Chain waxing + graphite question

[41]

Jim Smith wrote:
> "41" <[email protected]> writes:
>
> > Jim Smith wrote:
> >> "41" <[email protected]> writes:
> >>
> >> > Have you ever rubbed paraffin, better, under some pressure, whether
> >> > between fingers or between links? It is not slippery. That people have
> >> > yet to consider this elementary fact still amazes me.
> >>
> >> On the other hand, anyone who has ever rubbed the threads of a screw
> >> on a block of parafin before driving it into a pilot hole in hard oak
> >> or maple, or who has ever waxed the sash in an old-fashined wooden
> >> double-hung window might draw a differant conclusion.
> >
> > I will recycle a reply of mine from elsewhere:
> >
> > #What is or is not a lubricant obviously depends upon context, meaning
> > #the friction pair and the pressure. For example, sand is not generally
> >
> > #considered a lubricant, and I expect you wouldn't have gone after me
> > if
> > #I had said SAND IS NOT A LUBRICANT, but it will reduce friction if
> > #interposed between the adhesive sides of two pieces of Scotch tape, or
> >
> > #for that matter, between a shoe and a dry sidewalk- or a tire and
> > same.
> > #We are talking here about bicycle chains. Coefficients of friction
> > vary
> > #wildly depending on the precise context
> >
> > Clearly the whole reason (apart from use as a sealant or moisture
> > barrier) for rubbing paraffin on these pairs, instead of simply leaving
> > them alone, is that their friction is really high. I.e. paraffin is not
> > slippery, but these pairs are even not slipperier still. However, this
> > is not the case for bicycle chains, as proved in the IHPVA paper.
>
> Sure. My question is why you felt it so important for folks to rub it
> between their fingers?

Fair point. It was just because it had a low get-off-butt-and-try
threshold. I

 

[41]

HarryB wrote:
> On Fri, 03 Mar 2006 17:30:29 -0600, Patrick Lamb
> <[email protected]> wrote:
> [snip]
> >I don't think any proponents of waxing the chain on this group have
> >advocated pure paraffin.
> >
> For the record: I use only "highly refined paraffin wax" (description
> printed on outside of box) and am pleased with the results. To date, I
> rode 488 miles on the one bike and 511 miles on the other since I have
> waxed those chains. And I don't plan on waxing tonight.

Thanks for the update and data points.

> >
> >I'm glad to see you admit that you're
> >arguing against a straw man, and have not comment on how well a
> >paraffin/oil mixture works.

 

[Sandy]

Dans le message de news:[email protected],
HarryB <[email protected]> a réfléchi, et puis a déclaré :
> On Fri, 03 Mar 2006 17:30:29 -0600, Patrick Lamb
> <[email protected]> wrote:
> [snip]
>> I don't think any proponents of waxing the chain on this group have
>> advocated pure paraffin.
>>
> For the record: I use only "highly refined paraffin wax" (description
> printed on outside of box) and am pleased with the results. To date, I
> rode 488 miles on the one bike and 511 miles on the other since I have
> waxed those chains. And I don't plan on waxing tonight.

But is _she_ waxing ?
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

 

[41]

Peter Cole wrote:
> 41 wrote:
> > Peter Cole wrote:
>
> >>The phenomenon you are describing is viscosity.
> >
> >
> > Yes, consider that for a moment (although solid wax is not liquid, and
> > so the terms are toughness and hardness, not viscosity). I f you
> > penetrate the wax layer, you have to plough through it, instead of
> > sliding upon it, or rather upon the water or oil layer at its surface.
> > Chains are extemely high pressure environments. FK's experiments,
> > besides their oil layer, flout this condition. Think about it.C
> >
>
> When wax is used in a pressure bearing application the pressure
> typically melts the wax at the contact area.

A good point, if the pressure/temperature were sufficient. Suppose
indeed this were the case. But then, as a liquid, in a high pressure
situation, it would flow out of the contact surface. But then, it would
no longer be under pressure, and recrystallize, and be incapable of
flowing back in.

