by Subhadeep Datta Subhadeep Datta

The Complete Guide to Blind Sheet Metal Fasteners and Their Benefits

What are Blind Sheet Metal Fasteners?

Blind fasteners are a type of metal fastener. They are also called “blind rivets” or “blind bolts”. These blind metal sheet fasteners are used to join two overlapping sheets of metal.

Huck® Magna-Bulb®

Huck Magna Bulb® blind sheet metal fastener perfect for lower strength or thin sheet joint materials. It gives high Mechanical Performance (Best in class). Very high shear strength and high tensile strength.

  • Seizes the joint with clamp
  • Consists Magna Bulb® – Blind fastener of two pieces, called mandrel and sleeve
    • Mandrel is heat treated, with rolled pull grooves
    • Mandrel contains shear ring to bulb sleeve
    • Sleeve material is softer than pin 
    • Sleeve is band annealed to facilitate formation of bulb
  • Installs with special tool
    • Pin lock retains pin
  • Pin breaks flush with head of sleeve

Preparation

  • Insert mandrel and sleeve into hole
  • Insert mandrel into nose assembly
  • Jaws ratchet over mandrel until insert contacts the sleeve

Installation

When trigger is engaged:

  • Jaws pull mandrel
  • Mandrel draws through sleeve, beginning to form bulb on backside
  • Bulb forms, providing bearing area
  • Shear ring breaks free and presses on catch grooves
  • Mandrel shoulder hits sleeve lock and forces material into pin lock pocket

Tool ejection

  • Jaws continue pulling
  • Mandrel breaks at breakneck
  • When trigger is released, nose assembly frees from sleeve

Use in applications that require:

  • High shear strength
  • High tensile strength
  • Consistent clamp (compared to other blind fasteners)
  • Loosening resistance in vibration situations
  • Broad blind side bearing surface
  • High pullout strength, esp. with mis-aligned, oversized or out of round holes
  • Pull through resistance on thin materials
  • Back side clearance
  • Flush pin break

Refer to current industries

  • General manufacturing
  • High vibration applications
    • Commercial truck body assembly
    • Seat track
    • Engine enclosures

Special features against blind fasteners for metal

Extra large blind side footprint: Ideal for lower strength or thin sheet joint materials


Structural fastener: It provides high tensile strength and very high shear strength 

Flush pinbreak: The blind side of fasteners are free from catching on clothes, skin or goods. No special tool required for checking the installation but it gives Quick and easy visual inspection


Internal pin locking mechanism: Secure within the rivet body and protected from corrosion


Headstyles: Protruding


Materials: Steel

A Unique Bulbing Fastener with High Shear Strength

Huck Magna-Bulb® is a unique, clamp-type blind fastener offering high shear strength in specific applications. Its bulbing action during installation spreads the load over more surface area. Post installation, this blind fastener supplies stronger, longer-lasting connection. Thus Magna Bulb® blind fastener offers superior blind side strength. 

This increased bearing area makes Magna-Bulb-blind fastener ideal for pullout resistance in thin materials, and oversized or misaligned holes. Positive, mechanical pin-retention ensures structural integrity no matter what the application.

Secure, Fast Installation

  1. Shear ring design promotes bulb formation and grip adjustment for flush break throughout the grip range
  2. The wide blind footprint (bulb) gives the fastener a broader bearing surface, spreading the load out for greater strength and high pull out resistance 
  3. Unique solid circle lock ensures maximum strength and resistance to vibration 
  4. Breaking flush throughout the entire grip range, the Magna-Bulb fastener eliminates costly cosmetic finish work. Simple visual inspection ensures that the fastener is installed correctly.

Installation Sequence

Application picture (where there is no access in blind side)

Tools for Magna Bulb® – Blind fasteners installation:

by Subhadeep Datta Subhadeep Datta

How Does A Huck Bolt Machine Work

Huck® Bobtail

The Next Step In Lockbolt Evolution

Designed to overcome inherent weaknesses with standard lockbolts, the BobTail has no pin-tail and as a result of this zero pin-break, no waste material to collect and dispose of or potential corrosion issues post-installation. The lightweight, low-noise, low-maintenance Huck tool, which can be used for both installing and removing fasteners, provides a smooth, shock-free, speedy installation sequence i.e. two seconds for a 16mm diameter fastener – twice as fast as any other large diameter lockbolt. As a result, no torque or impact is transferred to the operator.

