Automotive Dark Olive-Drab Distorted-Thread Flange Lock Nuts – 720h NSS

Automotive Dark Olive-Drab Distorted-Thread Flange Lock Nuts with 720-Hour Neutral Salt Spray Performance

DIN 6927 / DIN EN 1664 All-Metal Prevailing-Torque Flange Nuts for Automotive OEM Applications

JUXIN FASTENERS supplies carbon steel distorted-thread flange lock nuts for automotive manufacturers,

 Tier-1 and Tier-2 suppliers, industrial equipment manufacturers and global OEM procurement teams.

The featured automotive fasteners have a distinctive dark olive-gray metallic appearance and are associated with a surface treatment specification capable of achieving 720 hours of neutral salt spray (NSS) exposure.

This combination of an all-metal prevailing-torque locking mechanism, 

an integrated bearing flange and a corrosion-resistant surface treatment makes the product relevant to automotive mechanical assemblies exposed to vibration, 

moisture, road contamination and changing environmental conditions.

In the American industrial fastener market, these products are commonly described as Distorted-Thread Flange Nuts, 

All-Metal Prevailing-Torque Flange Nuts, Deformed-Thread Flange Locknuts or All-Metal Self-Locking Flange Nuts.

The original product standard reference is DIN 6927, with DIN EN 1664 and ISO 7044 providing related international specifications.

Unlike conventional nylon-insert flange lock nuts, these fasteners generate prevailing torque through a controlled metallic interference feature.

For automotive OEM applications, performance must be evaluated as a complete fastening system, including the nut, mating bolt, surface treatment, friction characteristics, installation torque and joint design.

JUXIN FASTENERS supports engineering drawing review, custom surface treatment requirements and bulk production inquiries for industrial OEM supply programs.

Product Overview and Technical Specifications

Product Name: Automotive Dark Olive-Drab Distorted-Thread Flange Lock Nuts

Primary American Industry Name: Distorted-Thread Flange Nuts

Alternative Industry Names:

• All-Metal Prevailing-Torque Flange Nuts

• Deformed-Thread Flange Locknuts

• Automotive All-Metal Lock Nuts

• All-Metal Self-Locking Hex Flange Nuts

• Prevailing-Torque Hexagon Flange Nuts

• Nylon-Free Flange Lock Nuts

Material: Carbon Steel

Original Listed Property Classes:

• Property Class 8

• Property Class 10

Original Listed Metric Sizes:

• M5

• M6

• M8

• M10

• M12

• M14

• M16

• M20

Visible Surface Appearance: Dark Olive-Gray / Dark Olive-Drab Metallic Finish

Corrosion Performance Capability: 720 Hours Neutral Salt Spray (NSS)

Salt Spray Test Reference: ISO 9227, where specified by the customer

Actual Coating Chemistry: Subject to Approved Plating Specification

Original Product-Family Coating Options:

• Clear Zinc Plating

• Blue-Passivated Zinc Plating

• Yellow Zinc Plating

• Black Zinc Plating

• Zinc-Nickel Alloy Plating

• Zinc-Flake Coating

• Dacromet-Type Coating, Subject to Specification

The actual coating used on the featured automotive product must be confirmed from the plating process documentation.

Original Standard: DIN 6927

Related Product Standards:

• DIN EN 1664

• ISO 7044

Relevant Functional and Material Standards:

• ISO 2320

• ISO 898-2

Relevant Coating and Corrosion Test Standards:

• ISO 9227

• ISO 4042

• ISO 19598

• ISO 10683, where zinc-flake coatings are specified

• ASTM F1941/F1941M, where applicable to the customer specification

The applicable standard editions, dimensions, property classes, coating specifications and performance acceptance criteria must be confirmed for each OEM order.

What Are Automotive Distorted-Thread Flange Nuts?

Distorted-thread flange nuts are all-metal self-locking fasteners designed to generate prevailing torque through controlled metallic interference.

A portion of the nut's thread or body is intentionally deformed during manufacturing.

When the nut engages a compatible mating bolt, the interference feature creates resistance to rotation.

This resistance is called prevailing torque.

The locking feature helps resist unintended rotation under suitable operating conditions.

The integrated flange provides a larger bearing surface than a comparable non-flanged hex nut.