As JB says, lubrication is a complex and not-too-well understood
subject (not just because of flunked literacy tests, but at the
fundamental level), but stepping back a bit and considering a few
elementary things can sometimes clear a lot up. I've asked this before
but received no response:

-Paraffin users agree it is no good in the rain:
-----------------------------------------------------------------
#I don't add graphite and don't see what is would do. I do add maybe
#5% motor oil to the wax. Parrafin wax is a bad lubricant. When a
#part gets scratched, the wax doesn't flow into the sratch. Maybe the
#small amount of oil in the wax will do that. I've had great luck in
#waxing chains in SoCal, where it is dry. I usually rewax when the
#chain squeeks. Getting caught in the rain will ruin a wax job almost
#instantly. I rode a waxed tandem chain in the rain one day. Next
#morning the dried chain already had rust spots.
-----------------------------------------------------------------

Yet, paraffin is not dissolved by water and is extremely hydrophobic.
So why do paraffined chains so quickly squeak and rust in the rain?
Think about it.

 

[[email protected]]

George King writes:

>>> Have you ever rubbed paraffin, better, under some pressure,
>>> whether between fingers or between links? It is not slippery. That
>>> people have yet to consider this elementary fact still amazes me.

>> On the other hand, anyone who has ever rubbed the threads of a
>> screw on a block of parafin before driving it into a pilot hole in
>> hard oak or maple, or who has ever waxed the sash in an
>> old-fashined wooden double-hung window might draw a differant
>> conclusion.

> I will recycle a reply of mine from elsewhere:

# What is or is not a lubricant obviously depends upon context,
# meaning the friction pair and the pressure. For example, sand is
# not generally considered a lubricant, and I expect you wouldn't have
# gone after me if I had said SAND IS NOT A LUBRICANT, but it will
# reduce friction if interposed between the adhesive sides of two
# pieces of Scotch tape, or for that matter, between a shoe and a dry
# sidewalk- or a tire and same. We are talking here about bicycle
# chains. Coefficients of friction vary wildly depending on the
# precise context

Hold it! As I said, this is delving into tribology and from what I
read here tribological definitions are missing. The concept of "third
body lubricants" includes materials like sand. Although abrasive,
such particles work as friction reducers both in the sandy road
surface and for instance, in hard disk storage medium in which wear
debris reduces friction between transducer sliders and disk.

> Clearly the whole reason (apart from use as a sealant or moisture
> barrier) for rubbing paraffin on these pairs, instead of simply
> leaving them alone, is that their friction is really high. I.e.
> paraffin is not slippery, but these pairs are even not slipperier
> still. However, this is not the case for bicycle chains, as proved
> in the IHPVA paper.

You might consider how two solid materials slide on one another. In
all cases, one or both materials flow at flash-points if there is no
separating lubricant. Asperity contacts cause temperatures many times
higher than the apparent bulk temperature and these serve to cause
local melting. Typically, disk brake rotors exhibit all the smooth
characteristics of molten metal surfaces although they are not
considered to operate in that mode.

Wax definitely flows and in thin films must melt to do so. Looking at
bulk temperatures does not reveal what occurs at the sliding
interface.

Jobst Brandt

 

[Peter Cole]

41 wrote:
> Peter Cole wrote:
>
>>41 wrote:
>>
>>>Peter Cole wrote:
>>
>>>>The phenomenon you are describing is viscosity.
>>>
>>>
>>>Yes, consider that for a moment (although solid wax is not liquid, and
>>>so the terms are toughness and hardness, not viscosity). I f you
>>>penetrate the wax layer, you have to plough through it, instead of
>>>sliding upon it, or rather upon the water or oil layer at its surface.
>>>Chains are extemely high pressure environments. FK's experiments,
>>>besides their oil layer, flout this condition. Think about it.C
>>>
>>
>>When wax is used in a pressure bearing application the pressure
>>typically melts the wax at the contact area.
>
> A good point, if the pressure/temperature were sufficient. Suppose
> indeed this were the case. But then, as a liquid, in a high pressure
> situation, it would flow out of the contact surface. But then, it would
> no longer be under pressure, and recrystallize, and be incapable of
> flowing back in.

