Countersunk Head Steel Locking-Collar Rivets (Flush Head Lockbolts)

Countersunk Head Steel Locking-Collar Rivets and Flush Head Lockbolts for OEM Structural Assemblies

Product Overview

JUXIN FASTENERS supplies countersunk head steel locking-collar rivets, also known as flush head steel lockbolts or countersunk ring-groove fasteners, for industrial OEM manufacturing and permanent metal assemblies.

These fasteners combine a countersunk steel pin with a compatible steel locking collar to create a mechanically locked connection.

The countersunk head is designed to fit into a correctly prepared countersink in the joined component. Where the head geometry and countersink dimensions are properly matched, the installed pin head can sit flush with the surrounding surface.

During installation, dedicated lockbolt tooling draws the joint together and swages the collar into the locking grooves of the pin.

Unlike conventional blind rivets, typical two-piece locking-collar fasteners require access to both sides of the assembly.

Countersunk steel lockbolts may be considered for industrial applications requiring permanent fastening, a recessed head profile and verified mechanical joint performance.

Actual pin and collar materials, dimensions, strength, surface finish and installation requirements must be confirmed against the approved engineering specification.

Product Identification and Specifications

The JX-D-L-ST reference identifies the steel material family in the supplied JUXIN documentation. The exact countersunk-head configuration and corresponding collar must be confirmed by the approved drawing or product-specific part number.

Engineering Solution 1 — Countersunk Head Design

The defining characteristic of this product is its countersunk pin head.

A countersunk head is intended to seat within a matching conical recess in the connected material.

When the fastener and countersink are correctly specified, this configuration can provide a flush or recessed head-side surface.

Potential engineering advantages include:

• Reduced head projection

• Improved clearance for adjacent components

• Reduced interference with moving or sliding assemblies

• A more integrated surface profile

• Suitability for selected flush-head structural connections

These advantages depend on the actual installed geometry.

A countersunk head does not automatically provide greater joint strength than a protruding head.

Engineering Solution 2 — Countersink Angle and Head Compatibility

Countersunk lockbolts must be matched to the correct countersink geometry.

Important parameters include:

• Included head angle

• Head diameter

• Head height

• Countersink diameter

• Countersink depth

• Hole diameter

• Material thickness

• Head seating contact

Different fastener systems may use different countersunk angles.

A 90-degree countersunk head exists in certain industrial lockbolt systems, but this does not establish the angle of JUXIN JX-D-L-ST.

The correct angle must be taken from the approved drawing.

An incorrect countersink angle can cause poor head seating, localized contact stress or unacceptable head projection.

Engineering Solution 3 — Flush Head Installation

A flush-head connection requires more than selecting a countersunk fastener.

The connected component must have sufficient thickness and suitable geometry to accommodate the head.

Engineers should verify:

• Available material thickness

• Required countersink depth

• Residual material beneath the countersink

• Hole tolerance

• Head seating

• Installed head projection

• Joint load path

If the countersink is too shallow, the pin head may remain proud of the surface.

If the countersink is too deep, the head may sit below the surface or create an unacceptable joint condition.

The final head position should be included in the engineering acceptance criteria.

Engineering Solution 4 — Countersunk vs. Protruding Head Steel Lockbolts

A countersunk head should be selected for a genuine assembly requirement, not simply because it looks more streamlined.

Engineering Solution 5 — Steel Pin and Locking Collar Construction

A conventional two-piece lockbolt consists of a pin and a compatible collar.

Steel Countersunk Pin

The pin may incorporate:

• Countersunk manufactured head

• Load-bearing shank

• Grip section

• Locking grooves

• Installation gripping section

• Breakneck or alternative installation feature

Steel Locking Collar

The collar is installed on the opposite side of the assembly.

During installation, the collar is swaged into the pin grooves to form a permanent mechanical connection.

The collar must match the pin's geometry, material and installation requirements.

Pins and collars from different systems should not be assumed interchangeable.

Engineering Solution 6 — Ring-Groove Mechanical Locking

The ring-groove profile provides the mechanical interface between the pin and collar.

During installation, the tool applies the specified pulling and swaging forces.

The collar is plastically deformed into the locking grooves, producing mechanical engagement between the two components.

Important parameters include:

• Groove diameter

• Groove profile

• Groove spacing

• Collar dimensions

• Collar material

• Pin material

• Swaging force

• Installed collar geometry

Reliable performance requires a compatible pin, collar and installation tool.

Engineering Solution 7 — Steel Material Selection

The original product information identifies steel for the pin and locking component.

It also mentions traditional material descriptions corresponding to 35 steel and 10 steel.

However, these grades have not been confirmed against current product drawings or material certificates.