These characteristics make the fastener suitable for evaluation in automotive mechanical assemblies where vibration resistance, compact fastening geometry and corrosion protection are important.

However, prevailing torque alone does not guarantee that a bolted joint will remain secure.

Correct bolt preload, joint stiffness, mating materials, installation conditions and mechanical validation remain essential.

720-Hour Neutral Salt Spray Performance

The featured automotive fastener is associated with a surface treatment capable of achieving 720 hours of neutral salt spray exposure.

Neutral salt spray testing is widely used to evaluate the corrosion resistance of protective coatings on metallic components.

For automotive fasteners, this type of testing can support coating qualification and comparative corrosion performance assessment.

What Does 720 Hours NSS Mean?

A 720-hour NSS requirement indicates that the coated component is evaluated under a specified neutral salt spray exposure for 720 hours.

The test is generally conducted according to an agreed procedure, such as ISO 9227.

The result must be interpreted using the relevant acceptance criteria.

Important distinctions include:

• Time to first white corrosion.

• Time to first red rust.

• Permitted corrosion area.

• Corrosion on significant surfaces.

• Corrosion around threads.

• Corrosion on bearing surfaces.

• Appearance after exposure.

• Customer-specific acceptance requirements.

A 720-hour exposure duration does not automatically establish 720 hours without red rust or white corrosion.

The exact acceptance condition should be defined in the customer specification and verified by the relevant test report.

Why 720-Hour NSS Performance Matters for Automotive OEMs

Automotive fasteners may be exposed to:

• Rainwater.

• Road spray.

• Road salt.

• Condensation.

• Moisture accumulation.

• Dirt and debris.

• Temperature fluctuations.

• Outdoor storage conditions.

• Vehicle washing chemicals.

A corrosion-resistant coating system can help protect carbon steel fasteners under suitable service conditions.

For OEM programs, the corrosion requirement should be evaluated alongside the mechanical and assembly requirements.

Neutral Salt Spray Testing vs. Real-World Corrosion

Neutral salt spray testing is an accelerated laboratory test.

It is useful for evaluating coating performance under controlled conditions.

However, 720 hours of laboratory salt spray exposure cannot be converted directly into a specific number of years of vehicle service.

Actual corrosion behavior depends on:

• Climate.

• Road salt exposure.

• Temperature.

• Humidity.

• Coating damage.

• Joint geometry.

• Contact with other materials.

• Maintenance conditions.

For demanding automotive programs, additional cyclic corrosion or customer-specific environmental tests may be required.

Automotive Dark Olive-Drab Surface Appearance

The featured flange nuts have a dark gray metallic appearance with an olive-green tone.

In American industrial finishing terminology, related color descriptions may include:

• Olive Drab Finish

• Dark Olive Drab

• Olive-Gray Metallic Finish

• Dark Passivated Zinc Finish

• Black Zinc-Nickel Finish

These terms do not necessarily identify the same coating process.

A dark olive appearance may result from different coating and post-treatment systems.

The actual plating chemistry must be confirmed from the supplier's approved process specification.

Olive-Drab Zinc Plating

Olive-drab zinc plating is a recognized historical surface finish description in the North American fastener market.

It may involve zinc electroplating followed by a colored conversion coating.

Some traditional olive-drab conversion coatings used hexavalent chromium chemistry.

For modern automotive applications, environmental compliance must be evaluated against the current customer and regulatory requirements.

The visible color alone cannot establish whether a coating is Cr(VI)-free.

Black Zinc-Nickel Electroplating

Black zinc-nickel electroplating is another relevant automotive coating technology.

Depending on the approved system, zinc-nickel electroplating may be combined with passivation and sealing treatments.

Potential advantages include:

• Corrosion protection.

• Controlled coating thickness.

• Automotive surface treatment compatibility.

• Customer-specific appearance.

• Compatibility with selected friction-control topcoats.

Actual performance depends on the complete coating system.

The featured product should not be labeled as black zinc-nickel plated until the process has been verified.

Trivalent Passivation and Cr(VI)-Free Coatings

Modern automotive programs frequently specify environmentally compliant surface treatment systems.

Depending on the customer specification, requirements may include:

• Cr(VI)-free passivation.

• Restricted substance compliance.

• REACH requirements.

• RoHS requirements, where applicable.

• Customer-specific material declarations.

• Approved coating chemistry.