Since soaking a chain in liquid wax (or the equivalent) deposits a fair
amount of wax in the various clearances in the chain, I would assume
that normal link articulation would replenish the film just from
rotational contact on those reservoirs. Speculation on my part, but I
don't know how the proponents of the technique would get the claimed
durability otherwise.


> As JB says, lubrication is a complex and not-too-well understood
> subject (not just because of flunked literacy tests, but at the
> fundamental level), but stepping back a bit and considering a few
> elementary things can sometimes clear a lot up. I've asked this before
> but received no response:
>
> -Paraffin users agree it is no good in the rain:
> -----------------------------------------------------------------
> #I don't add graphite and don't see what is would do. I do add maybe
> #5% motor oil to the wax. Parrafin wax is a bad lubricant. When a
> #part gets scratched, the wax doesn't flow into the sratch. Maybe the
> #small amount of oil in the wax will do that. I've had great luck in
> #waxing chains in SoCal, where it is dry. I usually rewax when the
> #chain squeeks. Getting caught in the rain will ruin a wax job almost
> #instantly. I rode a waxed tandem chain in the rain one day. Next
> #morning the dried chain already had rust spots.
> -----------------------------------------------------------------
>
> Yet, paraffin is not dissolved by water and is extremely hydrophobic.
> So why do paraffined chains so quickly squeak and rust in the rain?
> Think about it.

I have. It's much harder to get wax to adhere to a wet metal surface
than a dry one, so I assume (speculate) that once water gets into the
link and wets the metal it starts eroding the wax film by interfering
with the replenishment process. Rain has the same effect on an oiled
chain, although it may take a while longer.

 

[Michael Press]

In article <[email protected]>,
Peter Cole <[email protected]> wrote:

> Michael Press wrote:
> > In article <[email protected]>,
> > Peter Cole <[email protected]> wrote:
> >
> >
> >>41 wrote:
> >
> >
> > [...]
> >
> >
> >>>Have you
> >>>ever rubbed paraffin, better, under some pressure, whether between
> >>>fingers or between links? It is not slippery.
> >>
> >>Have you never walked on a freshly waxed floor? Have you never waxed
> >>wooden drawers? The phenomenon you are describing is viscosity.
> >
> >
> > First what do you mean by waxed floor?
> > Coated with paraffin wax?
> > Coated with a mixture of paraffin wax and mineral oil?
> > A commercial liquid wax? What is in it?
>
> Paste floor wax -- the old-fashioned kind. What's in it? Wax and
> solvents usually.

Strictly speaking wax is an ester of glycerol and two
fatty acids. Paraffin `wax' is long chain alkanes and
rings. They are very different chemical species. For one
thing there is oxygen in wax, and none in paraffin.
Arguing from a floor coated with carnauba in low pressure
applications to a bicycle chain coated with paraffin wax
in a high pressure, high duty cycle application is not on.

> > A wood or linoleum floor coated with a film of paraffin
> > wax is not slippery.
>
> Sure it is.

So when did you coat a floor with paraffin wax?

[...]

--
Michael Press

 

[Michael Press]

In article <[email protected]>,
Peter Cole <[email protected]> wrote:

[...]

> You never used waxed dental floss?

I use it because
1. It keeps the fibers stuck together.
2. It gives body to the line.
3. It allows the floss to pass tight areas.

It is a one time application. Once used the wax is
displaced.

--
Michael Press

 

[Michael Press]

In article <[email protected]>,
Peter Cole <[email protected]> wrote:

> Sliding Property of Fe-Cu-C Sintered Materials under High
> Contact Stress and at Low Sliding Velocity
>
> "If wax is used as lubricant for impregnation instead of oil, the
> durability of the bearing can be increased, because wax has a stronger
> film intensity and about
> 2.7 times as large a coefficient of thermal expansion as that of
> lubricating oil."

