Lock nut, also referred to as a locknut, locking nut, self-locking nut, prevailing torque nut, stiff nut or elastic stop nut is a nut that resists loosening vibrations and torque. A number of different types and designs have been developed over the years for use in a wide range of applications. They all provide resistance to loosening forces with using lock washers which improve the manufacturing process.
They fall into two broad groups.
- PREVAILING TORQUE – an intrinsic feature of the lock nut produces friction between threads of mated components thereby increasing the resistance to loosening forces. The two main categories of prevailing torque type nuts include: all metal and nylon insert lock nuts.
- SURFACE-BEARING – a free spinning nut that requires tightening against a bearing surface in order for the locking mechanism to function. Two common surface bearing type lock nuts include: serrated flange and KEPS (K-Lock)
A nylock nut, also referred to as a nylon-insert lock nut, polymer-insert lock nut, or elastic stop nut, is a kind of locknut with a nylon collar insert that resists turning.
The plastic insert is placed at the end of the nut, with an inner diameter (ID) slightly smaller than the major diameter of the screw. The insert deforms elastically over the threads of the screw, without having threads in turn cut into it. The nylon insert locks the nut by friction against the screw under the applied radial compressive force. Nyloc nuts retain their locking ability up to 250 °F (121 °C).
Available as per DIN 982 – Full Nylock Nuts and DIN 985 Half Nylock Nuts
Material Grades: Steel Zinc Coated, Stainless Steel AISI 304 and AISI 316
Flanged NyLock Nuts
These nuts are created to a standard of DIN 6926. Flange Nyloc (nylon insert) Nuts are torque prevailing nuts which use plastic/nylon inserts that are located towards the top of the nut – which reduce its inner diameter – therefore deforming the insert over the mating thread and capturing the bolt or screw and providing a locking feature.
Metal Lock Nuts
All Metal lock nuts work on the principle of a slight deformation in the nut. Locking is achieved by deformation of the last thread. This is a top locking style nut.
Are also known as half-thickness nut or a split nut; these are used as a locknut or jam nut. Used in conjunction with a standard nut.
- Made as per DIN 439 and ISO 4035
- Materials: Steel and Stainless Steel AISI-304 and AISI-316
- Now also available in Metric Fine Threads and Left Hand Threads
consists of a nut in a spring steel cage which wraps around the nut. The cage has two wings that when compressed allow the cage to be inserted into the square holes, for example, in the mounting rails of equipment racks. When the wings are released, they hold the nut in position behind the hole. Cage nuts conforming to this description were patented in 1952 and 1953.This design requires insertion tools to install the cage nut into the hole. Newer designs featuring a squeeze-and-release tab allow for tool-less installation
Flange Nuts DIN 6923
Serrated flange nut or Flange lock nut has a flange shape above the hexagonal body surface which increases its bearing surface allowing them to be used with irregular oversized holes. The ﬂange offers protection for the bolted component where the driving tool may otherwise scratch it’s surface. The ﬂange also lessens the need to use a washer.
Keps nut, (also called a k-lock nut or washer nut), is a nut with an attached, free-spinning washer.
It is used to make assembly more convenient.