Engineering specifications should establish:

• Pin steel grade

• Collar steel grade

• Material condition

• Heat treatment, where applicable

• Hardness requirements

• Mechanical properties

• Surface finish

• Corrosion protection

• Traceability

The pin and collar may require different mechanical properties because they perform different functions.

No specific strength class is claimed without verified data.

Engineering Solution 8 — Countersunk Head Load Distribution

Countersunk head geometry changes the way load is transferred into the joined component.

Head-side bearing depends on:

• Head angle

• Head diameter

• Countersink quality

• Material thickness

• Mating material strength

• Applied tensile load

• Joint geometry

Potential failure mechanisms include head pull-through, local deformation and cracking around the countersink.

A countersunk connection must be evaluated for the actual joint materials and loads.

Engineering Solution 9 — Shear Strength

Shear performance depends on the load-bearing section of the pin and the complete joint geometry.

Important parameters include:

• Pin diameter

• Steel grade

• Pin geometry

• Shear-plane location

• Hole diameter

• Joint thickness

• Fastener spacing

• Edge distance

The countersunk head should not be assumed to increase the pin's shear strength.

No numerical shear capacity is claimed without verified product data.

Engineering Solution 10 — Tensile Strength

Tensile performance depends on the pin, collar and connected components.

Potential failure modes include:

• Pin fracture

• Collar deformation

• Collar disengagement

• Countersunk head pull-through

• Local panel deformation

• Joint material failure

The tensile capacity of a countersunk lockbolt connection must be verified for the complete fastening system.

Engineering Solution 11 — Clamp Force and Joint Integrity

During installation, the tool draws the joint together and swages the collar into the locking grooves.

The resulting clamp depends on:

• Pin geometry

• Collar design

• Material properties

• Grip range

• Joint thickness

• Surface condition

• Tooling

• Installation force

A specific clamp value cannot be inferred from the term high-strength.

Verified installation and performance data are required.

Engineering Solution 12 — Vibration Resistance

Properly engineered lockbolt systems may provide useful resistance to loosening in vibration-exposed assemblies.

However, performance depends on the complete joint.

Engineers should evaluate:

• Joint stiffness

• Collar engagement

• Clamp retention

• Hole fit

• Fatigue

• Fastener spacing

• Material compatibility

• Installation quality

The actual JUXIN configuration requires validation before use in demanding dynamic applications.

Engineering Solution 13 — Fatigue and Cyclic Loading

Countersunk connections require particular attention to stress distribution around the head and hole.

Fatigue performance may be influenced by:

• Countersink geometry

• Surface finish

• Hole quality

• Pin diameter

• Steel grade

• Joint stiffness

• Cyclic load spectrum

• Corrosion

Critical assemblies should undergo appropriate engineering analysis and representative testing.

Engineering Solution 14 — Grip Range and Pin Length

The correct grip range must accommodate the complete joined material stack-up.

Engineers should verify:

• Minimum grip

• Maximum grip

• Pin length

• Collar engagement

• Locking groove position

• Tooling clearance

• Installed pin projection

Incorrect grip selection may prevent proper collar swaging or acceptable joint formation.

Engineering Solution 15 — Hole Preparation and Countersinking

Hole preparation is especially important for flush-head lockbolt installations.

Recommended engineering checks include:

• Hole diameter

• Hole alignment

• Countersink angle

• Countersink depth

• Countersink concentricity

• Burr removal

• Surface condition

• Joint gap

• Edge distance

Countersinking may remove material from the connected component.

The remaining material thickness must be adequate for the intended joint design.

Engineering Solution 16 — Break-Pintail and Pintail-Less Systems

Ring-groove lockbolts are available in different installation configurations.

Break-Pintail Designs

Certain systems include a pulling section that breaks at a designed location after collar swaging.

Pintail-Less Designs

Other systems complete installation without a conventional break-off pintail.

Huck BobTail is a proprietary example of a pintail-less lockbolt system.

The actual JUXIN countersunk steel lockbolt configuration must be verified before assigning either installation method.

Huck Magna-Grip and Huck BobTail are proprietary systems and should not be used to imply product equivalence.

Engineering Solution 17 — Installation Tooling

Countersunk steel locking-collar rivets require compatible installation equipment.

Tool selection should consider:

• Pin diameter

• Collar diameter

• Groove geometry

• Pulling force

• Swaging force

• Tool stroke

• Nose assembly

• Working clearance

• Installation access

• Production cycle time

• Tool maintenance

The tool must be compatible with the selected pin-and-collar system.

A conventional blind-rivet tool should not be assumed suitable.