What is `sintered material' mean.
What does `impregnation' mean.
How does this apply to bicycle chains?

--
Michael Press

 

[Peter Cole]

Michael Press wrote:

> Strictly speaking wax is an ester of glycerol and two
> fatty acids. Paraffin `wax' is long chain alkanes and
> rings. They are very different chemical species. For one
> thing there is oxygen in wax, and none in paraffin.
> Arguing from a floor coated with carnauba in low pressure
> applications to a bicycle chain coated with paraffin wax
> in a high pressure, high duty cycle application is not on.

You're right. The floor scenario wouldn't always show the lubrication
characteristics of wax, you need sufficient pressure to melt the wax at
the contact. The bicycle chain is a much better example.


>>>A wood or linoleum floor coated with a film of paraffin
>>>wax is not slippery.
>>
>>Sure it is.
>
>
> So when did you coat a floor with paraffin wax?

Sorry, I missed the paraffin insertion. Although I've never done it, if
I had to slide a refrigerator across a floor, I'd expect it to be much
easier with that film of paraffin.

 

[Peter Cole]

Michael Press wrote:
> In article <[email protected]>,
> Peter Cole <[email protected]> wrote:
>
> [...]
>
>
>>You never used waxed dental floss?
>
>
> I use it because
> 1. It keeps the fibers stuck together.
> 2. It gives body to the line.
> 3. It allows the floss to pass tight areas.

Right. #3 is the reason it's lubricated with wax.

 

[Peter Cole]

Michael Press wrote:
> In article <[email protected]>,
> Peter Cole <[email protected]> wrote:
>
>
>>Sliding Property of Fe-Cu-C Sintered Materials under High
>>Contact Stress and at Low Sliding Velocity
>>
>>"If wax is used as lubricant for impregnation instead of oil, the
>>durability of the bearing can be increased, because wax has a stronger
>>film intensity and about
>>2.7 times as large a coefficient of thermal expansion as that of
>>lubricating oil."
>
>
> What is `sintered material' mean.

Sintering is a process of making solids from powder (usually metal) such
that the finished part is somewhat porous.

> What does `impregnation' mean.

Filling the pores.

> How does this apply to bicycle chains?

Nothing directly, the point was the film strength was described as
stronger than gear oil, which is specially formulated for film strength.
"41" claimed wax had no film strength.

 

[HarryB]

On Fri, 03 Mar 2006 09:30:27 -0800, SMS <[email protected]>
wrote:

>HarryB wrote:
>
>> I have learned a lot from this discussion,
>
>LOL. If that were the case, you'd be switching to something that
>actually lubricated your chain.
>
>
>A great deal of intelligence can be invested in
>ignorance when the need for illusion is deep.
>
>Saul Bellow
>
Some of the things I have learned from this discussion have nothing to
do with the benefits of waxing my chains. Your post is one example.
Why does it matter to you how I "lubricate" my chains?

Harry

 

[HarryB]

On 3 Mar 2006 10:21:09 -0800, "dkahn400" <[email protected]> wrote:

>SMS wrote:
>> HarryB wrote:
>>
>> > I have learned a lot from this discussion,
>>
>> LOL. If that were the case, you'd be switching to something that
>> actually lubricated your chain.
>
>I think HarryB's argument that keeping his chain spotlessly clean is
>necessary for keeping his stoker on the tandem and his marriage intact
>is the best argument I've heard for choosing any chain preparation
>method over another, and overrides all considerations of effective
>lubrication.
>
Ahh - if marriage was only that simple ;-)

Harry

 

[41]

Peter Cole wrote:
> 41 wrote:

> > Old fashioned paste floor wax, like good automobile wax, relies on
> > carnuba (carnauba) wax, the hardest and highest melting point natural
> > wax. It is both chemically and physically very different from paraffin:

> I can find no information for the
> specific formulation of any paste floor w ax. Do you have some, or are
> you just speculating?