A 720-hour NSS result does not automatically prove environmental compliance.

The coating chemistry and supporting documentation must be evaluated separately.

ISO 19598 and Automotive Zinc Alloy Electroplating

ISO 19598 addresses zinc and zinc-alloy electroplated coatings on iron or steel with Cr(VI)-free treatment.

It provides a relevant technical framework for evaluating certain automotive electroplated coating systems.

For OEM sourcing, the approved coating specification should identify:

• Coating metal or alloy.

• Coating thickness.

• Passivation system.

• Sealer or topcoat.

• Corrosion requirements.

• Friction requirements.

• Environmental compliance.

The exact ISO coating designation should be taken from the customer drawing or approved plating specification.

ISO 4042 and Electroplated Fasteners

ISO 4042 is relevant to electroplated coating systems for fasteners.

For prevailing-torque flange nuts, coating requirements must be coordinated with:

• Thread fit.

• Coating thickness.

• Mechanical properties.

• Hydrogen embrittlement considerations.

• Installation friction.

• Prevailing torque.

A coating system should not be selected based only on appearance or corrosion exposure duration.

Coating Thickness and Thread Fit

Coating thickness affects the dimensional relationship between the nut's internal thread and the mating bolt.

For a distorted-thread flange nut, this is particularly important because the locking mechanism already creates controlled thread interference.

Excessive or inconsistent coating thickness may affect:

• Thread engagement.

• Prevailing-on torque.

• Prevailing-off torque.

• Installation effort.

• Mating thread wear.

• Assembly repeatability.

The coating process must be compatible with the specified thread geometry and locking performance.

Coating Friction and Automotive Assembly Torque

Automotive OEMs may specify friction characteristics to support controlled tightening and consistent clamp force.

The friction behavior of a coated fastener can depend on:

• Coating type.

• Passivation.

• Topcoat.

• Lubrication.

• Mating bolt coating.

• Thread geometry.

• Bearing surface condition.

• Installation speed.

For prevailing-torque nuts, friction and locking resistance must be considered together.

A coating that meets a 720-hour NSS requirement may still require additional validation before being approved for an existing assembly.

Hydrogen Embrittlement Considerations

Certain electroplating processes can introduce hydrogen into susceptible steel fasteners.

Hydrogen embrittlement risk depends on:

• Material strength.

• Heat treatment.

• Manufacturing processes.

• Plating method.

• Process control.

• Applicable standards.

For automotive property class 10 nuts, coating selection and process controls should be reviewed against the relevant engineering requirements.

Corrosion performance alone does not establish that a coating process is suitable for every high-strength fastener.

How the Distorted-Thread Locking Mechanism Works

The locking feature is created by controlled metallic deformation.

When the nut engages the bolt, the deformed section generates additional resistance to rotation.

This resistance is present before the nut reaches the joint bearing surface.

Prevailing-On Torque

Prevailing-on torque is the resistance encountered while installing the nut before significant clamp force develops.

Prevailing-Off Torque

Prevailing-off torque is the resistance encountered during removal after clamp force has been relieved.

Clamp Force

Clamp force is generated by bolt tension and compresses the joined components.

Important Engineering Principle

Prevailing torque is not equivalent to clamp force.

A properly designed automotive joint must account for both the locking feature and the required preload.

DIN 6927, DIN EN 1664 and ISO 7044

DIN 6927

DIN 6927 is the historical German standard designation associated with all-metal prevailing-torque hexagon flange nuts.

It remains familiar to European automotive procurement and engineering teams.

DIN EN 1664

DIN EN 1664 replaced the earlier DIN 6927 designation in the German standard system.

It addresses prevailing-torque all-metal hexagon nuts with flange.

ISO 7044

ISO 7044 specifies prevailing-torque all-metal hexagon nuts with flange, style 2, for metric sizes M5 through M20.

Dimensional Compatibility

Although these standards address related products, they should not be treated as automatically interchangeable in every dimension.

For automotive replacement or production transfer programs, verify:

• Thread size.

• Thread pitch.

• Width across flats.

• Nut height.

• Flange diameter.

• Flange geometry.

• Locking feature.

• Property class.

• Coating specification.

• Assembly clearance.

Historical DIN-to-EN/ISO conversions may involve dimensional differences, including certain hexagon dimensions.

