I
okay continuing with platings and
coatings in the passivation and pre
oxidation and right now perspiration so
we'll get rid of the coat and proceed
now stainless steel fasteners are
normally passivated or pre oxidized
during a manufacturing process to make
them more inert and of course I
mentioned earlier is done with the acid
treatment and then of course the pre
oxidation is just done simply by putting
them in a furnace and run them up to
about 1300 degrees and cooling them to
form an oxide coating on the surface the
advantages are that it deters galling
and it's a relatively inexpensive
process the disadvantage is that making
parts still need to be lubricated for
torque coefficient consistency and
here's the old familiar black oxide
coating with oil and it's nice and
pretty in black and you put oil on it
and it glistens and looks good but once
the oil is gone black oxide is worthless
it's real cheap no baking required after
plating it this the material strength is
less than 200 k SI and its disadvantages
it's worthless for corrosion prevention
once the oil is gone and the coating
doesn't adhere well to steal now here's
a bunch of miscellaneous platings and
coatings and electric lyst nickel is one
of them and it is used a lot on just
coating of steel where you don't have
threads but on threads it creates some
problems in that you can get uneven
plating on the threads so that they're
kind of out of tolerance this sir Mattel
sir Malloy is a aluminum inorganic
material
all that is used for corrosion
protection of both unthreaded and
threaded parts but once again if you
assemble reassemble very many times it
will come off synergistic because
another one is a combination of surface
oxidation and a fluoropolymer used for
corrosion protection and lubricity but
these are assembly reassembly none of
these work that well on proposed
replacements for cadmium of course the
there's been a big push to do away with
cadmium because it is such a bad thing
environmentally so there's not fit over
in chardon came up with this dr. Matt
320 with the plus a ol sealer as a
proprietary thing for the automotive
companies and it has metal oxide zinc
and aluminum and a clear sealer it's
good up to 600 degrees but the coating
is damaged by assembly disassembly
cycles and it will support fungus growth
and it costs about the same as cadmium
so the cost savings isn't there the only
thing that it's kinder to the
environment zinc nickel coating is one
that is used some there's about ninety
percent ten percent nickel but it
doesn't work very well on fasteners it
works on rods and things of this nature
now here is a summary of pleadings and
coatings and the thing that is most
important here is the useful design
temperature limit you will notice that
most of these don't go that high and the
a here is for the black oxide with oil
as soon as the oil boils off your
corrosion resistance it's gone so you
see when you get down to it about 1,200
degrees is the best that any of these
will do so that's why that in a lot of
cases where you
super high temperatures you have to use
a material that doesn't require coding
like wasp a lawyer Hanes or inconel or
something of that nature because you
can't rely on the coatings now here's a
table that just gives various
characteristics of the coatings and
plated there's a couple here that i
wanted to mention era date is a common
coating in fact we used it on the CM one
chamber for it is electrically
conductive whereas anodized isn't and it
is a type of chromate conversion coating
in which you actually treat the surface
with an acid to form a real thin layer
that is somewhat corrosion resistant so
what we had to do in in on CM one you
mask it in the irritated areas where you
have electrical conductivity required
and then the anodized which is actually
used although it's used on other
materials as we know it as being used on
aluminum it is a acid etch using
sulfuric acid I believe that forms a
fairly heavy oxide coating and fact you
can't anodized a fastener because the
anodized is thick and well you can
anodized it physically but it doesn't
work out very well on the threaded areas
because you will have a to heavier
coating and the threads where it doesn't
work too well now moving on to thread
lubricants there's all kinds of
lubricants available and of course all
of us have used the old 10w30 oil and
for our cars to lubricate stuff the oil
grease wax graphite silver molybdenum
disulphide and prep proprietary types
such as never sees silver goop
synergistic can ever lube and so
on some of these are applied at
installation and some are cured on the
fastener by the manufacturer I'm having
trouble turning my page okay for oil and
grease you have good lubrication up to
the boiling point of the oil or grease
which is usually around 250 degrees and
of course you can't use any of this
stuff in vacuum now graphite graphite
drag graphite is not dry it's a fine
carbon powder that needs moisture
usually oil or water to become a
lubricant and then when the moisture
evaporates it becomes an abrasive powder
and of course it can't be using a vacuum
