**5.6 Lock nut**

By "doubling nut" this method uses two nuts applied to the threaded fastener in order to provide a secondary force or lock to the initial nut. This does not significantly increase clamp load and may add additional stress to the threaded fastener.

**121**

**Figure 4.**

*Object on an inclined plane.*

*Liquid Thread Locking Solution for Machinery Assembly Industry*

and doubles the cost of the locking device (see **Figure 3**) [1].

of tooth flanged bolt is required, too (see **Figure 3**) [1].

**6. Shortcomings of mechanical locking devices**

are more costly than liquid thread locking adhesive.

**6.1 How does bolt and nut loosen?**

most expensive locking mechanism in the market (see **Figure 3**) [1].

This does not provide a seal and is prone to coming loose under vibrational loads

The "tooth" on the bolt grips and digs into the surface of the material or metal that is being assembled. This method also allows an initial loss of bolt tension as the tooth bolt rotates and digs into the bearing surface and stops. The tooth may dig into coated metals or damage the coating finish. This device does not seal the assembly. Under the vibration and impact, the bolt rotates until the tooth digs into the metal surface and finally grips the metal to prevent a further loosening; however, until then, pretty much amount of bolt tension is already lost, and a high cost

A pair of wedge-locking washers with radial teeth on opposite surfaces grip the surface and are under the bolt head. It may damage coated or plated surfaces. It does not seal the joint and requires more torque to obtain target clamp load. This is the

As described on the above chapter, conventional mechanical locking devices have those shortcomings such as they lose under vibration, thermal expansion, and/ or improper torque, and they do not seal threads, and they require extensive inventory of several shapes and sizes, and they are prone to rust and surface damage, and they have a wide tension scatter, and their torque is not well augmented, and they

Threaded fasteners were designed to be removed anytime. The problem is that it loosens unintentionally. Thread is a rolled cone and unrolled thread is an inclined plane. As shown in **Figure 4**, "F sin a" of the induced load assists the loosening. When an object is in an equilibrium state between gravity and friction on an inclined surface, and then, if there is a sideway transverse impact or vibration applied to the

*DOI: http://dx.doi.org/10.5772/intechopen.85090*

**5.7 Tooth flanged bolt**

**5.8 Wedge-locking washers**

This does not provide a seal and is prone to coming loose under vibrational loads and doubles the cost of the locking device (see **Figure 3**) [1].