The approved OEM drawing remains the controlling document.

ISO 2320 Prevailing-Torque Requirements

ISO 2320 provides functional requirements and testing methods for prevailing-torque steel nuts.

Relevant performance characteristics include:

• Prevailing-on torque.

• Prevailing-off torque.

• Repeated installation and removal performance.

• Proof-load-related requirements.

• Torque and clamp-force behavior.

For automotive OEM programs, prevailing-torque testing should be coordinated with the coating and mating bolt specification.

A change in coating can affect the measured locking behavior.

All-Metal Flange Lock Nuts vs. Nylon-Insert Flange Lock Nuts

Both designs are used to resist unintended loosening.

However, their locking mechanisms are different.

All-Metal Distorted-Thread Flange Nuts

• Use metallic interference.

• Do not contain a nylon insert.

• May be considered for selected elevated-temperature applications.

• Require appropriate prevailing-torque control.

• Can experience reduced locking torque after repeated use.

Nylon-Insert Flange Lock Nuts

• Use a polymer insert.

• Have temperature limitations associated with the insert.

• May have different installation characteristics.

• Require evaluation of environmental compatibility.

The correct fastener depends on the joint design, operating temperature, vibration and service requirements.

Neither type should be described as universally superior.

Integrated Flange and Bearing Surface

The integrated flange provides a larger bearing area than a comparable non-flanged hex nut.

Potential engineering benefits include:

• Wider bearing contact.

• Reduced need for a separate plain washer in suitable designs.

• Lower loose-component count.

• Simplified assembly handling.

• Compatibility with selected automated assembly processes.

However, the flange must fit the actual mating surface.

The engineer should verify:

• Hole diameter.

• Flange diameter.

• Bearing area.

• Edge distance.

• Surface flatness.

• Mating material strength.

• Assembly clearance.

A flange does not automatically make an oversized or damaged hole acceptable.

Property Class 8 and Property Class 10

The original product range includes property classes 8 and 10.

Property Class 8

Class 8 nuts may be selected for appropriate industrial bolted joints where the specified mechanical requirements are satisfied.

Property Class 10

Class 10 nuts may be selected for certain higher-strength bolted joints requiring the corresponding nut mechanical properties.

Mating Bolt Compatibility

Nut property class should be coordinated with:

• Bolt property class.

• Thread specification.

• Required preload.

• Joint loading.

• Fatigue requirements.

• Operating environment.

• Installation method.

A property class 10 nut may be relevant to certain applications using compatible property class 10.9 bolts.

However, bolt compatibility and tightening requirements must follow the applicable standards and joint engineering design.

Available Metric Thread Sizes

The original product range includes:

• M5

• M6

• M8

• M10

• M12

• M14

• M16

• M20

Common ISO metric coarse-thread designations for reference include:

• M5 × 0.8

• M6 × 1.0

• M8 × 1.25

• M10 × 1.5

• M12 × 1.75

• M14 × 2.0

• M16 × 2.0

• M20 × 2.5

These are standard thread references rather than confirmation of every available product combination.

Actual thread pitch, tolerance class and product standard must be confirmed for each order.

Metric vs. UNC and UNF Threads

American automotive and industrial buyers may search for comparable locking flange nuts using UNC or UNF terminology.

However, the featured range is metric.

Metric, UNC and UNF threads are not directly interchangeable.

For example:

• M6 is not interchangeable with 1/4"-20 UNC.

• M8 is not interchangeable with 5/16"-18 UNC.

• M10 is not interchangeable with 3/8"-16 UNC.

Requests for inch-series locking flange nuts must be evaluated separately.

Automotive Applications and Engineering Solutions

1. Automotive Chassis-Associated Brackets

Automotive chassis assemblies may contain mechanical brackets and support components exposed to vibration.

Engineering Challenge

Vibration and dynamic loading may contribute to unintended fastener rotation if the joint is not properly designed.

Potential Solution

A distorted-thread flange nut can provide a metallic prevailing-torque locking feature.

For exposed locations, a 720-hour NSS coating requirement may also support the corrosion-protection specification.

The final joint requires customer-specific validation.

2. Automotive Underbody Equipment

Underbody components may encounter road spray, moisture, salt and debris.

Potential applications include:

• Equipment mounting brackets.

• Protective panel hardware.