Typical Installation Procedure

1. Confirm the approved pin and collar part numbers.

2. Verify the steel material specifications.

3. Check the joint stack-up and grip range.

4. Prepare the mounting hole.

5. Machine the countersink to the approved angle and depth.

6. Inspect the countersink for burrs and damage.

7. Insert the countersunk pin through the assembly.

8. Verify that the head seats correctly.

9. Position the compatible collar on the opposite side.

10. Engage the approved installation tool.

11. Activate the tool according to the specified procedure.

12. Complete the collar swaging operation.

13. Complete the pintail break if required by the selected design.

14. Release the tool.

15. Inspect the installed collar and pin.

16. Verify the countersunk head position and joint condition.

Pintail-less systems must follow their approved installation procedures.

Engineering Solution 18 — Production Quality Control

Production managers and manufacturing engineers should establish inspection criteria for both the fastener and the prepared joint.

Important inspection items include:

• Pin part number

• Collar part number

• Material verification

• Head angle

• Head diameter

• Hole diameter

• Countersink depth

• Countersink concentricity

• Grip range

• Collar orientation

• Tool identification

• Swage completion

• Installed collar geometry

• Pin projection

• Head flushness

• Joint gap

• Surface finish

• Traceability

Where required, production trials should confirm the installation process before high-volume manufacturing.

Engineering Solution 19 — Corrosion Protection

Steel lockbolts may require protective coatings depending on the service environment.

Important considerations include:

• Steel grade

• Coating type

• Coating thickness

• Corrosion exposure

• Coating damage during installation

• Contact with dissimilar metals

• Hydrogen embrittlement risk where applicable

• Surface condition inside the countersink

The original product information does not establish a specific coating or salt spray rating.

Corrosion performance must be verified against the actual approved specification.

Engineering Solution 20 — Metric and Inch Size References

Common industrial lockbolt diameter references include:

These are general dimensional references, not confirmed available sizes for the JUXIN countersunk steel lockbolt product.

Actual pin diameter, head angle, countersink geometry, grip range, collar compatibility and installation tooling must be verified before substituting metric and inch-designated systems.

Industrial Applications and OEM Engineering Solutions

Countersunk steel locking-collar rivets may be considered where a permanent mechanically locked joint and a reduced head-side projection are required.

The following applications are potential engineering uses, not product-specific certifications or approvals.

1. Commercial Vehicle Manufacturing

Commercial vehicle assemblies may require flush-head fastening where protruding fastener heads would interfere with adjacent components.

Joint strength, fatigue and vibration requirements must be evaluated.

2. Trailer Manufacturing

Trailer frames, brackets and selected metal assemblies may use countersunk lockbolts where the approved design requires head-side clearance.

3. Heavy Equipment

Construction and mining equipment may incorporate steel components requiring permanent mechanical fastening.

Countersunk designs may be considered where surface clearance is important.

4. Agricultural Machinery

Agricultural equipment may include steel brackets, frames and structural assemblies where a recessed fastener head is desirable.

5. Rail Equipment

Rail equipment may use countersunk lockbolts in approved applications.

Fatigue, vibration, traceability and project-specific requirements must be reviewed.

6. Industrial Machinery Frames

Industrial machinery may require flush-head connections in selected frames, brackets and support structures.

7. Material Handling Equipment

Material handling equipment may incorporate assemblies where protruding fastener heads could interfere with moving components or material flow.

8. Conveyor Systems

Conveyor equipment may require low-projection fastening in selected structural or protective assemblies.

The joint must be evaluated for loading and operational clearance.

9. Industrial Steel Fabrication

Steel fabricators may specify countersunk lockbolts for permanent metal connections requiring a flush-head profile.

10. Modular Equipment

Modular structures and industrial equipment frames may use countersunk fastening where assembly clearances are restricted.

11. Power Distribution Equipment

Power distribution equipment may incorporate steel support frames and auxiliary assemblies.

Mechanical fastening and electrical bonding requirements must be evaluated separately.

12. Energy Storage Equipment

Energy storage infrastructure may use steel frames and equipment supports.

Countersunk lockbolts may be considered for suitable mechanical connections.

13. AI Data Center Infrastructure

Large data center installations may contain mechanical equipment frames, supports and auxiliary structures requiring controlled permanent fastening.

14. Industrial Enclosures

Heavy-duty enclosures may use countersunk fasteners in suitable frame or bracket connections where head projection must be minimized.

15. HVAC Equipment

Industrial HVAC systems may include steel frames, support brackets and protective structures.

Countersunk lockbolts may be considered where vibration and clearance requirements are appropriate.

16. Telecommunications Equipment

Telecommunications infrastructure may use steel supports and equipment frames requiring permanent fastening and controlled head projection.

17. Renewable Energy Equipment

Renewable energy installations may incorporate structural frames and mechanical supports where approved countersunk fastening is suitable.

