phosphate coating. 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 6182 and GB/T 889.1?
A: GB/T 6182 covers Type 2 non-metallic insert hexagon lock nuts with performance grades 9 and 12 . GB/T 889.1 covers Type 1 configurations with different dimensional and performance specifications. The Type 2 configuration provides increased nut height and higher strength grades.

Q: What is the temperature rating for nylon insert lock nuts?
A: The nylon insert materials (typically polyamide/nylon 6/6) have temperature limitations. The nominal temperature rating is 250°F (121°C) . Temperatures exceeding this rating may result in degradation of the non-metallic insert and loss of locking torque.

Q: Can these nuts be reused after removal?
A: Reusability depends on the condition of the nylon insert and the application's locking torque requirements. The insert may experience wear or deformation during installation and removal, which can reduce locking performance in subsequent applications. For critical applications requiring multiple assembly cycles, locking torque should be verified against the specified requirements.

Q: Are these nuts suitable for use with chemicals?
A: The non-metallic nylon insert has chemical compatibility limitations. Certain chemicals may cause degradation of the insert material, affecting locking performance . Chemical compatibility should be evaluated based on the specific chemical exposure conditions.

Q: What is the recommended tightening torque for GB/T 6182 nuts?
A: Tightening torque values are determined by the nut performance grade, thread size, material grade, and application load requirements. The nylon insert generates additional friction during installation; torque specifications should account for the prevailing torque contribution. Torque specifications should be obtained from engineering standards or calculation methods defined in fastener design guidelines.

Q: Do these nuts require additional locking devices?
A: The non-metallic insert provides the locking mechanism. 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

The nylon insert creates resistance during thread engagement; installation speed should be controlled to prevent galling or overheating of the insert material . If galling occurs during installation, reducing installation speed should be considered. Thread condition before installation should be evaluated; damaged or contaminated threads may affect locking torque performance.

For plated or coated nuts, coating thickness should be maintained within specified tolerances to ensure thread fit and consistent insert engagement. For stainless steel nuts, passivation treatment should be performed per ASTM A380 . Inspection of the nylon insert condition is recommended before installation; damaged or displaced inserts may not provide the specified prevailing torque.