• Mechanical support components.

• Auxiliary fastening assemblies.

Engineering Challenge

Corrosion exposure and vibration may occur together.

Potential Solution

A corrosion-protected all-metal flange lock nut may be evaluated where the specified coating, locking performance and mechanical properties satisfy the OEM requirements.

A 720-hour NSS capability should be assessed against the actual corrosion acceptance criteria.

3. Automotive Body Hardware

Automotive body assemblies may use locking fasteners for selected mechanical components.

Engineering Challenge

The fastener may require a controlled external appearance, consistent assembly torque and corrosion resistance.

Potential Solution

A dark olive-gray finish can be specified together with the required mechanical and coating performance.

Color consistency should be evaluated separately from corrosion resistance.

4. Automotive Exterior Accessories

Exterior accessories may be exposed to rain, washing chemicals and temperature changes.

Engineering Challenge

The joint requires suitable mechanical retention and environmental compatibility.

Potential Solution

An all-metal flange lock nut with an approved corrosion-protection system may be considered.

The required coating performance and joint retention must be validated for the application.

5. Electric Vehicle Mechanical Assemblies

Electric vehicles incorporate numerous mechanical support and enclosure assemblies.

Potential applications include:

• Equipment mounting brackets.

• Auxiliary structural supports.

• Mechanical enclosure hardware.

• Selected battery-adjacent mechanical supports.

Engineering Challenge

The assembly may require vibration resistance and corrosion protection.

Potential Solution

A property-class-appropriate distorted-thread flange nut may be evaluated according to the OEM drawing.

Electrical insulation, thermal runaway protection and battery safety requirements must be addressed separately.

6. Automotive Thermal Management Equipment

Automotive cooling and thermal management systems may contain mechanical supports exposed to vibration and temperature changes.

Potential applications include:

• Cooling equipment brackets.

• Auxiliary mounting hardware.

• Mechanical support frames.

Engineering Challenge

Temperature variation and vibration may affect joint behavior.

Potential Solution

An all-metal prevailing-torque nut may be evaluated where its material, coating and joint design are suitable.

7. Commercial Vehicle Equipment

Commercial vehicles may encounter demanding road and environmental conditions.

Potential applications include:

• Mechanical brackets.

• Equipment supports.

• Auxiliary hardware.

• Selected mounting assemblies.

Engineering Challenge

The joint may experience vibration, moisture and repeated mechanical loading.

Potential Solution

A corrosion-resistant distorted-thread flange nut may be evaluated against the applicable vehicle engineering specification.

8. Agricultural and Off-Highway Vehicles

Agricultural and off-highway equipment may operate in wet, dusty and vibration-intensive environments.

Engineering Challenge

Environmental exposure and repeated loading can affect fastener reliability.

Potential Solution

An all-metal flange lock nut with a specified corrosion-protection system may be considered.

The actual coating must be validated for the expected service environment.

9. Heavy Equipment and Construction Machinery

Heavy equipment may use locking fasteners for selected mechanical supports and accessories.

Engineering Challenge

Dynamic loads and environmental exposure can affect joint retention.

Potential Solution

A distorted-thread flange nut may be evaluated according to property class, coating performance and joint design.

Safety-critical applications require dedicated engineering approval.

10. Rail and Transportation Equipment

Rail equipment manufacturers may require corrosion-protected locking hardware for selected mechanical assemblies.

Engineering Challenge

Vibration and long maintenance intervals can increase the importance of joint reliability.

Potential Solution

An all-metal prevailing-torque flange nut may be considered where the applicable rail and equipment requirements permit.

Rail-specific approvals and test requirements must be confirmed separately.

11. Industrial Machinery and Automation

Industrial machinery may contain vibration-exposed bolted connections.

Potential applications include:

• Equipment frames.

• Mechanical brackets.

• Machine guards.

• Auxiliary support structures.

Engineering Challenge

Repeated operation can affect joint retention.

Potential Solution

A distorted-thread flange nut can be evaluated as part of the complete mechanical joint.

12. HVAC and Cooling Equipment

HVAC equipment may contain fans, pumps and mechanical supports exposed to vibration.

Engineering Challenge

Vibration and environmental exposure may affect fastening reliability.

Potential Solution

A suitable all-metal flange lock nut with the required coating may be considered.