either silver plating as I mentioned
earlier it is normally used on stainless
nuts stainless bolts as both a lubricant
and I Colleen coating and it's good up
to about 1600 degrees it can be used in
a vacuum but it is very expensive
molybdenum disulfide is kind of a
universal tape that's used in the
aerospace industry because it's a can be
put on us a dry film lubricant it's good
up to 750 degrees it can be used in a
vacuum and it can be applied to both
alloy steel and stainless steel now
never sees is a proprietary petroleum
based lubricant and it contains metal
oxide usually copper or nickel depending
on what temperature you want because the
copper of course has a lower melting
point than the nickel and it's good up
to 2,200 degrees because what you wind
up with is the metal flakes between the
threads as the oil it boils off and so
this means that you have to reapply each
time you reassemble it and it can't be
using a vacuum either but
you have the the flakes in between the
threads making them easier to
disassemble silver goop which is made by
some company here in Cleveland I believe
is a proprietary paste that contains
twenty to thirty percent silver and it's
good up to about 1500 degrees but of
course silver does not is corrosive to
aluminum magnesium so you don't don't
use it on them it's curse the silver
goop is very expensive and it can't be
using a vacuum either the fluorocarbon
coatings there's a lot of them available
the I'm just listing a few of them here
the synergistic span coke style garden
ever lube and they're only good for a
few assemblies because they flake off if
you assemble and disassemble a fastener
nut bolt very much and there are only
good up to about 400 degrees they can be
used in a vacuum and here was one that I
learned when I was looking for different
types of lubricants for high temperature
applications plain ol milk of magnesia
is used by the turbine engine companies
for engine assembly because anything
that you use in a jet engine for
lubricants going to burn off anyway
after the things operating but in
putting it together this is a suitable
lubricant and it doesn't harm anything
when it burns up now here's a summary of
the thread lubricants and most of stuff
we have covered here there this is
doesn't necessarily include all of them
but these are the the common ones and
once again there's very few that are
good for high temperatures here are the
three that are good for the high
temperatures so
this is something you have to keep in
mind that going back to that original
principle that the first thing you want
to do is establish the environment that
you're going to have your fasteners in
now going into the subject of corrosion
of course this is a major field so we
just try to hit it a little here in the
way of fastener corrosion galvanic and
stress corrosion we've already covered
and the corrosion resistance of a
particular metal to occur rodent can be
found in a book of tables which I will
be leaving behind when I retire there is
a two-volume set that actually gives for
the different percentages of different
types of corrodens it gives the effect
on the various materials and hydrogen
embrittlement and graphite corrosion
will be covered in the corrosion section
here hydrogen embrittlement it's talked
about a lot in recent years and yet you
can test for it but it's kind of UFO
like a UFO it's kind of hard to find
it's caused by having free hydrogen ions
in the presence of the metal which in
most of the time it's steel it causes
problems in during the manufacturing or
plating process the higher the strength
of the material the more sensitive it is
the hydrogen embrittlement you can get a
hydrogen chemical reaction in which it
combines with the carbon in the steel to
form methane gas or are hydrogen niobium
columbium same thing the English call it
niobium the Americans call it Colombian
or tantalum to form hydrides the methane
gas can cause cracks and the hydrides
are weaker than the parent material so
they can weaken the material then you
can get hydrogen blistering where the
atomic hydrogen fuses into the material
and combines in the moloch
tools and then the molecule is bigger so
it can't get back out so it will build
up pressure to create blisters that will
eventually cause cracks and here's the
problem there's no external indication
that hydrogen is present you can't look
at it you can't run it through x-ray
machine anything like that and find out
that it's there so the only thing that
you can do is test for it enjoy they
test fasteners for hydrogen
embrittlement they put them on a fixture
there's an ASTM spec which I'm not don't
remember the number of it you actually
put them on with a wedge type washer and
take them down and leave them for I
think it's 48 hours or something like
that if the head didn't pop off it
passed the test and that's that's so
what they do on testing for hydrogen
embrittlement is just take a bunch of
samples and test them that way to see if
if they can find where any of them have
embrittlement now on hydrogen
environment embrittlement usually you
