Tribology 2

[learningspecific]

Can anyone please explain in detail what the concept of "seizure" in tribology is?

Atleast please specify some books or papers which will clear the concept.

 

[racookpe1978]

Robt will not repeat the sarcastic definition that follows from his old Tribology dictionary:

"When one Indian band finds a second tribe's female member unaccompanied in the wilderness, the first command issued is usually a quickly whispered "Seize 'er!" 8<)

(Have you tried Google? What mechanical engineering or machining references do you have?)

 

[learningspecific]

Tried googling but could not figure out anything good. Tell me the name and I can get it.

 

[learningspecific]

people no jokes please..

 

[racookpe1978]

You're not trying effectively. I get 26,000 results from Google using "Tribology, material, seizure" ... Including this one as a single practical example of people trying to solve a single shaft seizure problem between aluminum and soft steel:

http://www.eng-tips.com/viewthread.cfm?qid=189628&page=2

Hint: Your question cannot be answered because we don't know what problem you are trying to solve. For example, this book

http://books.google.com/books/about/Mechanical_tribology.html?id=Vk_cULgsCucC

needs about 496 pages to define tribology.

 

[unclesyd]

As posted in your OP, seizure is hard to define without setting some conditions as it can be described as won't turn, won't slide, won't go, etc.

Checkout this website. Seizure is referenced normally as the results of tribological events that happens prior to the actual end result.

http://www.tribology-abc.com/

 

[learningspecific]

I just need to understand the concept of what seizure exactly is and how it occurs. I know that you get a number of results when you search the word, but if you notice apart from the first 2 or 3 , all results just contain the word seizure. Nothing is explained about it. As for the book, only the name is given in google books, you cant actually read it. As google books, as you must be knowing has very few books available for full view, and unfortunately none of these books are available for full preview.

 

[Tmoose]

unclesyd's description (not definition) "won't turn, won't slide, won't go" works for me.

An engine in a Chevy pickup truck might metamorph from running just fine to not running, with the crankshaft held fast by unseen forces. Most would say the engine had "siezed".

Lack of oil might have caused local temperatures so high the various rod or main bearing inserts became welded to the crankshaft. If removed they might look similar to page 15/20 here.

http://www.engineparts.com/publications/CL77-3-402.pdf

Or, upon disassembly the former aircleaner nut might be found to embedded in the piston.

I'm guessing tribologically speaking sliding surfaces that "welded" together might be intended.

 

[TVP]

learningspecific,

The link to Google Books provided by racookpe1978 does have a preview, which allows for viewing almost all of the 28 pages where seizure occurs. One definition that is given is "a stopping of the mechanism as a result of high friction localized deep in the surface layer, which causes its permanent damage". It is often used in conjunction with the term scuffing. There is no definition of seizure in ASTM G40, AGMA 912-A04, or AGMA 1010-E95.

The following definition of seizure appears in ASM HANDBOOK Volume 18 Friction, Lubrication, and Wear Technology:

The stopping of relative motion as the result of interfacial friction. Notes: Seizure may be accompanied by gross surface welding. The term is sometimes used to denote scuffing (Ref 1m).

Ref 1 is Glossary of Terms and Definitions in the Field of Friction, Wear and Lubrication (Tribology), Research Group on Wear of Engineering Materials, Organisation for Economic Cooperation and Development (OECD), Paris, 1969.

 

[ivymike]

I would say that you can have scuffing without siezure, and vice versa. In the case of pistons, it's often the case that scuffing naturally progresses into a full-blown siezure. Scuffing shows up as a region of abrasion and material transfer with visible scarring. Siezure is simply "it don't go up n down no more."

 

[Clyde38]

Try the Tribology forum

http://www.eng-tips.com/threadminder.cfm?pid=342

[link

http://www.linkedin.com/in/clydehancock

]

[/url]

 

[unclesyd]

I just remembered a description given to me by my father when we had a bearing seize on a table saw, "Stopped Short Never to go Again".
Adding a little to my my original post.
As stated seizure is the end result of one or several events and it can be caused by many things and each set of conditions that cause the stoppage will have a different mode of tying the two metals togather.
A few things that can cause seizure of metals failure of lubrication, different coefficients of thermal expansion, metal growth, chemical reaction. an many others. Metals will normally weld togather but this necessary for seizure to occur. A gas engine sits idle and the piston seizes up, this is normally a result of one or two things. the Al piston corrodes and mechanically locks the ring in the bore or the ring rusting and seizing by the same process. This situation is extremely hard to break apart, but is not not welded. If COE of two metals involved, say in a shrink fit where there was not enough heat/cooling applied so during assembly the parts seize. gain there is no welding of the metals and the problem can be overcome with very little damage to either component.

You have various definitions of seizure but each has to be described in the context of whats was happening at the time.

 

[SomptingGuy]

In my experience, "seizure" is when the twist grip stops working and you find yourself decelerating at a worrying rate. Or maybe that piston just scuffed as its crown crumbled? I've kept it as a trophy.

- Steve

 

[Ron]

Tribology is about effective lubrication and the analysis of such to achieve the desired result. Seizure is a failure of the concept of lubrication (by stoppage or excessive friction from lack of lubrication), in which tribology then becomes a failure analysis mode to determine the probable cause of seizure.

 

[racookpe1978]

I've seen Seizure most often happen with very high tensile bolts holding extremely high tensions for long times at modestly high temp's (1200 - 1400 degrees), stretched by preload heat and high torque on turbine head closure, but unmoving.

The "seizure" is the state of being "galled" - threads welded over time between two surfaces under high pressure.

 

[btrueblood]

racookpe,

Your described situation I have encountered before also, but would call the phenomena diffusion bonding, or solid welding. Galling I believe is more due to sliding contact (motion between two surfaces), and the welding occurs nearly instantaneously. I know it's subject to how you learnt it, but apparently ASTM has said so too:

http://en.wikipedia.org/wiki/Galling

FWIW, we had good sucess in a lot of places where diffusion bonding was occurring on fasteners, by applying a coating of boron nitride (as spray-on powder) prior to assembly.

 

[ornerynorsk]

Seizure may also be temporary, purely thermal in nature, without mechanical damage to the surfaces. Repeated events will likely digress into damage, however.

Vacuum lock or liquid lock may also imitate seizure.

I'd have to agree that the book recookpe suggested, although not light reading, is a good reference to begin understanding. There are perhaps a dozen good publications on the subject found with just a cursory search.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.