13. AI Data Center Mechanical Infrastructure

AI data centers contain extensive mechanical infrastructure for cooling and power distribution equipment.

Potential applications include:

• Cooling equipment brackets.

• Mechanical rack accessories.

• Auxiliary support frames.

• Equipment mounting hardware.

Engineering Challenge

Mechanical equipment may require stable fastening performance over extended operating periods.

Potential Solution

A properly specified prevailing-torque flange nut may be evaluated for selected mechanical joints.

This does not imply qualification for all structural or electrical data center applications.

14. Power Distribution and Electrical Equipment

Electrical infrastructure includes mechanical support assemblies and equipment enclosures.

Engineering Challenge

The joint may be exposed to vibration, temperature variation or moisture.

Potential Solution

A coated all-metal flange lock nut may be evaluated for appropriate mechanical fastening requirements.

Electrical conductivity, grounding and insulation requirements must be addressed separately.

Automotive Installation Torque Engineering

All-metal prevailing-torque nuts require special attention to tightening behavior.

The installation procedure should account for:

• Mating bolt property class.

• Nut property class.

• Thread size and pitch.

• Prevailing-on torque.

• Bearing friction.

• Thread friction.

• Surface coating.

• Required clamp force.

• Final tightening torque.

• Tool calibration.

• Joint geometry.

Why Generic Torque Tables May Be Inadequate

Generic tightening tables may not account for the actual prevailing-torque feature or coating friction.

For automotive OEM applications, tightening specifications should be validated using the actual nut, bolt, coating and joint components.

Automated Assembly and Production Engineering

For production managers, the fastener must perform consistently during automated or semi-automated assembly.

Relevant considerations include:

• Nut feeding.

• Part orientation.

• Thread starting.

• Cross-threading prevention.

• Run-down torque.

• Prevailing-torque variation.

• Final tightening control.

• Tool capacity.

• Assembly cycle time.

• Inspection.

• Rework.

• Traceability.

A coating change may require renewed assembly validation if it affects friction or prevailing torque.

Can Automotive Distorted-Thread Flange Nuts Be Reused?

Repeated installation and removal may reduce the prevailing-torque locking performance.

Reuse should be based on:

• Applicable standard requirements.

• OEM specifications.

• Prevailing-off torque measurements.

• Thread condition.

• Coating condition.

• Number of installation cycles.

• Joint criticality.

• Maintenance procedures.

A nut should not be reused solely because it can still be threaded onto a bolt.

The approved OEM maintenance specification should determine whether reuse is permitted.

Common Engineering Problems and Solutions

Problem 1: Insufficient Prevailing Torque

Possible causes include locking feature variation, repeated use or thread wear.

Review the specified prevailing-torque requirements and test results.

Problem 2: Excessive Installation Torque

Possible causes include excessive interference, coating friction or incompatible mating threads.

Review thread compatibility and the coating specification.

Problem 3: Inconsistent Clamp Force

Possible causes include friction variation, coating differences or unsuitable tightening procedures.

Review the complete torque/clamp-force relationship.

Problem 4: Coating Damage During Assembly

Possible causes include tooling contact, high friction or incompatible installation conditions.

Review tooling and coating durability.

Problem 5: Corrosion After Salt Spray Exposure

Possible causes include coating defects, inadequate thickness, surface damage or unsuitable process controls.

Review the coating specification and corrosion test acceptance criteria.

Problem 6: Thread Damage

Possible causes include cross-threading, incompatible bolt threads or incorrect installation procedures.

Review mating hardware and assembly controls.

Problem 7: Joint Loosening Under Vibration

Possible causes include inadequate preload, joint settlement, dynamic loading or insufficient locking performance.

Evaluate the complete joint rather than relying only on the prevailing-torque feature.

Quality Inspection and OEM Validation

Quality requirements should follow the approved engineering drawing and customer specification.

1. Dimensional Inspection

Potential inspection characteristics include:

• Thread diameter.

• Thread pitch.

• Nut height.

• Width across flats.

• Flange diameter.

• Flange thickness.

• Bearing surface geometry.

• Locking feature geometry.

• Critical tolerances.

2. Mechanical Property Verification

Verify the specified nut property class and applicable proof-load requirements.

3. Prevailing-Torque Testing

Depending on the applicable specification, testing may include:

• Prevailing-on torque.