wouldn't run into that because it takes
high-pressure hydrogen to cause that so
if you had a tank of some kind of high
pressure tank that you had fasteners
holding something together inside then
you could actually get hydrogen into the
fasteners just from the high pressure in
other words we're assuming there there
was no hydrogen embrittlement in the
fastener before it was installed then
you need about 2,000 psi hydrogen in
order for it to go in the material after
it's installed so that's not likely to
happen but hydrogen embrittlement is
always a problem because it depends on
how good the manufacturer was at making
the part so here are some percussions
use the killed steals coat and plate the
fasteners bake the hydrogen out within
two hours after plating otherwise you
can't
take it out Taylor the plating bath to
minimize free hydrogen ions and avoid
the use of alloy steel fasteners above
190 KSA because the only way you can
plate without getting hydrogen
embrittlement is to do it in a vacuum
atmosphere then use stainless steels
that are not sensitive to hydrogen
embrittlement and run the tests to see
if you can find any evidence of any
embrittlement here's one that is
slightly different in your book that had
had a revised it at the last minute the
definition of the graphite here just to
indicate what it is it it's a actually
to drive dry film carbon lubricant which
can cause corrosion when exposed to
moisture because the on some materials
and it can cause you problems and I
realize that they put out a la keys or
used to put it up which is a graphite in
oil to use for locks but yet it will
corrode some types of locks so a guy but
the name of Gilbert gave a course on
corrosion here several years back and he
pointed that out that graphite was a
no-no for lubrication of locks for that
reason because it'll actually corrode a
lot and one of the things then this
happened to us on one of the turbine
engine programs around here is dry
graphite is an abrasive so if you cook
it and dry it out now you have a carbon
powder abrasive which is does a lot more
harm than good and here's something I
threw in just just for your information
I had run into this in a failure course
that I took d zinc tification it's kind
of an odd word but you can actually get
in a material that has
it's even used for just removal of a
particular element from a material by
corrosion but usually it's the removal
of zinc from brass by chemical action
leaves a brittle shell of copper and I
saw on the samples the guy had and you
could compare it to what happens to a
wet piece of wood once the carpenter
ants get done with it it's just a shell
that you can crush and rather rather
striking to look at a failed piece like
that so here's the the galvanic series
which I had been talking about earlier
in fact I believe we showed it earlier
that shows the different materials now
of course magnesium is right at the top
and magnesium is a disaster in a
corrosive environment in fact this guy
who taught a course on failure analysis
pointed out that when an airplane goes
down in the ocean one of the ways if it
that they look for it is if it had zinc
components in it the zinc will decompose
so fast in the saltwater that you will
have bubbles coming up out of the ocean
and they can look for it so magnesium
I'm a member of the mill handbook five
committee I don't know whether some of
you are familiar with it or not but
anyway it is kind of the Bible the
aerospace materials world and magnesium
is kinda out of usage by the aircraft
manufacturers for this reason because it
is so hard to protect it from corrosion
and it's it's not used in any primary
structure that I know of on any of the
airplanes okay going on to locking
methods in most any application some
type of locking must be used prevent the
fastener from loosening
underload and without a locking device
of course the only resistance you have
is just head friction and the nut
friction which if you are vibrating it
very much at all is not enough now find
threads give you slightly better
resistance to loosening from vibration
than course threads but it's not a lot
due to the flatter angle of the threads
and one of the things that you try to do
and this'll this'll help you once in a
while is to mount bolts with the heads
up to lessen the loss of loose bolts
because sometimes maybe you'll find
something on your car that the nuts gone
but the bolts still hanging there
flopping back and forth and you can go
ahead and put lock that on it now here's
here's one of the most common type of
locking methods is deformed thread and
what you do with the nut it's usually on
the net after you have formed it the
last operation you actually hit it from
two sides and make it slightly oval then
when you put it on and this this hits
got to be controlled to because
otherwise you can be in heap of trouble
it will kind of go back to circular
again so let's see initially here it is
oval then when you put the thing on it
goes the circular it will actually be
for them enough and of course when it
does that the threads will lock up on
the bolt then when you take it off it