I knew in advance that this was the traditional ingredient and the
reason for that, and googled "carnuba" to find a specific value for the
hardness- and to also see if it was still commonly used as such.
Answer: yes, and furthermore it is used for other things far more
commonly than I would have expected (it used to be expensive). For
example, it seems we are eating a lot of it.


> >>Wax sticks well to plastic, and because it's hydrophobic will displace
> >>the water film between the board and skin.

> > Try reigning in the speculation a bit. If what you say were true, then
> > to dry the soles of my feet, I need only step on a paraffined board. Of
> > course that does not happen.
>
> Of course it does. Try rubbing a wax of your choice under water, it
> won't be slippery. If the water film remained it would be.

Today I wet my thumb, and pressed it against paraffin, either slowly or
quickly raising the pressure to as high as I could manage. I then
removed my thumb from the paraffin. In both cases it remained as wet as
before.

I then tried rubbing that wax both dry, and under water. In both cases
it was not slippery, and there was not much difference between the two,
but I would say that the wet wax was slipperier.


> >>Wax has high film strength, that's what makes it prevent floor scuffs.
> >
> >
> > Carnuba is indeed very strong (strong enough for a bicycle chain? I
> > doubt it but don't know). However, paraffin is not. Paraffin is also
> > very brittle.

I thought you were referring to hardness, since we were talking about
the solid state. Film strength usually refers to the liquid state.


> I'm sure there are many papers describing the use of wax lubricants in
> industrial applications, here's one I found quickly:

Yes, I'm sure you found that one very quickly... Would you remember the
search terms?

> <http://www.hitachi-pm.co.jp/english/seihin/tec-report/2002/pdf/tec2002_e_05.pdf>
>
> Sliding Property of F e-Cu-C Sintered Materials under High
> Contact Stress and at Low Sliding Velocity
>
> "If wax is used as lubricant for impregnation instead of oil, the
> durability of the bearing can be increased, because wax has a stronger
> film intensity and about
> 2.7 times as large a coefficient of thermal expansion as that of
> lubricating oil."

I give you an "A" for googling but only a "Gentleman's C" for reading.
The key paragraph is the following:

========================
The VG320 gear oil and the VG680 gear oil showed almost the same number
of sliding cycles before seizure; however, with the more viscous VG1500
gear oil seizure occurred at a smaller number of sliding cycles. This
is presumably because the high viscosity of the lubricating oil
prevented the oil from being sufficiently supplied to the sliding
portion, and thereby reduced the durability. Use of a hydrocarbon wax
increased the number of sliding cycles by about 1.6 times compared with
the VG320 gear oil. One reason for the good performance of the wax is
its high film strength. Factors other than film strength might have
contributed to the good performance of the wax, in view of the fact
that the increase of the viscosity of the gear oil did not improve wear
resistance. The high coefficient of thermal expansion of wax, higher
than that of gear oil as shown in Fig. 8, may be an important factor.
The coefficient of thermal expan-sion of wax is 18.8 x 10 -4 /K, or 2.7
times as large as that of lubricating oil of 7 x 10 -4 /K. Due to the
larger coefficient of thermal expansion, the amount seeping out of the
bear-ing metal as the temperature rises by friction is greater with wax
than with lubricating oil, thereby providing bet-ter lubrication.
========================================

You will note that the highest film strength oil performed the worst..
because it was too viscous. They note this problem when trying to
explain the improved performance with wax. If you read this paragraph
carefully, and then look at their figure 8, you will see that, in their
set up, the BULK temperature at the interface- not the asperity flash
temperatures- is above the melting point of the wax. They are dealing
with bulk liquid wax, with a porous reservoir of the solid wax in the
bearing, continually replenishing the interface and being replenished
by the melted wax returning to the porous bearing. This is nothing at
all like the situation with bicycle chains. See also my reply to JB
later, which should appear shortly.