18. Specialized Transport Equipment

Specialized transport equipment may require flush-head fastening in selected structural metal assemblies.

19. Industrial Automation Equipment

Automation machinery may contain moving mechanisms and equipment frames where head-side clearance is important.

20. Custom OEM Metal Fabrication

OEM manufacturers may specify countersunk steel locking-collar rivets according to approved drawings, material requirements, mechanical performance and annual production volumes.

Engineering Selection Matrix

Common Installation Problems and Corrective Checks

International Standards and Technical Qualification

Countersunk steel lockbolts may be specified using manufacturer technical specifications, customer-approved engineering drawings and applicable industry standards.

Different lockbolt systems may use different:

• Countersunk head angles

• Head diameters

• Groove profiles

• Collar configurations

• Steel grades

• Grip ranges

• Installation procedures

• Mechanical performance requirements

Where ISO, DIN, EN, ASTM, SAE, BS or customer-specific requirements apply, conformity must be verified against the actual product.

Huck Magna-Grip, Huck C6L, Huck C50L and Huck BobTail are proprietary fastening systems.

Similar appearance or generic countersunk lockbolt terminology does not establish equivalence or interchangeability.

No unverified certification, strength class or proprietary system equivalence is claimed.

OEM Procurement and Supplier Development

For purchasing managers, supply chain managers, production managers and engineers, countersunk steel lockbolts should be specified as complete, compatible fastening systems.

A technical RFQ should include:

• Countersunk pin drawing

• Locking collar drawing

• Pin steel grade

• Collar steel grade

• Head angle

• Head diameter

• Countersink dimensions

• Pin diameter and length

• Groove configuration

• Grip range

• Mounting-hole diameter

• Required shear strength

• Required tensile strength

• Clamp and fatigue requirements

• Corrosion protection

• Installation tooling

• Inspection criteria

• Expected order volume

• Annual demand forecast

Purchasing teams should confirm whether the quotation includes pins only, collars only or complete matched assemblies.

Total installed cost should consider fastener cost, countersinking operations, tooling, installation time, inspection and maintenance.

Frequently Asked Questions

What are countersunk steel locking-collar rivets?

They are two-piece mechanical fasteners consisting of a countersunk steel pin and a compatible locking collar that is swaged into the pin grooves.

Are countersunk locking-collar rivets also called flush head lockbolts?

Yes. Flush head lockbolts is a commonly used market description for suitable countersunk lockbolt configurations.

Are countersunk lockbolts the same as blind rivets?

No. Typical two-piece lockbolts require access to both sides of the joint, while conventional blind rivets are installed from one side.

What is the countersunk head angle?

The actual angle must be confirmed from the approved JUXIN product drawing. It should not be assumed to be 82, 90 or 100 degrees.

Will the head always sit flush?

No. A flush result depends on correct head geometry, countersink preparation, material thickness and installation quality.

Are countersunk lockbolts stronger than protruding-head lockbolts?

Not necessarily. Mechanical performance depends on the complete fastener and joint design.

Can these lockbolts be used in thin sheet metal?

Only where the material thickness and countersink geometry provide an acceptable engineered joint.

Do all steel lockbolts break off a pintail?

No. Break-pintail and pintail-less designs use different installation mechanisms.

Are these products equivalent to Huck Magna-Grip or C50L?

Equivalence has not been established. Any proposed substitution requires engineering verification.

Can JUXIN review custom countersunk steel lockbolt drawings?

Customers may submit drawings, material specifications, countersink geometry, mechanical requirements and annual demand for technical review and quotation.

Request a Countersunk Steel Locking-Collar Rivet OEM Quotation

JUXIN FASTENERS supplies industrial fastening solutions for OEM manufacturing, metal fabrication, commercial vehicle production and machinery assemblies.

Please provide the following information for technical review:

• Material family reference: JX-D-L-ST

• 2D engineering drawing or 3D CAD model

• Countersunk head angle

• Head diameter and height

• Countersink diameter and depth

• Pin steel grade

• Collar steel grade

• Pin diameter and length

• Ring-groove profile

• Grip range

• Mounting-hole diameter and tolerance

• Required shear strength

• Required tensile strength

• Clamp and fatigue requirements

• Break-pintail or pintail-less configuration

• Installation tooling and nose assembly

• Surface finish and corrosion requirements

• Inspection and traceability requirements

• Pin and collar supply quantities

• Expected annual demand

• Packaging specifications

• Target delivery schedule

Email: info@juxinfasteners.com

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

JUXIN FASTENERS — Countersunk Steel Locking-Collar Rivets and Flush Head Lockbolts for Global OEM Manufacturing.

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.