# Gentle Titanium warning.......



## Anglepoise (Aug 18, 2006)

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I just experienced my first case of Titanium galling.

For those not familiar with the term, galling is when the threads , male and female, lock together ( cold weld) and do not easily undo without damage. This effect is more prevelant when both parts are the same material, in my case both Ti.

I found out later that this happens more often when both parts are clean and new. In my case, I was 'fitting' two threads that had just been cut on the lathe.
Both parts had been finished, de burred and were spotlessly clean with no lube residue. I was playing around with the fit, and felt that they were a touch tight. I put a bit of hand pressure on while turning and then the threads just 'locked up'. Luckily these were bare parts and I was able to soak the union in penetrating oil and eventually get the two parts apart with little damage.

I have not read of any problems with finished Ti lights. However until recently there were very few Ti lights out there.

I am lead to believe that the solution is to keep a lubricant on the threads.
Any lube is better than none. Galling needs two clean surfaces and pressure.

There has been lots of 'lube' threads and my intention was not to get into a
"I use this lube and its great" discussion. The key here I think is to make sure that there is adequate lube of some description on Ti threads, particularly those static threads that only get unscrewed once in a while.


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## Lurveleven (Aug 18, 2006)

Deja vu! Did you post this same post earlier today, I can swear I read it earlier today.:thinking: 

I'm wondering if the same can happen to a light in use if you not relube it as the lube disappears with use?

Sigbjoern


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## Led-Ed (Aug 18, 2006)

Stainless steel does the same thing -beware.


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## Anglepoise (Aug 18, 2006)

Lurveleven said:


> Deja vu! Did you post this same post earlier today, I can swear I read it earlier today.:thinking:
> 
> Sigbjoern




Yes....I put it in the wrong classification and deleted it.


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## McGizmo (Aug 18, 2006)

Good caution there! I have also had stainless steel and raw Al gall on me (or in the case of Al, it may have been a chip or burr that got jammed and then pressed into the soft metal to the point I couldn't break it free.)


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## JohnK (Aug 18, 2006)

The earlier stainless steel handguns/rifles had this problem.

They (partially) solved it by using differing stainless steel alloys.


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## BigHonu (Aug 18, 2006)

Ti watch cases usually have stainless screw in backs to eliminate this problem as well.


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## MoonRise (Aug 18, 2006)

Yup, galling some parts together is un-fun.

Had it happen with some stainless hardware. IIRC, it was either 3/8 or 1/2 nuts-n-bolts. Most unfun as the parts galled before they snugged up. I -think- we (yes, it took more than one person) finally got the galled parts apart with some big breaker bars. Emphasis on 'breaker' there. Tossed the nut-n-bolt out, and went and got some NeverSeize and made sure to use it on the rest of the stainless hardware!

Clean, smooth, and same alloy is the worst case for galling. Different alloys between the two parts helps to reduce the risk. Lube helps to reduce the risk. It doesn't happen to just threaded parts, it could be a problem with ANY parts in intimate contact where the metals press/touch just right (or wrong) and basically weld themselves together. Sometimes the loading will overcome the galling and the parts will be 'free' again, but will have transferred some metal from one part to the other to the detriment of dimensions and smooth surfaces.

Stainless, titanium, aluminum, niobium, and other metals are listed as most prone to galling.

IIRC, some early stainless steel semi-auto pistols also originally had issues with galling of the slides and frames.

Yup, galling is not fun.


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## modamag (Aug 18, 2006)

TiN or TiCN coating should help prevent galling.

I thought that this would not happen to most of our light since it's only class II theads (some clearance).

Anglepoise, could you show us the picture of the "minimal damage". Could the root cause be that the threads on your is just too perfect?


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## aosty (Aug 18, 2006)

Yup - use grease or anti-seize compound on the threads.


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## PEU (Aug 18, 2006)

And allow a little of play when you machine the parts, so the fit is not so tight. 
I had the problem with bare AL, it oxidized and the oxide became glue 


Pablo


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## Anglepoise (Aug 18, 2006)

modamag said:


> TiN or TiCN coating should help prevent galling.
> 
> I thought that this would not happen to most of our light since it's only class II theads (some clearance).
> 
> Anglepoise, could you show us the picture of the "minimal damage". Could the root cause be that the threads on your is just too perfect?




Sorry.....No pics. It was not till quite a while after the event that I realized that
it was galling. The 'minimal damage' was tearing on the threads and they cleaned up well, working the threads back and worth with metal polish. I think it was the fact that both parts had been de greased and were clean, and yes the threads were on the tight side and that did not help. I think the key is 'always lube on the threads'.