> You think waxed floss wouldn't make a difference on dry teeth? I beg to
> differ. You've obviously not done much hand sewing where bee's wax is
> used to lubricate the thread. No water there.

We are straying very far from bicycle chains (porous reservoir
bearings, cloth fabric, dental floss). In fact the cloth should have a
water content similar to the relative humidity of the atmosphere.
Whatever, obviously paraffin does not make for the highest friction
pair, I am merely saying it is not slippery (like oil or ice is
slippery). But this is of no matter: as I said somewhere else, what
(should be) considered a lubricant depends on the context. Of course if
you have a very high-friction pair, then putting a medium friction pair
coating on will help. But the specifics matter: in sewing, the pressure
between fabric and thread is zilch. In dental floss, you have one
entry, a few rubs, and one exit, and I don't know that the pressure is
so high. In bicycle chains, you have very high pressures and very many
passes to squeeze any wax, solid or putatively liquid, out from the
interface, and no mechanism to recirculate it back- unless you want
porous sintered pins and links. No thanks.

As an aside, carnuba is or at least was also used as a wax on dental
floss, although paraffin may be used too, perhaps in combination. As
another aside, MP's example of waxing surfboards interested me and I
found this:

http://en.wikipedia.org/wiki/Paraffin
Uses

Candlemaking
Coatings for waxed paper or cloth.
Coating for many kinds of hard cheese, like Edam cheese.
Preparing specimens for histology.
Solid propellant for hybrid rockets
Sealing jars, cans, and bottles
In dermatology, as an emollient (moisturiser)
Surfing, for grip on surfboards as a component of surfwax.
[...]

 

[41]

Peter Cole wrote:
> 41 wrote:
> > Peter Cole wrote:
> >
> >>41 wrote:
> >>
> >>>Peter Cole wrote:
>
> >>To which paper are you referring? The only reference I can remember is
> >>to the Spicer paper:
> >> <http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf>
> >>which claimed that lubrication had no effect on chain efficiency.
> >
> >
> > That was the claim. However, if you look closely at what they found,
> > you will see, as I explained in an earlier post, that that is not the
> > case. They found no difference between an unlubricated chain and a
> > waxed (i.e., unlubricated) chain, but lubrication (oil) reduced the
> > energy losses by 17-24% as I stated above.
>
> I think you're reaching. To look at the more interesting points (higher
> loads):
>
> At 200W, 60rpm, 52x15, they measured 96.5% for no lube
> At 175W, 60rpm, 52x15, they measured 97.5% for White Lightning (wax)
>
> From the curves, the 175W extrapolated to 200W would be > 98%, so,
> using your terminology, more than 40% improvement with wax.

Thank you for taking the time to do the calculations to prove for me my
point, which was:

#this reinforces the suspicion that oiling the chain
#instead of waxing it could reduce energy losses by much more than
#17-24%, perhaps somewhere towards 40% or more.

Wow- you are making me feel like a prophet.

The proof combines your calculation with my earlier comment:
============================================================
There were several other problems with this study, which I listed in an

earlier post. The main one is that they did not validate their
cleaning
procedure by disassembling the chain and showing that no residual
grease was left. They themselves seem not to have had confidence in

their basic procedure, since to obtain what they called a "clean
chain", they used a much more thorough one: both Castrol Degreaser
and
kerosene in vigorous conditions. To get rid of the factory lube for
the
basic test, they used only Simple Green. They had a third cleaning
procedure, Simple Green and/or Castrol Degreaser, and this accounts
for
a discrepancy in values I noted earlier:

#There is a discrepancy between table 1 and table 2, where
#for the 52-15 combination @60RPM/100W, White Lightning, we see
values
# of 92.3 and 91.1 respectively.

