These washers are also known as vibration-proof washers. These washers possess a unique feature or serrations on the internal surfaces. When final flattening of the safety washer occurs with tightening of the screw, these serrations bite into the mating faces, thus preventing loosening of the screw, nut, bolt, etc due to vibration. Serrated Washers are ready to fit the washer to sustain preload and avoid loosening. Serrated washers increase the friction between the nut or bolt head and the mating surface. These washers can do this by gripping into the mating surfaces. Serrated washers are installed between the bolthead or nut and the mating surface. The bolted joint is tightened in the same way as an unsecured bolt. If the bolted joint experiences a loss of tension, the washer is no longer effective and needs to be replaced. Single part serrated washers can damage coated or painted surfaces because they possess the tendency to rotate with a fastener. It risks the damaging surface, cracking the coating or paint, and causing corrosion.
Due to the above-mentioned features of serrated washers, these are also used in cable gland accessories. Serrated Washers fitted internally to the equipment and before a locknut act as an anti-vibration device to prevent the cable gland or other cable entry device and locknut. These are particularly required in situations where vibrating heavy machinery such as mud, shakers, vibrating machines or pump, drilling equipment. Serrated Washers are Disc Springs with Trapezoidal Cross Section on both sides for gripping. IIS serrated safety washers are ready to fit washers to sustain preload and avoid loosening. As the bolt is tightened the serrations crunch into the mating faces and prevent the screw from loosening up due to vibration. Also, the disc shape holds the necessary tension.
The advantages of using serrated washers:
High vibration resistance due to positive rib contact.
Excellent pre-tensioning.
No splitting or cracking occurs during tightening due to correct dimension selection.
No chances of bending because of the concentric force of serrated washers.
Extensive application and flexibility.
ASTM, IS, ISO, DIN, ANSI, ASME, and all international standards.