will go back to oval again so you can
use this one all around ten times before
it loses its locking capability because
eventually putting it on and off you're
going to yield it back to the circular
condition and it will no longer lock but
that's one of the good ones and you can
buy
the forum thread lock nut set your
hardware store now here is the locking
collar tight and although I didn't call
it out your elastic stop net is one of
the biggest manufacturers of these what
you have is you have a fiber or nylon
collar here in the top of it the caller
has a smaller diameter then the the bolt
thread so when you run the bolt in it
will interfere on that collar and it'll
also provide a little bit of sealing if
you kind of seal from getting water in
there to give you that much ceiling
although it's not for pressure or
anything like that but the only problem
is this collar area is usually only good
for about 250 degrees to where it will
start softening up to where to become
ineffective now here's the split beam
lock nut this is one that works quite
well and what you have you have a
smaller diameter at the top of it and
its salt cut so that when you put it on
it'll spin freely till it gets up to
that area then as you tighten it up the
beams if you will these six beams on it
have to deflect outward in order for the
bolt to go through so once again this
gives you a pretty heavy friction load
on the threads and will lock it in place
I had a personal experience with the one
of these on a car that I had that the
shock absorbers didn't want to stay on
it and I put these split beam lock nuts
on it and that held versus the the jam
nut to which I'll cover later now here's
a nighlok pellet nighlok is the biggest
manufacturer of this type of thing
although it's even covered by a milspec
so there's a lot of people in on the act
on making it this way but what do you do
is you you cut a little hole in the
thread and stick a nighlok plug in it
and this plug sticks up past the thread
so when you when you put it on the nylon
will bind up in the threads and cause it
to lock this one is a fairly good cheap
way of locking stuff using on a bicycle
lawnmower or something like that it'll
hold up but once again the temperature
range on it is kind of low because nylon
as starts getting soft about 250 degrees
and of course the threads will chew it
up so you can't put the thing on take it
off very many times without run into
trouble now here's luck tight which we
use around here all the time that's
actually a trade name but different
people make this it's actually a a one
one component type adhesive that you
just smear on the fastener before you
assemble it and it's made in different
grades so that if you want to remove the
fastener you use the volesse sticky tape
like an in Lafayette I think 242 is
removable and 271 as the tamper-proof
fasteners and there's another one in but
to another one or two in between there
four bolts that you just want to make
difficult to get off but some of the
manufacturers other manufacturers of
this are Bostick in the industry's
nighlok 3m velcro and perma bond and
lock tight is good up to about 400
degrees now a poxy ribbon this is used a
lot on bolts you get them and they have
to to ribbons of epoxy so that you have
the main one and then you have the
hardener that goes with it and this way
you can store them it has a shelf life
at least that you can keep them for I
think up the years like that and the
epoxy is mixed when you install it so it
will combine in
a hardon to hold the fastener in place
now of course this type once you would
remove it it would have to be replaced
because it you destroyed the seal
because it's a one-time type thing and
the maximum operating temperature on
these is also about 400 degrees here is
another type of thread as a special
thread spiral lock I think Detroit
tappan dies the holder the patent on
this one and this is a cross section
here of a kept thread and a fastener now
the problem with this when you install
it is you have to have spiral locks tap
because this is an oddball see the
thread the tap cold is not fit the
thread and you get your locking action
by actually wedging the ramp of the
thread up against the oddball tape tap
and but you can distribute over several
threads so it offers better locking
capability than ordinary thread would
and some people have used it and run
vibration tests and it holds up fairly
well but of course the the disadvantage
is that you can't you have to get their
tap to tap the whole initially and and
so that creates a problem sometimes for
people on universal type of sembly on
the direct interfering thread in this
case you just have a fastener that is
made deliberately with an oversized root
diameter to give a slight interference
fit to lock now some studs that you have
where you have a stud that is installed
in something and you want to leave it in
place you use this type of thread so
that it will not come out when you take
the nut off the other end the tapered
thread
is kind of a variation of this and what
you actually tapert this is a smaller
