18 May 2016
Flexnuts are used in combination with Superbolt tensioners and are designed to flex out at the bottom and flex in toward the top of the nut. This distributes the bolt load along many threads, adds elasticity, and prevents stress concentrations in the first few threads.
For through hole applications we have developed the Superbolt flexnut, which is a reactive nut that is able to flex elastically. Putting a Flexnut gives the same advantages as the MJT on the reactive side. Under load they flex at the bottom and at the top. This helps relieve stress concentrations and increases the fatigue life of the bolt. Since flexnuts are reactive nuts to be used opposite our tensioners, they are never torqued directly to achieve preload.