Ti threads - to lube or not to lube?

[TranquillityBase]

No I haven't. I wonder if it is a new addition to the lineup. As I recall, once I figured out which was thinest of the oils and greases, that is what I went for. Perhaps the distributor I dealt with didn't have the 100 or 200. :shrug:

Don, I sent you a link to a PDF for Dupont's Krytox offerings.

 

[McGizmo]

Thanks Scott,
I received it. It would be interesting to get a hold of some of the 200 grease and see if it would perform reasonably without need of mixing in some oil. When I eventually run out of the 101/201 batch I have, I will see if I can find a source for it and give it a try. The 201, by itself just didn't cut it for me.

 

[precisionworks]

I saw this on a site today:

The coefficient of friction of commercially pure titanium is given in the range .30 -.34, with lower figures in the range .25 - .30 for titanium alloys. Practical tests can indicate much higher figures, into the range .8 - .9 for rubbing contact of untreated surfaces without lubrication. Three fundamental factors combine to give titanium its high coefficient of friction and cause the poor tribological behaviour of the metal. The first arises from titanium's atomic structure, and this can be marginally improved by bulk or surface alloying to form a harder and more wear resistant structure.

The second factor comes from the crystal structure of titanium. Modification by alloying occurs naturally in the range of alloys, which to various extents offer slightly better resistance to wear as compared to pure titanium.

The third problem is the relatively low tensile and shear strength of the titanium oxide film. When adhesive bonding occurs in rubbing contact with adjacent titanium or other metal surfaces, the fracture occurs in the oxide rather than at the interface, resulting in large amounts of material transfer, galling, and high wear rates. Improvement of strength and hardness by bulk alloying offers some improvement, but this problem and indeed the other two factors above can also be overcome by removing the titanium entirely from the tribo-system by coating with another material, metallic or otherwise.

The combination of dry film lubricants with anodized and other surface treatments frequently provides the best longer term solution to adhesive wear of titanium.

Source:http://www.azom.com/details.asp?ArticleID=2617

 

[yaesumofo]

It sounds like plating the threads with some very hard wear resistant material would work wonders. Has anybody plated titanium with chrome? IMHO the problem with "anodized titanium is that it doesn't wear that well. It certainly doesn't stick to the base metal as well as aluminum anodizing does to aluminum. The concept of masking parts and plating the threads is interesting. It is also a lot of work and those machined parts which would be plated would have to be machined with this in mind.
I think I will stick to my current solution until I see something more practical come around.
Yaesumofo

I saw this on a site today:

The coefficient of friction of commercially pure titanium is given in the range .30 -.34, with lower figures in the range .25 - .30 for titanium alloys. Practical tests can indicate much higher figures, into the range .8 - .9 for rubbing contact of untreated surfaces without lubrication. Three fundamental factors combine to give titanium its high coefficient of friction and cause the poor tribological behaviour of the metal. The first arises from titanium's atomic structure, and this can be marginally improved by bulk or surface alloying to form a harder and more wear resistant structure.

The second factor comes from the crystal structure of titanium. Modification by alloying occurs naturally in the range of alloys, which to various extents offer slightly better resistance to wear as compared to pure titanium.

The third problem is the relatively low tensile and shear strength of the titanium oxide film. When adhesive bonding occurs in rubbing contact with adjacent titanium or other metal surfaces, the fracture occurs in the oxide rather than at the interface, resulting in large amounts of material transfer, galling, and high wear rates. Improvement of strength and hardness by bulk alloying offers some improvement, but this problem and indeed the other two factors above can also be overcome by removing the titanium entirely from the tribosystem by coating with another material, metallic or otherwise.

The combination of dry film lubricants with anodized and other surface treatments frequently provides the best longer term solution to adhesive wear of titanium.

Source:http://www.azom.com/details.asp?ArticleID=2617

 

[McGizmo]

It sounds like plating the threads with some very hard wear resistant material would work wonders. Has anybody plated titanium with chrome? IMHO the problem with "anodized titanium is that it doesn't wear that well. It certainly doesn't stick to the base metal as well as aluminum anodizing does to aluminum. The concept of masking parts and plating the threads is interesting. It is also a lot of work and those machined parts which would be plated would have to be machined with this in mind.
I think I will stick to my current solution until I see something more practical come around.
Yaesumofo

The Ti anodize is a clear oxide film that has been discussed numerous time here on the forum. you get different colors by light interference reflecting off both the surface of the oxide as well as the parent material underneath (refractive metals do this). The oxide film is however quite thin and according to the info from Precisionworks, not that well bonded to the parent material, relatively speaking. I italicized relative because we don't know the magnitude of forces being considered in the case of galling and friction. The threads on these lights are not being subjected to the forces which typically bring about serious problems, IMHO. Certainly any interference in the thread itself or resulting from contamination of any debris can become a problem.