diameter up in here and then when you
put it together it has to push the
threads out here and that gives you a
locking force on it now here's one that
we covered in the drafting room manual
stuff run Roman check that we we fought
semantics on that one a lot whether it's
a castle nut or a castellated nut so
since I wrote this I put my preferences
castellated nut with a cotter pin this
is used a lot for installing bearings
and things like that where you don't
want to tighten it very tight but you
want it to stay put once you tighten it
so you can take the nut up then to the
to the Turk you want then back it off or
taking it to the next next spot on it to
get you a slot because you only have a
single hole drilled in the end of the
fastener so you line up one of these
with that hole then put a cotter
pin in it and it will hold it in place
at the exact spot that you said it and
this way when your for instance a lot of
the cars are made this way there's
another way that would be my next slide
I think but on wheel bearing when you
tighten it up usually you tighten it up
tight seek the bearings then back it off
enough to let it spin so the nut is a
little more than finger tight now here's
a nut here's another one that is used
for the same reason evidently this is
cheaper because you're doing the same
thing with a regular nut then you're
taking this nut cap which is a sheet
metal stamp sheet metal piece but it has
the serrations here with the slot senate
that you can put the cotter pin in
so you Turk the nut to the spot you want
it then slip this thing over it then put
the cotter pin through the hole in the
axle or shaft whatever it is and fasten
it the same way as we did on the other
one and of course the reason that grease
cap is on there is i got this diagram
from a truck manual and i didn't
separate the grease cap from it that
goes on after you've installed
everything else now here is luck wearing
which is normally used just by the
aerospace industry because of the cost
and labor involved because you are
winding these wires on here through
either holes straight through the top of
the heads or in the case of the nut
holes through the corners of the nuts
you put these on in such a pattern that
if you try to loosen one fastener it
tightens the other one this way they
can't loosen because they're all tied
together and this is a method that is
covered by an MS spec 30 35 40 you can
use it quite well where you have a
circular pattern of fasteners on a
flange or something like that but the
only people that use it in normal cases
as the aerospace industry here is an
alternative method to the lock wearing
this is a similar thing in which you
start out with a piece of cable by the
Bergen cable company here that has a
barrel already switched in place on it
so you just feed it through you run the
wire through the heads to wind them the
same way so that one can't loosen
without tightening the other one then
when you get to the end you have a
machine similar to a rivet gun or
something that actually puts a barrel on
here pulls the right tension on the wire
and closes it off so that this is
actually a faster and cheaper way of
luck wearing than the standard luck
wearing method with the twisted wire
this is the disc lock washer it is a
little bit cumbersome in that you have a
pair of washers together and these lines
here represent the angles on them where
you put the two together and turn them
together now as long as you keep them
together they can't rotate with with
respect to each other so the angle of
this ramp is steeper than the angle of
the thread so it will keep it from
turning however the bottom and top of
those two washers have to have
serrations on them that bite in the
joint material and also the bottom of
the nut in order to keep it from
slipping with respect to the nut or the
joint otherwise the washer will spend as
a unit and doesn't help you any so so
that one will work if you are not
concerned with carrying the coating
loose on the surfaces here is a kind of
a take-off on the disc lock washers in
that you have a nut assembly now this
one has the ramp cheer and the lower
part of it from here down is not
threaded just the upper parts threaded
well to see you put the two of them
together you put them on with a socket
extends down over both of them now this
will hold the thing while you twurk it
up and then of course the bottom surface
of it has in serrations on it that bite
into the attaching plane of the joint so
once again you're scratching the surface
you're attaching to however a company on
the west coast makes these and the
president of it told me that they had
they were selling millions of these for
the heavy truck industry
because the heavy truck industries had a
lot of trouble through the years with
nuts coming off and wheels coming off so
so they're paying for this type of nut
in order to hold them on because they do
work on holding truck wheels on here is
a another method this is a durar lock
nut which is a trademark of SPS which
one of the one of the big manufacturers
of fasteners it has serrations on it
here that bite into the surface so that