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## Supernam (Aug 18, 2006)

Sparkplug anti-seize compound might be a good idea.


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## tvodrd (Aug 18, 2006)

If things are fitted too close, feces has an increased opportunity for occurring! 20 years ago surplus, stainless steel aerospace fasteners were frequently encountered with silver plating to reduce galling. If you _have_ to work at near net fits, initial assembly with some micronized MOS2 will usually preclude feces! OTOH, some thread clearance makes momentary switching possible with a twisty.  Finding houses that can hold those kind of tolearnces is no small issue!

Larry


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## greenlight (Aug 19, 2006)

Anyone use galling as a benefit or feature to bind 2 pieces?


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## HarryN (Jul 15, 2014)

Hi, I realize that I am reviving an old thread, but it is a Ti + galling question, which sort of fits this thread.

I have an application for an acme screw thread and nut. Commonly, these are stainless screws + a bronze nut, at least in part to avoid galling. For weight and corrosion resistance reasons, I am considering to make at least one of them from Ti and the other from ? 

How hard can the "other" be to avoid galling ? I wish I could count on the surface to always be oil coated, but that does not seem to be the case.

Thanks

Harry


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## precisionworks (Jul 16, 2014)

You may want to consider titanium for both parts & have at least one (preferably both) anodized with an engineered hardcoat like Ti Fin 400 - Brown Fluffy Oxide - (meets AMS2487 standards) or TIODIZE Type IV

 http://www.titaniumfinishing.com/page02.html 
http://www.tiodize.com/anodizing.html 
There are other companies that offer a similar thick engineered hard ano ... as differentiated from a color ano that's nanometer thin. Small quantities of parts can be done by these companies but there's a minimum charge if you do two or two hundred.



> How hard can the "other" be to avoid galling ?


Way out of my lane on this but IIRC it isn't a question of part hardness but rather one of adhesion due to the oxide surface. Lots of info on this, here's a short read from the Society of Tribologists & Lubrication Engineers: http://www.stle.org/resources/articledetails.aspx?did=1631


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## cyclesport (Jul 16, 2014)

FWIW HarryN...most higher end bike (bicycle) shops carry small tubes of anti-seize compound *(google "Finish Line Ti-Prep" brand) useful for a variety of app's with Ti on Ti, or Ti on any dissimilar metal, threaded or clamped parts. Inexpensive, stays put for a long time, and works great!


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## HarryN (Jul 16, 2014)

Thank you for the ideas, leads, etc. I am particularly interested in approaches that do not require lubrication. If I had control of the situation that would be different, but it is for a customer application. It is an interesting, but complex to use material system.

Thanks

Harry


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## precisionworks (Jul 16, 2014)

HarryN said:


> I am particularly interested in approaches that do not require lubrication.


The engineered ano coats provide an electrically-insulating, non-powdery anodic coating on titanium and titanium alloys. This process has been used typically to increase resistance to galvanic and high temperature corrosion and voltage breakdown and to form a receptive base for the application of dry lubricants. 

Titanium Finishing Co will follow the ano coat with a solid film lubricant on request. TIODIZE Type IV is Type II finished with TIOLON X40 PTFE impregnated into the surface to provide low friction and anti-galling for longer life at higher loads. Most all the engineered ano finishers offer both the ano coat & the dry film coat.


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## HarryN (Jul 21, 2014)

Thank you for the great advise - It is appreciated.


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## precisionworks (Jul 22, 2014)

Certainly. Also, if you'll provide the mechanical specifics for the application they'll make sure the ano & dry lube are suitable or suggest alternatives.


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## brickbat (Jul 22, 2014)

HarryN said:


> ...I have an application for an acme screw thread and nut. Commonly, these are stainless screws + a bronze nut, at least in part to avoid galling. For weight and corrosion resistance reasons, I am considering to make at least one of them from Ti and the other from ?



Without knowing your application, I don't know if this makes any sense, but might a slippery plastic, like Delrin work?


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## HarryN (Jan 6, 2015)

brickbat said:


> Without knowing your application, I don't know if this makes any sense, but might a slippery plastic, like Delrin work?



Hi, Thanks for the replies (sorry for the delay, I have been off-line for a while). Coatings might well be the right solution. I have been hesitant to go down that path because the screw will be used in a salty and gritty environment, but it might still be the right method.


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## gadget_lover (Jan 7, 2015)

brickbat said:


> Without knowing your application, I don't know if this makes any sense, but might a slippery plastic, like Delrin work?



For anyone looking to do that... check out the technique suggested by Evan over on home shop machinists.

http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts-the-easy-way

Dan


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## HarryN (Jan 20, 2015)

Thanks for the link Dan.


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