I have a few Ti lights that have been plated with the TiCN and diamond film thanks to ModaMag. I suspect that these lights are better suited for friction reduction. I would guess that having one part plated and the other not would also help as you would have a relatively soft part mated to a relative hard part. I also suspect that in the case of the 6-4 alloy that one part could be heat treated driving up its hardness relative to the not treated part. However, I think such schemes are serious overkill, in our applications. It has been my experience that once the threads break in and have a reasonable amount of good lube on them, there is really no issue of significance.

 

[precisionworks]

I have a few Ti lights that have been plated with the TiCN and diamond film

Now you have me thinking about having the female threads plated with hard chrome ... the only problem is that my plating shop has a minimum charge of $90 + tax, so it makes it high priced for only one ... ten would cost (if I figured correctly) about $290, or $29 each. Hard chrome wears well, with hardness of HRc 68-72.

 

[McGizmo]

Now you have me thinking about having the female threads plated with hard chrome ... the only problem is that my plating shop has a minimum charge of $90 + tax, so it makes it high priced for only one ... ten would cost (if I figured correctly) about $290, or $29 each. Hard chrome wears well, with hardness of HRc 68-72.

I believe hard chrome has more build than ornamental chrome? I recall that on ornamental chrome there was a tendency to "tree" in the threads which caused some nasty interference for me on some PD's that were chromed. The machine shop uses go/ no-go gages on the threads but adding film thickness to them may also add to any problem of ease in rotation. You might want to lap the threads first with some diamond compound prior to any plating.

 

[precisionworks]

I stopped by the plating shop yesterday & showed the owner the PD tube, less piston, stating that the reason for plating was primarily to coat the threads. He flatly said HC will not work ... they primarily do cylinder ODs & smooth bore IDs, and the plating will be heavier on the crests of the threads than on the roots. He suggested Electroless Nickel as the most likely approach.

I believe hard chrome has more build than ornamental chrome?

That it does - I've built up nearly .100" on worn shafting, but it has to be done in stages. They first turn the shaft smooth to remove any surface defects, then add .050" of HC & wet grind about .005 off to 'flatten' the surface - it starts to get peaks & valleys in greater thickness. Then another .050" is added followed by another wet grind. The shop I use can grind to .0001 (or better) if needed, and hold finish to single digit levels, which is nice for Torrington bearings that use the shaft as the inner race.

Great stuff for buildup, not so good for threads:scowl:

 

[precisionworks]

All this talk about Krytox caused me to call Miller-Stephenson Chemical Co. (industrial distributor). They were kind enough to send an aerosol can of Krytox Fluorinated Synthetic Lubricant (MS-1106). The active ingredient is Krytox GPL Oil, in an instant evaporating carrier. Spraying a little onto the palm of my hand gave an instant cold feeling (evaporating carrier) with only a slight oily deposit ... just enough to notice.

Krytox GPL oils come in grades 100/101/102/103/104/105/106/107. Uncertain which oil this aerosol contains, I phoned tech help at M-S Chemical. They stated GPL 106, which is next to the heaviest/thickest GPL available. It is ISO VG220, about the same as SAE-50 motor oil. My guess would have been much thinner, like GPL-100 or GPL-101 (ISO VG5 or ISO VG7)

The scientist at M-S Chemical said he'd tried all the GPL grades & his testing showed the 106 to give the best results over a wide temperature range. With that, I recleaned the threads on the LS20, removed the O-ring & cleaned the O-ring groove, sprayed the O-ring groove, threads, and piston bore with Krytox Aerosol, and assembled. Both the twist action & the piston push required little effort. There was enough of the teflon grease in the O-ring groove that it probably caused the O-ring to drag as the head was twisted.

