On 10/05/2014 8:40 AM, nestork wrote:
;3292289 Wrote:
Instead of lock washers, some nuts use nylon inserts to keep them on.
How many times can one put the nut on -- and off in between -- and have
it still work well as a lock nut?. When does the nylon stop working?
B.
Well, after reading this:
'Nyloc nut - Wikipedia, the free encyclopedia'
(http://en.wikipedia.org/wiki/Nyloc_nut)
I would say that Nyloc nuts can be re-used very many times without
lessening the performance of the nut.
There seems to be a popular misconception about how these nuts work.
People tend to think that the screw or bolt threads CUT INTO the nylon,
and it's that deformation of the nylon around the screw or nut threads
that prevents the nut from coming loose. This is incorrect.
Apparantly, the screw threads DO NOT cut into the nylon at all.
Instead, the nylon ring stretches elastically over the screw threads.
In engineering terms, elastic deformation means that the nylon returns
to it's former size and shape once the force deforming it is removed.
So, there is no change in the nylon ring's ID or interior surface as a
result of screwing it onto a bolt or screw because all the deformation
is purely elastic.
Still, that same web page says that experts disagree on this point.
If'n it wuz me, I would re-use the nuts except for applications which
you feel are critical and warrant the small cost of using a new nut each
time.
My observation over the years has been that there is some thread-cutting
but it's quite minimal for quite a number of repetitions altho
eventually one will begin to notice some difference in torque required
if they are reused a quite large number of times. There's a filter
housing on the little JD utility tractor here that uses them -- it gets
checked about every 3-6 mo and is of early '90s vintage so that would
have a guesstimate of some 20yr*3/yr-- ~60 cycles so far. On these I'd
judge virtually no change in their characteristics to date. (They're
not large, 8 mm, but I've not reason to think any others would behave
much differently).
There are various other pieces of gear around that use them but no
others that get frequent use as these for comparison...altho I can't
recall when (or if) I've ever thought one needed replacing for having
worn the nylon insert out to the point it didn't function.
--