Expansion screws / expansion bolts - special screws for special applications

Applications with varying operating forces and large temperature variations require fasteners with high durability. Expansion screws / expansion bolts are characterized by a reduced shank diameter compared to full shank or fully threaded screws. Where rigid screw connections fail or loosen, the elasticity of expansion screws / expansion bolts results in a greater elastic change in length with the same preload force, thus ensuring a secure screw connection.

Mouse_Scroll_Icon
Mouse_Scroll_Icon

The principle of expansion screw / expansion bolt / special screw

In contrast to full shank or fully threaded screws, expansion screws / expansion bolts allow axial expansion in the shank area under strain due to their special shank. This leads to increased long-term stability and effectively reduces the risk of the connection settling. When installed, the connection behaves like a pre-tensioned tension spring.

In order to achieve the best possible elasticity, the shank diameter should be smaller than the core diameter of the thread and the shank should be longer.  Due to these geometric modifications and the resulting stability, additional resources such as screw locking can be dispensed with.

Expansion screws / expansion bolts / special screws – benefits overview

 

  • High load-bearing capacity and durability under changing loads
  • Secure and stable connection thanks to controlled and equal preload
  • Prevents the connection from settling
  • No additional screw locking required
Expansion screw_technical presentation - Expansion screws

References:

Expansion screws, expansion bolts and special screws