Krytox info at:
http://www2.dupont.com/Lubricants/en_US/assets/downloads/H58510_1.pdf

 

[Edwood]

Actually, Krytox is specifically made for rubber like in O-Rings. Well, at least the grease is.

As for expensive car wax, that would be 100% Carnuba wax. It will be a block of soft wax, just rub some on your fingers, and then rub them on the O-rings and threads.

-Ed

 

[precisionworks]

I'm still experimenting with this:thinking:

Most of the literature suggests that Ti-on-Ti sliding contact is more prone to galling than any other metal. The best solution, according to many different articles, is to coat one Ti surface so there is no Ti-Ti contact. A few specialty coating companies offer engineered anodizing, as opposed to color anodizing. Engineered anodizing provides a thick film (around .001") that can be used as is, or that can form a base for solid film lubricant.

Why haven't my lights been sent for anodizing? The colors of the engineered anodizing are ... not the most attractive in the world. Color #1 is called [FONT=Arial, Helvetica, sans-serif]Lustreless Gray, while color #2 is called [/FONT][FONT=Arial, Helvetica, sans-serif]Brown (Fluffy) Oxide. IMO, neither one has a great deal of eye appeal.

Color 1 meets [/FONT][FONT=Arial, Helvetica, sans-serif]AMS2488, Type II, specifications.

Color 2 meets [/FONT][FONT=Arial, Helvetica, sans-serif]AMS2487 specs.[/FONT]

 

[nbp]

I can't believe I found a thread with my exact question! I had used some of the reel lube that I use on all my lights the other day on my Haiku (it is a PTFE based lube, presumably re-branded Superlube, thus the reason I was happy to find this thread). And when I went to take it apart last night it was much harder to break the head loose and the o-ring kinda came off with it. I was pretty surprised as I have not had a problem with this lube before, even on a MiNi Ti, which is obviously a twisty. It seems there is no good answer here either.

I then found some of Henry's magic orange lube that he gave in those little ziploc baggies and put that on. I am waiting to see how that stuff works out. I will update when I have some results. :shrug:

 

[fyrstormer]

Magic orange lube? Is it copper colored? If so, it's a copper-based anti-sieze compound, good for keeping the threads from sticking together but not so good for preventing wear over repeated cycling.

I developed my own lube for my collection of Gizmos and other titanium lights. It's made from the stickiest petroleum oil I can find, doped with molybdenum disulfide, partially-gelled with Teflon powder. I call it TiTi Twister. I have yet to find anything better, though it does have a bit of a sulfur smell when the threads are exposed, and the stickiness of the base oil tends to make it creep out of the threads very very slowly. Smell and aggressiveness aside, I've been using it for a couple years now and the threads on my PD lights are actually polishing themselves as though they were made of steel instead of titanium. I'm rather amazed.

 

[jumpstat]

Don,

What oil/grease did my Haiku came with?

I tried nyogel and Krytox but I was regretting doing so as the o-ring now is somewhat sticking to the Haiku head when removed from the body.

 

[nbp]

Henry's magic lube didn't work. I still had the same problem that jumpstat described above. The lube went gummy, the head got kinda stiff to turn and the o-ring stuck to the head. Did the light come with the concoction Don talked about above or what is he using these days? It seemed to work better than what I have tried. Right now, I just cleaned the threads and ring off as well as I could and let it go naked. It's probably better than the lube fiasco I created.

 

[Anglepoise]

On twisty's, one and a half turns of Teflon Tape around the male threads works wonders and has no stiction.

...........and where 'O' rings are involved, I have found 100% Dupont Teflon Bearing grease to be fantastic

 

[nbp]

How do you get the tape off when it starts to shred and disintegrate? You can't really wipe it off like lube.

 

[Anglepoise]

I have never had a problem replacing the tape when worn. Also there are different thicknesses. I use the pink and it holds up very well.

 

[fyrstormer]

I've never had trouble with SS Krytox 50/50 per se, but I personally prefer a petroleum-based lube because they handle metal-on-metal contact better than most everything else. However, the stock O-ring is damaged by petrochemicals and has to be replaced with silicone or nitrile.

Krytox works just fine if you're not going to be constantly disassembling and reassembling the light, though.

 

[McGizmo]

I use Krytox but other lubes are preferred by others and what ever floats your boat. As Fyrstormer states, the EPDM is not compatible with petroleum based lubes.