What subsequent maintenance is required after HARDLOCK Nuts are fastened (such as further tightening)?
After completing the initial clamping, it is recommended that the nut assembly be given an additional turn to ensure a smooth engagement of the threads.
In the case that additional tightening is not possible, please take into account the anticipated decrease in the bolt’s axial tension(10%-20%) by applying additional torque when performing the initial clamping.
What special care should be taken when removing HARDLOCK Nuts?
First, apply lubricant to the bolt and the nuts. Then remove the concave nut first, followed by the convex nut. Do not attempt to remove both nuts together as this will cause the nuts seize up.
Are there any cautions to be observed when reusing HARDLOCK Nuts?
Do not use a HARDLOCK Nut if when tightening the concave nut until it is pressed against the convex nut (in general, a gap of one screw pitch is needed between the concave and convex portions), no gap whatsoever is found between two nuts, as this means that the wedge effect will not function. In such a case, please contact HARDLOCK Industry directly. (The class of bolt used can also be a problem.)
What factors can contribute to looseness when HARDLOCK Nuts are used?
There are two factors with respect to looseness, namely a relative rotation of the nuts against the counterpart bolt and a decrease in bolt-axial tension.
Loosening of the nuts due to rotation is limited to the following cases in which the wedge-effect does not function.
Where the upper concave nut is not tightened with the specified torque
Where after repeated use, the upper nut is deformed and does not function
Where the nuts have been incorrectly installed
Next, potential factors contributing to a decrease in bolt- axial tension include the following.
Where the lower convex nut is not sufficiently tightened
Where axial tension between the nut and the corresponding bolt decreases after a considerable lapse of time following the initial clamping.
Where the clamped part becomes deformed over time
Where he clamped part becomes embedded causing the nuts loosen
Where dissimilar products made of metals with different coefficients of linear expansion are fastened in conditions subject to significant temperature swings.
Apart from the above, there are many other conceivable factors that may contribute to looseness, but these have absolutely no relation to the construction of the HARDLOCK Nut.