Benefits of Using Bobtail®

  • Unmatched installation speed
  • High fatigue strength thread form
  • maintenance-free
  • consistent clamp
  • installation indicator on collar for visual inspection
  • low installation noise & no waste
  • easy to learn, shock-free installation
  • unique helical lock groove

Huck Bobtail® Next Step In Lockbolt Evolution

The Huck BobTail system includes Lock Bolts and installation tooling that will deliver you benefits beyond anything that Howmet Fastening Systems has produced before.

Cycle Installation Speed of fastener has to be seen to be believed with the 1/4 diameter BobTail fastener installing in less than 1 second. The 16mm diameter BobTail fastener installs in 2 seconds, up to twice as fast as any large diameter LockBolt on the market.

Combined with all the benefits of using a Huck LockBolt Permanent, mechanically locked fastener: Installation process automatically provides fastener values No torque or re-torque required Unlike conventional nuts and bolts, they will never loosen, even during extreme vibration Easy visual inspection ensures correct installation

How Bobtail Works

Clamp Force or Pre–Load:

In the initial stages of the installation process, the tool engages and pulls on the tail of the fastener. The joint is pulled together before the anvil portion of the nose assembly is forced down the collar. This progressively locks (swages) it into the grooves of the harder pin. The pin and swaged collar combine to form the installed fastener. The squeezing action reduces the diameter of the collar, increasing its length. This in turn stretches the pin, generating a clamping force over the joint. The shear strength of BobTail fasteners varies according to the material strength and minimum diameter of the fastener. By increasing the diameter or the grade of material, the shear strength of the fastener can be increased. The tensile strength of BobTail Huck bolt fasteners is dependent on the shear resistance of the collar material and the number of grooves it fills.

Installation sequence

  • Pin placed into the prepared hole
  • Collar placed over the pin
  • The tool is placed onto the annular pull grooves and activated
  • A puller in the nose assembly draws the pin into the tool
  • Pin head pulled against material
  • Anvil pushes collar against joint
  • Initial clamp generated
  • Tool swages collar, increasing clamp
  • Swaging of the collar into the pin lock grooves is complete, tool ejects the fastener and releases the puller, installation complete

Huck®, Camloc®, Marson®, Recoil® is a brand owned by Howmet Fastening Systems (erstwhile Arconic Fastening Systems) , a leading designer and manufacturer of high-performance, proprietary fasteners and fastener installation systems.

Macros Fastening Systems is proud to be the only authorized distributor of Huck® Fasteners – Huckbolts®, Blind rivets, Huck® tooling, Recoil® inserts & installation tooling, Camloc® latches and SNEP nuts in India

by Subhadeep Datta Subhadeep Datta

How to Install Huck Bolts Using a Huck Bolt Installation Tool


What Are Huck® Lockbolts?

A Lock Bolt is a two-piece fastener that consists of a hardened metal pin and a metal collar that swages into the grooves of the pin, forming a specific, measured clamp force to hold assembled parts.

The Huck® installation tool grips the pintail of a Lock Bolt and then pulls to close the gaps in the materials being joined. Inside the nose assembly, a hardened steel conical-shaped anvil is then forced down the collar to progressively squeeze, or swage, the collar material into the grooves. 

This direct metal-to-metal contact of the collar swaged into the grooves of the pin eliminates the loosening effects of transverse vibration.

  • Often installs in Under 2 Seconds
  • Consistent, High Clamp Force
  • Certified Maintenance-Free Joints
  • High Shear, Tensile, Pin Strength

Some of our best Huck® Lockbolts to provide strength to your machinery.

C6L ® The Original Vibration-Resistant Huck Bolt®

A result of Huck International innovation a half-century ago, the versatile C6L® Huck Bolt® remains the number one fastening system for applications that require a strong, vibration-resistant seal today.

C6L’s exclusive locking groove design ensures a permanent fit that resists loosening. That means it’s ideal for applications from general manufacturing to such high-vibration applications as HVAC, trailer and container assembly, rotary and rotating equipment, shopping carts, railroad, and transit cars, geodesic structures, and many others.

