Thin nuts are basically the same as standard thick nuts except for their hex height. In applications with limited installation space, thinner nuts are used to fit the available space, which is the most common use for thin nuts. However, thin nuts are sometimes also specified even where space is not restricted. To understand why thin nuts are still used despite their lower torque strength compared with standard nuts, we first need to understand the preload and fatigue performance characteristics of nuts of different thicknesses.
In practice, thin nuts are not usually used alone. They are paired with a standard nut to provide thread locking. When using a thin nut together with a standard nut, the correct installation procedure must be followed: the thin nut should be installed and tightened first, followed by the standard nut. Only with the correct order can reliable locking performance be achieved.
In actual assembly, workers often ignore this order and install them incorrectly, resulting in locking failure. For this reason, many companies simply use two standard nuts jammed together. Although this increases material cost, it effectively avoids installation errors.
Some companies rely only on spring washers for locking to save cost, but this method is not reliable. Extensive tests show that spring washers have limited locking effect and quickly lose their function under equipment vibration. Therefore, the combination of a thin nut and a standard nut is currently one of the most effective and convenient mechanical locking methods.
During installation, the two nuts must be tightened separately. Never install the standard nut immediately without fully tightening the thin nut first, as this will not create effective locking stress. If the thin nut is not tight, even if the standard nut is tightened very firmly, no anti-loosening effect will be achieved. When loosening, both nuts will turn together easily.
The correct method is: first tighten the thin nut completely, then tighten the standard nut to create a jamming effect. When removing, the outer standard nut must be loosened first with a wrench before the thin nut can be turned, ensuring stable and reliable anti-loosening performance.
