**5.7 Tooth flanged bolt**

*Adhesives and Adhesive Joints in Industry Applications*

**5.3 Nut with nylon insert**

*Conventional thread locking fasteners.*

**Figure 3.**

**5.4 Tab washer**

**5.5 Castellated nut**

**5.6 Lock nut**

is required, too (see **Figure 3**) [1].

nylon insert friction, too (see **Figure 3**) [1].

loosening. This also does not seal, can damage the surface of softer or coated metals, and is not reusable, and additional cost of star washer is required (see **Figure 3**) [1].

Nylon or "plastic" deforms into void in the thread. This method allows an initial loosening, and the bolt tension is already reduced, but it can prevent a further loosening, and it is also recommended to be replaced after each disassembly with new nut in order to maintain optimal performance as when reused it loses a significant amount of its ability to fill the voids. Cost of nylon insert must be considered, too. Nylon also insulates the heat developed from thread friction making the assembly more susceptible to galling during installation. It is difficult to tighten because of

Tab washer mechanically overlaps the edge of a surface or flange. It acts as a normal washer, spreading the clamp load over a wide area. This method allows an initial loosening of bolt tension due to the empty space between threads. But due to its structure, it prevents a further loosening, and it does not seal or technically lock the assembly, and additional cost of tab washer is required (see **Figure 3**) [1].

Castellated nut uses tension to mechanically "grip" the bolt or threads. Cotter pin is also sometimes used in conjunction with this device to prevent nut from falling off. However, cotter pin will not prevent loss of clamp load after initial loosening. It fails when vibrational load or impact causes the fastener to lose clamp load. This device does not seal the threaded assembly, and the high cost of castellated 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.

**120**

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