Bolts should be tightened adequately or there are chances of serious consequences. If a failure happens then how can we judge in the very first instance that the bolt tightened had some manufacturing defects or any design flaw? The very first thing is whether the bolt or fastener was tightened sufficiently. Their failure can be the result of loose tightening.
Let’s take an example of two plates. The plates have a common joint point. The plates are clamped with the help of a bolt. If the joints get unloaded this means there was something wrong with the sufficient amount of force applied to the bolt. The clamping force between the plates will be absent in such a situation. Joint depression and joint separation are the two issues to be taken care of. In the situation when the joint decompression point is reached the additional loading is sustained by the bolts. And if the load is extra or it fluctuates the bolt will sustain a high alternating stress. It might result in a fatigue failure. And this is the most common resultant. This can be avoided by adequate tightening of the bolts. There will be no fatigue failure.
For the fasteners in service, the most common hurdle is fatigue. And the cause-the lack of bolt preload. This is a very common experience. The final words are: It should be ensured that fasteners are tightened sufficiently.
It is not that the tightening of bolts and fasteners will do. The quality of both must be good. Try buying or manufacturing high-quality products.