it will not slip and start loosening up
once you get it tight now you have to
depend on this embedment of the
serrations in the contact surfaces and
so it will scratch up the surface if you
can live with that this one will do a
pretty good job of locking here are two
flock washers which are common in the
electrical and automotive industry
because they do afford locking oh and
but once again they do it by gouging
into things they these teeth are twisted
although this doesn't show it they're
actually twisted so that you have one
surface bites into the fastener the
other one bites into the surface that
it's up against so that it will get
enough bite on both of them to hold them
in place and prevent rotation however
you damage the surface quite a bit now
this one is also available with teeth on
the inside so that the outside is smooth
in areas where you don't have room
enough to have it stick out that much
you can you can get them with the teeth
on the inside
here is the old famous jam nut which is
one that if I polled the people in the
audience neither one would be able to
give me a positive answer on which side
you put this and whether you put it here
where it's showing or you've already put
the big one on the inside and the little
one on the outside because the experts
can agree on that it's difficult to load
each one of these so that it'll carry
any load compared to the other ones
because if you if you tighten this one
tight it will unload this one and if you
don't tighten it enough then the two of
them will not work together so it's very
difficult to get both of these loaded to
where they would carry a load so jam
nuts in my opinion are not to be used
for critical designs unless it's
something like locking a turnbuckle or
some sort of a rod where something else
carries all the load and you're just
pushing this up against it to keep it
from working loose and here is the good
old split helical up were sure which is
a misnomer because once you compress it
under normal bolt torque it will flatten
out and then this is the flat washer
anyway which doesn't do anything for you
and vibration testing of the split lock
washers assemblies indicate that they're
about us the same as a flat 4shared
resist vibration and I don't recommend
them for any kind of a locking situation
although I was sharply criticized for
writing this in a fastener magazine
because the person who wrote in the
criticism was a manufacturer of split
lock washers so he didn't like it
because I said his his product was
worthless for locking now here is a
method that is used some but it's kind
of a going a long ways to do your
locking as I see it it
this is a trademark of some company on
the west coast age 8 and you see what
you have is a special boat that has a
kind of the double-headed one with a
groove machined in it which creates the
little problem on initial manufacturing
then you have a retainer plate that
slides down over this outer head on to
the bottom one then you use this snap
ring to put in that groove to lock the
thing in place now you do this after
you've already took the bolt to the spot
that you want it now the only thing is
you have to have something for this to
brace against to keep the bolt from
backing off so it has to be a special
design in that respect and then the
other problem that I had on the control
arms on a Ford wagon this retainer plate
is made out of sheet metal over a period
of time it will rust up on you and then
you go to loosen this thing for a front
end alignment and the retainer plate
comes off and you can't get in there to
get anything else on it loosen it so
that one is one that I would not
recommend in any environment where you
would have corrosion now getting into
washers and out some of them we've
already covered so we won't do a lot on
summon the most of them are flat they're
used to provide a hardened smooth
surface for the contact of a fastener
header nut and that's that's really one
of the the main reasons for using
worships both under the head and the nut
is if if you are rotating either one
usually the joint surface is not as
strong as the fastener so therefore you
you have to have that too
avoid embedment and then here's another
one for shade tree mechanics if you have
a washer under a bolt and it's rusted in
place usually you can take a cold chisel
and a hammer and not the washer
laterally and get it get it loosened
some so that you can loosen the bolt and
washer now here's the plain flat and
countersunk type for sures the here this
is the ordinary hardware store variety
and they're covered by all kinds of
standards there's msan antsy so on which
defines the outside diameter inside
diameter and thickness for a given size
so so normally you can just call out a
dash number from one of these specs and
your your cupboard the counter sunk
coursers are made with the countersink
in them we're on a high-strength boat
you have a larger radius under the head
so you don't want point contact if it is
this diameter is tight you could get
point contact on the head radius so you
want to counter sunk so that it will now