The lower value of 91.1 is for the more thorough cleaning. This
difference of 1.2% is significant by their error margins, comes
close
to the 1.7% or so found with oil, and thus proves that their basic
procedure did not remove the factory lubricant adequately. Their
table
1 for White Lightning is in fact for factory grease plus White
Lightning.
==============================================================



[

 

[41]

[email protected] wrote:

> I'll also point out that "41" absolutely rejected my first test showing
> decreased friction in metal-to-metal contact. He claimed this was
> because it was not the exact, precise composition he preferred to
> discuss. IOW, it was not pure paraffin. Yet he's willing to use, for
> his purpose, data from White Lightning, which is also not pure
> paraffin!

Would you stop fabricating claims and attributing them to me. In fact I
declined comment on your first test because you mixed your paraffin
with oil. To be precise, the entire contents of my reply to your first
experiment were:
=============================================================
[email protected] wrote:
> or rather, my mix of paraffin with
> about 5% oil blended in.

You have flunked another literacy test:

As I said, paraffin with oil in it seems to me to be some sort of
ersatz grease and my comments are not meant to have any bearing on
it.
=============================================================

To complete the story: White Lightning is sold as being oil-free.


>While I haven't used White Lightning, I've used another
> wax-in-solvent commercial product, and I don't think I'm alone in
> finding those much less effective than heated paraffin-oil mixes.

Well. Isn't that interesting*. I wonder why?


> Overall, "41" seems to come up wi th separate and changing objections to
> every piece of data that's provided.

Nice try. In fact, I specified the parameters which your experiments
flouted BEFORE you did them, and repeatedly.

"Overall", I seriously find that you have a serious reading
comprehension problem, and that you should strive to correct it on a
priority basis.


---------------------------------------------------------------------------------------------------------------------------------
*Correction to a previous comment of mine: earlier I said that slack
paraffin is 2-3% oil (perhaps I also said, or more, I don't recall). In
fact, slack paraffin may be up to 50% oil:
<http://tinyurl.com/oplzg>#

 

[41]

Peter Cole wrote:
> 41 wrote:

> Since soaking a chain in liquid wax (or the equivalent) deposits a fair
> amount of wax in the various clearances in the chain, I would assume
> that normal link articulation would replenish the film just from
> rotational contact on those reservoirs. Speculation on my part, but I
> don't know how the proponents of the technique would get the claimed
> durability otherwise.

A good example of replenishment from a reservoir is the porous sintered
bearing discussed earlier. In that example, the bulk temperature melted
the wax to a liquid state. I find no comparable mechanism in bicycle
chains and do not see how wax could be replenished. See also my reply
to JB which should appear momentarily. I believe the claimed durability
is simply from the fact that their chains are clean.

> > Yet, paraffin is not dissolved by water and is extremely hydrophobic.
> > So why do paraffined chains so quickly squeak and rust in the rain?
> > Think about it.
>
> I have. It's much harder to get wax to adhere to a wet metal surface
> than a dry one, so I assume (speculate) that once water gets into the
> link and wets the metal it starts eroding the wax film by interfering
> with the replenishment process.

If this were the case, and the reservoir mechanism is as you describe,
would not the problem be solved simply by drying the chain, and then
presto you could use it again without further relubrication?n

 

[41]

Peter Cole wrote:

> Although I've never done it, if
> I had to slide a refrigerator across a floor, I'd expect it to be much
> easier with that film of paraffin.

So would I. The contact area is large and there is only one slide
anyway. But consider: would it be easier to slide with a film of
grease? In fact, probably not, because you wouldn't even be able to
stand up to push or pull on the fridge. Likewise, consider a
solid-melting lubricant like ice: think of how much easier it would be
to slide that fridge around- if you had skates to push yourself with.

Why don't you need skates on waxed floors, but you do need something
comparable on ice or on greased floors?