• Prevailing-off torque.

• Repeated installation/removal performance.

• Torque/clamp-force behavior.

4. Coating Inspection

Potential requirements include:

• Coating type.

• Coating thickness.

• Surface appearance.

• Passivation.

• Sealer or topcoat.

• Corrosion resistance.

• Friction characteristics.

• Environmental compliance.

5. Neutral Salt Spray Testing

The featured automotive coating specification is associated with 720 hours of neutral salt spray exposure.

Testing should define:

• Applicable test method.

• Exposure duration.

• Sample preparation.

• Significant surfaces.

• Corrosion acceptance criteria.

• White corrosion requirements.

• Red rust requirements.

• Test report format.

The 720-hour capability should be verified against the approved customer acceptance criteria.

6. Thread Inspection

Inspection procedures must account for the prevailing-torque locking feature.

7. Functional Assembly Validation

The complete fastening system may require evaluation of:

• Mating bolt compatibility.

• Installation torque.

• Clamp force.

• Locking performance.

• Coating integrity.

• Vibration performance.

• Environmental durability.

These are potential OEM validation requirements rather than claims that every test is routinely performed on every production lot.

Automotive PPAP and Quality Documentation

Automotive OEM and Tier-1 programs may require structured quality documentation.

Depending on the customer requirements, this may include:

• Approved engineering drawings.

• Material specifications.

• Dimensional inspection reports.

• Mechanical property test reports.

• Prevailing-torque test reports.

• Coating specifications.

• Coating thickness reports.

• Neutral salt spray test reports.

• Friction test reports.

• Material compliance declarations.

• First article inspection.

• Production traceability.

• Process control documentation.

• PPAP submissions.

• Engineering change control.

Specific certifications, approvals or PPAP submission levels must be confirmed for each project.

Production Management and Total Cost of Ownership

For production managers and procurement teams, the value of an automotive locking nut includes more than its unit price.

Relevant factors include:

• Material cost.

• Coating cost.

• Corrosion performance.

• Prevailing-torque consistency.

• Installation efficiency.

• Tooling compatibility.

• Inspection requirements.

• Scrap and rework.

• Packaging.

• Traceability.

• Delivery performance.

• Repeat-order consistency.

A qualified coating system may help meet the required corrosion specification.

However, the total cost should be evaluated together with assembly efficiency and field performance.

Custom Automotive Distorted-Thread Flange Nuts to Engineering Drawings

JUXIN FASTENERS supports technical inquiries for standard-based and customer-specific all-metal flange lock nuts.

Custom requirements may include:

• Metric thread size.

• Thread pitch.

• Property class.

• Hexagon dimensions.

• Flange geometry.

• Locking feature design.

• Prevailing-torque performance.

• Dark olive-drab surface appearance.

• Specified electroplated coating systems.

• Zinc-nickel coating requirements.

• Coating thickness.

• 720-hour NSS performance.

• Corrosion acceptance criteria.

• Friction requirements.

• Environmental compliance.

• OEM inspection requirements.

• Packaging.

• Production quantity.

Manufacturing feasibility and quotation depend on the approved technical specifications.

Frequently Asked Engineering Questions

What are automotive distorted-thread flange nuts?

They are all-metal prevailing-torque flange nuts that use controlled metallic deformation to resist unintended rotation on compatible bolts.

What is the American name for DIN 6927 flange lock nuts?

Common American terms include Distorted-Thread Flange Nuts and All-Metal Prevailing-Torque Flange Nuts.

What does 720-hour NSS mean?

It refers to 720 hours of neutral salt spray exposure under a specified test method and acceptance criteria.

Does 720-hour NSS mean 720 hours without red rust?

Not automatically. The acceptable corrosion condition must be defined in the customer specification and supported by test results.

Is the featured coating black zinc-nickel?

The photographed product has a dark olive-gray appearance. The exact coating chemistry must be confirmed from the approved plating specification.

What is olive-drab plating?

Olive-drab is a recognized finish color description associated with certain zinc coating and conversion coating systems.

Are olive-drab zinc plating and black zinc-nickel plating the same?

No. They can use different coating chemistries, passivation systems and corrosion-protection technologies.

Can these nuts be supplied with Cr(VI)-free coatings?

