Posted by Avreet October 4, 2017
It’s hard enough just choosing the right fastener style, colour, coating, length and head, let alone worrying about them coming loose once secure.
When there is a gap between the thread on a screw, nut or bolt and the bearing surface it is loaded into, the fastener may, over time, either pull itself out, or take on too much of a load. That loading force can cause it to fracture.
Another thing which occasionally happens is the hole into which the fastener has been threaded can lose the ridges of its thread, and the fastener will simply slide back out if it has nothing to resist it.
Alternatively, there may be corrosion damage to the metal of your fastener causing the thread to be stripped.
What to do when you spot self-loosening
If you see self-loosening happening on your vehicle, deck or shelves and it is driving you ‘nuts,’ there are two main options – 1) Use double nuts, which provides a force pushing against the self-loosening strain, or 2) Use Nyloc nuts, which have a circle of plastic inside them to lock the nut in place.
Two nut solution
The effectiveness of this locking method isn’t just about tightening one nut down and then simply putting another tight nut on top. By placing the thin nut on first, when the thick nut is tightened on top of it, the thin nut starts to endure less load, less pressure and less stress.
Say you need two nuts to hold a bolt without fear of self-loosening. Place the thin nut on the bolt first and tighten it to between 25-50 percent. Then place a second, thicker nut on top. Hold the first, thinner nut to prevent rotation, with a spanner, and give the thicker nut plenty of torque. This shifts the load from the pressure flanks of the thin nut. You can now stop, because subsequent overtightening can cause excessive, damaging stress on the bolt as well as the thin nut.
Relative thread movement is not possible when the nuts are tightened in this way.
Nyloc nuts: a tight solution
Nyloc nuts have a plastic insert which works by letting the polymer (nylon plastic) spread elastically over the thread of your screw or bolt without letting the polymer get cut by the thread. There is compact force combined with enhanced friction, and a seriously sticky nut that’s almost guaranteed to never wriggle loose.
Fixtures, fittings, fasteners, nails, bolts, screws – we always have a boutique range of these at Renovation Warehouse, and we’ll advise on what you need to secure anything you purchase from us which has special fastening requirements – for example, shake-proof nuts, shakeproof bolts, or even split washers.