 

[41]

[email protected] wrote:
> George King writes:

> # What is or is not a lubricant obviously depends upon context,
> # meaning the friction pair and the pressure. For example, sand is
> # not generally considered a lubricant, and I expect yo u wouldn't have
> # gone after me if I had said SAND IS NOT A LUBRICANT, but it will
> # reduce friction if interposed between the adhesive sides of two
> # pieces of Scotch tape, or for that matter, between a shoe and a dry
> # sidewalk- or a tire and sa me. We are talking here about bicycle
> # chains. Coefficients of friction vary wildly depending on the
> # precise context
>
> Hold it! As I said, this is delving into tribology and from what I
> read here tribological definitions are missing. The c oncept of "third
> body lubricants" includes materials like sand. Although abrasive,
> such particles work as friction reducers both in the sandy road
> surface and for instance, in hard disk storage mediu m in which wear
> debris reduces friction between transducer sliders and disk.

In most fields there are lumpers and splitters. The splitters sometimes
come up with uncomfortably narrow definitions ("glass is not a solid
because it is not crystalline") while lumpers may come up with
uncomfortably wide ones ("sand is a lubricant"). Sometimes the gap is
bridged by judicious use of the prefix "quasi". If I empty a bag of
ball bearings on the road, have I lubricated it? Whether ball bearings
or sand, if I want to calculate the friction and wear characteris tics
induced by my act of lubrication, I have to consider whether or not the
interface between my (third body) lubricant and the relevant surfaces
is... lubricated. In other words, whether or not my lubricant is
lubricated! I am not a fan of such contortions and would need a
compelling reason to accept one.

My own view is that, in order to avoid idiosyncracies, classes should
be based on the laws of the system. In other words, systems which share
the same broad laws should be considered to belong to the same broad
family. This is the concept of a natural kind. For example, the gas
laws for gases. Are there broad families of tribological equations
(laws) satisfied by both third-body lubricants, say for example sand,
and all other lubricants? If so then I would be happier to consider
sand as a lubricant, third-body or otherwise.


> You might consider how two solid materials slide o n one another. In
> all cases, one or both materials flow at flash-points if there is no
> separating lubricant. Asperity contacts cause temperatures many times
> higher than the apparent bulk temperature and these serve to cause
> local melting.

Some amateur remarks:
I thought that, given the wide variety of calculated asperity
temperatures, according to the various mode ls and assumptions, and
given the difficulty of experimentally verifying those temperatures,
that this mechanism, although proposed some half-century ago, and
having what could be described as most-favoured theory status, still
was somewhat unresolved, ce rtainly as a blanket statement for all
material pairs under all conditions.
<http://tinyurl.com/rrlxt> (PDF)
Besides, could not the sliding, although perhaps you would then not
call it sliding, be accomplished by brittle fracture of asperities and
accumu lation of wax dust. Paraffin is brittle.

In any case, I wonder about the following. If we are considering
paraffin-paraffin contact, paraffin is a weak substance. As an
example, yield pressure appears in the numerator of the expression for
asperity tem perature in Archard's equations, and with hard materials
having yield pressures in the gigapascals generating temperatures in
the hundreds of degrees, what is going to happen with something as weak
as paraffin? On the other hand, if we are considering the steel
asperities in the chain, then (a) since the contact and durations are
so local, these must be continual to keep the paraffin liquid; (b)
would not the temperatures would be high enough to locally carbonize
the paraffin and locally melt the steel; a nd (c) in any of these
circumstances, the paraffin wouldn't be lubricating anyway.

Nevertheless, as I replied to someone else, suppose it really were the
case that liquid paraffin is being generated and lubricating the
interface under great pressure. If so, it will be pushed out of the
interface, and then no longer be subject to the movement and friction
that melted it. So, it can not replenish the surface again. The system
is not like a porous sintered bearing that someone else had proposed
before, whi ch acts as a reservoir for the wax, continually
replenishing and being replenished. Nor is it like friction with ice,
where again there is a reservoir to continually relubricate the
surface. There may be a lot of wax around a waxed bicycle chain, butI
see no mechanism to allow it to recirculate with the contact surface.