distribute the load better under the
head and you won't have that high stress
concentration at the radius now on the
course we covered the split lock washer
the tooth lock washer and the disc lock
washer I just wanted to point out that
we'd already covered those in case
somebody would wonder if why we hadn't
then we go on to a another unique type
and this is used a lot in the
construction business the DTI of worship
the direct tension indicating it is a
flat ground washer that has these bumps
stamped on it and but you have to use
regular washers in addition to these in
order to distribute the load properly
because you don't want these grinding
against the head or not of your boat
and actually these are manufactured and
they do tests to determine the loads on
them if we're the amount of compression
that you get on the bumps determines the
axial load in the bolt so you took the
thing with a torque wrench without
reading the torque unless you want to
down to the point that you have a
certain gap left and underneath the
washer and the bumps and you measure it
with a feeler gauge so this way
regardless of the coefficients of
friction on the threads or the head or
anything you can actually torque it down
to where the gap you get will tell you
how much axial load you have in the bowl
now here's our old familiar belleville
washers that named after the inventor
who invented them way back in 1867 so
they've been around a while it's also
known as a comb washer or spring washer
and these are designed with a load
preload determination for a given washer
or how much it takes the platen it and
it will flatten elastically so a lot of
times you can use them in a critical
application where you want to limit the
amount of axial load you have if you put
a Belleville washer on and tell the
mechanic okay just perk this thing until
the washer starts to go flat and then
quit regardless of what your torque
wrench says it also can be used for
absorbing differential thermal expansion
between fastener and joint material for
instance if you're bolding big joints
with of aluminum with steel bolts so you
have a different coefficient of
expansion and contraction you can put
belleville washers on to absorb
some of this a thermal expansion to keep
from overloading or under loading the
joint you can use them in stacks in
series or parallel in order to an in
effect use them to become a spring now
here's another one is that is kind of an
oddball you don't see them around very
much because they're expensive a
self-aligning moisture you can use these
on a structural shaped flange which is
used usually has some taper to it and
the reason they're so expensive is the
washer and nut ermichine that's an
assembly so you actually have a cone
here two cousins that are rotating
together to give you the proper
alignment so that you still get axial
loading on your boat instead of putting
bending on it and this will take up to
eight degrees maximum misalignment I
don't remember now what the angle is on
the i-beams and stuff like that I think
it's less than that i believe it's like
a 325 degree or something like that
paper on the flange at seven now this is
this is another one that gives you a
axial reading without using a torque
wrench and this is a PL PL I preload
indicating that SPS has the patent on
and on this one you have a regular
washer a soft inner ring and then a ring
that goes around that it has capstan
holes in it and then a regular washer
and you put all this assembly on you
tighten it down and the this inner ring
is actually a load cell if you will in
that for a given amount of compression
it has been pre calculated the amount of
load that it takes to give you that
compression so you can press it down to
where this outer washer the cap span
ring and the regular were sure are
grinding against each other and we'll
turn that means that this thing is
compressed down to where you bottom
doubt on this so you check the thing you
can't turn that ring any longer you know
you've got it to a certain axial load
and they haven't color coded and
available in all kinds of materials so
that you can get them to use where you
want to determine the load and there's
really no good way of doing it as far as
measuring it now going to inserts which
is a very common thing around here in
the airspace world an insert is actually
it's a special bushing that's threaded
on the inside diameter and locked with
threads or protrusions or a combination
on the outside diameter and installed in
a drilled molded or tapped hole it's
used to provide a strong wear resistant
tapped hole in a softer material
normally than the fastener and you can
also use them to repair stripped threads
where you've stripped the threads in a
whole rather than going to the next
bigger size in taps you can put an
insert in without opening the hole up as
much in fact one of the places you use
them is when people strip the spark plug
holes in aluminum engines a lot of the
times they use in hela coil or Keynes
herders and I pletely use hela coils
most the time for that and in general
they're the two types the one that is