In addition to offering superior fastening performance, the C6L system reduces labor and installation costs, along with rework and warranty expenses. Using the C6L eliminates the need to hire certified welders or specially trained employees because workers can be instructed to install these foolproof fasteners in a matter of minutes. The C6L is simply stronger, easier to install, and more durable than welding, adhesives, or conventional threaded fastening systems. The C6L is available in Grade 2, Grade 5, and Grade 8.

Available Sizes: 3/16”, 1/4”, 5/16”, 3/8”

Materials: Steel, Aluminum, Stainless Steel

Head styles: Round, Truss, Flush, 98T

The C6L’s unique design virtually eliminates installation errors caused by operator or tool variables. The C6L ensures that once the collar swage is complete, the pintail breaks off and the fastener is tightly installed. No rework is required. You can count on consistent, highly-uniform clamp force with every C6L installation, time after time.

1 Wide bearing collar and head spread the load to ensure structural integrity.

2 Initial long length of fastener enables pull-out of large gaps.

3 Excellent gap pull-out and high retained clamp.

4 High-fatigue, annular lock groove form extends the life of your structure.

Huck® C50L® The Fastener That Has Defined Huck Bolts for More Than 50 years

The C50L® offers superior vibration resistance and overall durability for heavy-duty fastening jobs and is ideal for use within applications where consistent, uniform high clamp force is required. Testing has proven that C50L fasteners meet, or exceed the performance of torqued bolts in both shear and tensile strength, as well as fatigue life. For heavy-duty applications ranging from railcar to mining equipment manufacturing, the C50L delivers superior vibration resistance and overall durability.

Available Sizes: 1/2”, 5/8”, 3/4”, 7/8”, 1”, 1-1/8”, 1-3/8”

Materials: Steel, Aluminum

Head styles: Round, Truss, Large Truss, 90° Flush, Thread Head

Unlike threaded fasteners, the C50L HuckBolt® delivers consistent installation results. High costs of calibrating, maintaining, and replacing tools are eliminated. Also, installation does not require expensive, highly experienced workers.

1 Swaged-on collar forms a permanent, vibration-proof connection.

2 Initial long length of fastener enables pull-out of large gaps.

3 Consistent, repeatable pre-load

How Do Huck® Bolts Work?

Clamp Force or Pre-Load

In the initial stages of the installation process, the Huck® lock bolt tool engages and pulls on the pintail. The joint is pulled together before the conical-shaped cavity of the nose assembly is forced down the collar. This progressively locks (swages) it into the grooves of the harder pin. The pin and swaged collar combine to form the installed fastener. The squeezing action reduces the diameter of the collar, increasing its length. This in turn stretches the pin, generating a clamp force over the joint.

Shear strength

Varies according to the material strength and minimal diameter of the fastener. By increasing the diameter or the grade of material, the shear strength of the fastener can be increased.

Tensile strength

The tensile strength of Lock Bolts is dependent on the shear resistance of the collar material and the number of grooves it fills.

Lock Bolt Installation

Installing Huck® Bolts Using Huck Bolt Installation Tools.

  1. Before installation, you need to make sure that you have the right size of Huck® bolts for the process. You would want to go for one that has the right size and strength for your needs.

  1. Put the Huck® bolt in the hole prepared for it. Try to make sure that the bolt is the right fit for the application, or there are chances of lateral movement. This movement can weaken the joint over time.

  1. When you place the Huck® bolt in the cavity, the collar will be over the pinhead. When you use a Huck® lockbolt installation tool for the process, the reliable collar will form a durable connection that lasts for years.

  1. We have many different kinds of hydraulic machines that can help with your installation process. We have hydraulic and pneudraulic powered Huck® bolting machines that effectively help you install Huck® bolts in seconds. A few of our best products are the Swage forward Range and Huck® Range Force Battery Installation Tool.

  1. From the wide range of tools available, try to choose the perfect match for your needs. Put the machine’s nosepiece into the collar, over the pintail. Activate the Huck® bolt tooling.

  1. The activation process will put pressure on the collar and brings the pieces of the bolt together. It ensures a sturdy design that cannot become loose over time.

  1. Once the process is complete, the tool breaks from the pintail, and you can remove the machine.