Metal Insert Lock Flange Nuts

Flange lock nuts are also known as flange style automation lock nuts, prevailing torque flange nuts, and deformed thread flange lock nuts. Flange lock nuts are one-piece, all-metal prevailing torque hex flange nuts. Flange lock nut size refers to its nominal thread diameter. Typically, sizes range from about 1/4" to 1". Size is specified in inches, usually fractional rather than decimal. Being all-metal, they are not subject to the temperature and chemical limitations of non-metallic (such as nylon) insert type lock nuts. The protruding circular flange increases the nut's bearing surface allowing them to be used with irregular and oversized holes.
The advantage is that disassembly is unlikely even if preload diminishes completely because of the remaining rotational resistance.
However, their "locking" feature does resist loosening without the nuts being seated, which allows them to be used as stop nuts or spacers for rotating or other components. Despite the fact they are called "lock nuts," flange lock nuts are not permanently locked in place so they can be adjusted or removed after installation.
Flange lock nuts are reusable but only for a limited number of times because the prevailing torque declines each time the nut is used.
The main usage of these nuts is in commercial and industrial applications include lawn and garden equipment and truck manufacturing.