threaded externally and those that are
locked by some method other than threads
and we'll go into them and you get self
tapping and all that sort of thing too
now the earth space industry uses
inserts and tapped holes and soft
materials in order to
increase the load carrying capability is
pull out and this way you can use a
smaller fastener and put in an insert
and since the insert is normally about
an eighth of an inch bigger in diameter
than the internal thread in it you can
take a 1032 bolt and install it in like
an equivalent five sixteenths kept hole
here is one of the most common one and
the generic name is key insert although
some call them a solid threaded bushing
or whatever and the insert we usually
have external locking tangs that's these
things you see here and when you install
them after they're threaded in you pound
those that there's a tool for pounding
those down and they extend actually
passed the threads you're the root
diameter the threads to give you locking
capability the the bigger diameters will
have four of those on them whereas the
smaller ones will have to and of course
you can get them that are not locking at
all that you use some other method of
triangle up the external thread on them
now they are very labor-intensive to
install so you don't install them unless
you have to here is the other type the
Gila coil which is I believe now owned
by Black & Decker i think is the owner
of the patent but they're also called a
wire thread and it's usually made of
stainless steel and has a diamond-shaped
cross section that will actually form
internal and external threads when
install and it's like like taking a
spring if you will and winding it down
into a hole and the Diamonds section
part on the back goes into the existing
threads and then the diamond section on
the inside is your thread diameter that
you put your fastener in now they're
usually coated to deter her
ocean and seizing and you can get them
both in locking and unlocking you see if
you look at this this is the non locking
here and this is a locking you actually
have some deform coils down in here in
this installment Tang which you may not
may or may not be able to see on here
it's broken off after installation now
well the the difference between the Gila
coil and the key insert the Keen cert is
only available in one length for a size
the Gila coils you can get them in
different lengths you can get them up to
from 1 D 2 3 D length where D is the
diameter of the fastener and another
thing of course you need a to open the
hole up less where you put a Gila coil
in so if you're repairing stripped
threads in an area where you don't have
a lot of room you can recap the whole
just slightly and get it opened up
enough that you can put a Gila coil in
it
here's a kind of a more rare tape this
is a locking tape insert in which you
have the split beam nut machined on the
bottom of it remember I showed you the
slip split beam lock nut earlier and so
that you have the locking capability but
of course you are have a longer insert
because of this thing having to be
installed because this is not threaded
into the hole and these are made
primarily for aerospace usage out of
either eight to eighty six or inconel
718 and since you have less external
thread you have to be careful in soft
materials to make sure that you don't
exceed the pullout allowable when you
install a bolt in them because the
because of the split beam increasing the
overall length and here is one that
solves some problems but it also creates
some others the floating insert of
course if you're using and i'll be
covering us later on with if you're
using counter sunk or flathead fasteners
the countersink tries to sulfa line
fastener if you're going into a rigid
pepto now you have the two of them
working against each other which is not
too good well this solves that problem
in that the insert is in you have
actually an insert in the bottom of this
one so that it's externally threaded
just like the regular teen cert then you
have this little jobby that floats down
in here and so this will give you some
self-alignment when when using
countersunk fasteners but by putting all
of this in it it since this has to float
inside the main king cert you have a
smaller diameter
internally for a given diameter
externally so therefore you're losing
some to put that floating capability in
you're losing some so you might wind up
having to go to a larger diameter insert
externally then you nor normally would
use now here's the self-tapping inserts
this is usually a self or so solid
bushing with either tapered external
threads like a self-tapping screw like
this or you can have and you can have
them also solid with a nighlok pelletier
for locking them or you can have one
that they use in plastic quite a bit
what they call a speed cert and this is
used I think for like in electrical
circuit boards and stuff like that it
you drill a hole and you actually can
push self tap the thing by deforming the
plastic without generating any shavings
so we will continue next with the Sun
threaded insert so we'll take a break
but right now