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How HuckBolts® Work

Clamp Force or Pre–Load: In the initial stages of the installation process, the 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 bolt. The bolt 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 bolt, generating a clamp force over the joint.

Shear strength of HuckBolts vary according to the material strength and 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 HuckBolts is dependent on the shear resistance of the collar material and the number of grooves it fills.

LockBolt Installation Sequence
  1. Pin inserted into prepared hole -- collar spun into pin
  2. Tool is applied to annular pull grooves and activated
    • Nose assembly draws pin into the tool 
    • The swaging anvil presses on collar
    • Draws up sheet gap
  3. Anvil begins to swage collar into lockgrooves
    • Collar and pin elongate, developing precise clamp
  4. Tool ejects fastener and releases puller -- installation complete

HuckBolts Range


BobTail Removal

The cutter tool, part of the BobTail installation tooling system, makes removing the Huck BobTail quick and easy. If the BobTail pull grooves are left intact, the installation tool itself can also be used as a removal tool – just slide it down the anvil to break off the collar.


How Structural Blind Fasteners Work

The shear strength of structural blind fasteners is generated by the combined resistance against failure of the bolt and sleeve. This takes place along the joint’s shear line between fastened plates.

The tensile strength of structural blind fasteners differs to that of HuckBolts, as they form a blind side positive lock either by bulbing or expanding of the sleeve. The sleeve, assisted by the permanently secured bolt, therefore resists failure along its center line.

1. Bulbing
The sleeve of the fastener is compressed, causing it to fold outwards to form a bulb. This form itself tightly against the joint material. Once the bolt is permanently locked into place the pintail will break off, completing the installation.

2. Expanding
Pulling on the pintail causes the head of the bolt to draw into the sleeve. This expansion causes a foot print to form against the joint material.

Note: The pre-load of blind rivets is generally not published, as it varies widely depending on the application.

Blind Fastener Installation Sequence
  1. Bolt placed into prepared hole
    • Tool is placed over the fastener pintail
  2. Tool activated
    • Deforming of blind side begins
  3. Joint tightened
    • Internal locking mechanism formed
  4. Pintail breaks
    • Installation complete

Blind Fasteners Range