The best and secure fastening solution for vibration environments

Why hard lock?

Amongst all the available fasteners or locking nuts, the hard lock nut has proved itself to resist longer vibrations. It is a reusable product that maintains the same level of locking ability even after many uses. It has become the first choice for mechanical works in some of the top countries like Japan, the United States of America, United Kingdom, and Europe.

What makes the fasteners become loose?

The main reason behind fasteners becoming loose is the presence of play between the bolt and nut. And if you completely eliminate that play, you will achieve the ideal looseness prevention mechanism.

After a lot of research, the hard lock has come up with a fastener that has solved this long existing problem. It works on a wedge principle which creates an unmatched and strong self-locking system.

How it works:

In the hard lock solution, two nuts, one that is convex and one that is concave play the roles of both hammer and wedge respectively. The sliding part of the convex top of lower nut has got a small eccentricity which acts as a wedge. When you have tightened the concave upper nut, the effect produced is similar to that produced by a hammer driving in a wedge. Moreover, it is far more convenient to use a screw as it makes easier to force the wedge into place.

Once the lower nut gets tightened, install and tighten the upper nut by hand. A gap will be created which is known as the tightening margin. It is used to provide a self-locking effect.

During installation, installing the concave nut first and then tightening the convex nut gives the same self-locking effect.

Tightening the upper nut by wrench generates a torque which allows you to feel the self-locking effect by hand. You can use this effect to set the torque value as required. This eliminates any kind of existing gap, allowing the nut to be securely tightened.

The reusability of the nut depends on the prevailing environmental conditions, but as long as the material is not excessively deformed or deteriorated its self –tightening is not affected.


Hard lock nuts are ideal for almost all fields of engineering. Some of the major fields are aircraft, automotive and construction applications.

They come in a variety of materials with a range of surface treatments which helps it to meet the needs of varying applications. Some of the commonly used shapes are standard ones, semi-thin, thin and round, and also customizable shapes depending upon your requirement.

The hard lock nuts have outlasted nylon nuts, nuts with tongue washers, double nuts, and many other specialty nuts.

It has been able to retain their hold longer than competitor versions in a series of Junker Horizontal Screw Looseness test.


A hard lock is a simple versatile solution which has enhanced the fastening integrity. Now with the minimal cost, you can protect your expensive machinery from the different effects of vibration. Moreover, it also reduces the time-consuming checking and inspection of loose fastenings. There is no need for replacement of non-reusable locking nuts.

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