Customer requirements for Cr(VI)-free coating systems can be evaluated according to the approved specification and available manufacturing processes.

What is ISO 9227?

ISO 9227 specifies salt spray test methods used for corrosion testing of metallic materials and protective coatings.

What is ISO 2320?

ISO 2320 addresses functional requirements and test methods for prevailing-torque steel nuts.

What is the relationship between DIN 6927 and DIN EN 1664?

DIN EN 1664 replaced the historical DIN 6927 designation. Dimensional compatibility must be checked against the relevant standard editions.

What is ISO 7044?

ISO 7044 specifies prevailing-torque all-metal hexagon nuts with flange, style 2.

What property classes are listed?

The original product range includes Property Class 8 and Property Class 10.

What sizes are listed?

M5, M6, M8, M10, M12, M14, M16 and M20.

Can these nuts be used in automotive chassis assemblies?

They may be suitable for selected applications when the mechanical, corrosion and assembly requirements are satisfied and the joint is approved by the OEM.

Are these nuts suitable for high-temperature applications?

All-metal designs may be considered for selected elevated-temperature applications, but the actual temperature capability depends on the material, coating and joint requirements.

Can distorted-thread flange nuts be reused?

Reuse depends on the applicable standard, customer requirements and remaining prevailing-torque performance.

Do these nuts eliminate the need for washers?

The integrated flange may eliminate a separate plain washer in some designs, but not every application.

Can metric flange nuts be installed on UNC bolts?

No. Metric and UNC threads are not directly interchangeable.

Can JUXIN FASTENERS evaluate custom automotive coating specifications?

Yes. Customer-specific surface treatment and performance requirements can be reviewed against the engineering drawing and production specifications.

What information is needed for an automotive OEM quotation?

A dimensioned drawing, standard designation, material and property class, thread size, coating specification, prevailing-torque requirements, corrosion acceptance criteria and production volume provide a useful basis for technical review.

Request an Automotive Distorted-Thread Flange Nut RFQ

JUXIN FASTENERS supports engineering and procurement inquiries for automotive all-metal distorted-thread flange lock nuts with customer-specified corrosion-protection systems.

For a new OEM program or an existing production component, please provide:

• 2D engineering drawing or 3D CAD file.

• Required DIN, EN or ISO standard and edition.

• Metric thread size and pitch.

• Required property class.

• Mating bolt specification.

• Nut and flange dimensions.

• Prevailing-torque requirements.

• Installation torque or clamp-force requirements.

• Surface coating specification.

• Dark olive-drab appearance requirement, if applicable.

• Coating chemistry and thickness.

• Neutral salt spray requirement, including 720-hour NSS where specified.

• White corrosion and red rust acceptance criteria.

• Friction coefficient requirements.

• Environmental compliance requirements.

• Operating temperature and service environment.

• Quality and inspection requirements.

• PPAP or other automotive documentation requirements, where applicable.

• Initial order quantity.

• Estimated annual production demand.

• Target delivery schedule.

Our team can review the supplied technical specifications and discuss engineering clarification, manufacturing feasibility and quotation.

JUXIN FASTENERS

Website: https://www.juxinfasteners.com/

Email: info@juxinfasteners.com

Submit Your Engineering Drawings for a 720-Hour NSS Automotive Distorted-Thread Flange Nut RFQ.

Packaging Standard

At Juxin Fasteners, we apply standardized export packaging to ensure product protection, traceability, and compliance with international logistics requirements.

1. Standard Export Packaging

Unless otherwise specified, all products will be packed according to our factory standard export packaging, which includes:

Moisture-resistant inner protection

Poly bag or small box packing as required

Reinforced export cartons

Clear labeling with part number, specification, batch number, and quantity

Palletizing for sea or air shipment when necessary

Our standard packaging is designed to ensure safe transportation, efficient warehousing, and long-distance international shipping.

2. Customized Packaging Options

We also provide customized packaging solutions according to customer requirements, including but not limited to:

Private labeling

Customized barcodes

Specific carton dimensions

Retail packaging

Special pallet configuration

Customer-specific marking and identification

So that you know, customized packaging may involve additional costs and extended lead time depending on the complexity of the requirements.

3. Compliance & Quality Assurance

All packaging processes are controlled under our ISO 9001 quality management system to ensure consistency, traceability, and product integrity throughout the supply chain.