Tell me about Film Strength and bonding molecules

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1,203
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Oregon
If Film strength is not related to oil viscosity. And is More or less determined by how well the molecules bonds together. Exactly what bonds the molecules together??
 
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Millbrae, CA
Classic film strenght of a lubricant is increased mostly buy increasing oil viscosity or using oiliness or other polar additives that have a affinity for metal. they will lay down a layer with the most polar end "stuck" to the metal bearing the other less polar head floats up on end lets say that allows a otherwise un additzed oil to carry a higher load. The polar additves acts like a anti wipe lube suporting the load. There are other way to do this with other type of additives but that gives a idea. bruce
 
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n.j.
HI BRUCE: if money was no object what engine oil would you use in your own vehicles, please name the brand thanks.
 
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SA
i'm sorry you wrong, oil Film Strength does NOT RELY ON THICKNESS!!! RP's 0w7 Race oils. protect more than ANY other oil when used in the correct application, they almost thinner than water, and you say they reliant on VI... You need to get rid of the theory of thicker is better my friend...
 

Hirev

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1,203
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quote:
i'm sorry you wrong, oil Film Strength does NOT RELY ON THICKNESS!!! RP's 0w7 Race oils. protect more than ANY other oil when used in the correct application, they almost thinner than water, and you say they reliant on VI... You need to get rid of the theory of thicker is better my friend...
You know some where in an article I read something along the lines of. Not to confuse film strength with oil viscosity. Film strength is determined by how the bonds between the molecules hold together under extreme heat and pressure. And that the thickness of an oil is determined by the length of the molecular chain. If I understand it right, the film thickness goes up with viscosity but not necessarily the film strength.
 
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SA
But, the more you increase the viscosity, the more power the engine must use to move that oil, like compare 20w50 to 5w30, thicker oil takes longer and harder to move around than thinner.. Think like this: The amount of energy stirring syrup and water...Syrup is going to be a lot harder with more effort to move than water... Just a thought
 
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7,409
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So what are the dimensions of "Film strength". Viscosity? Well that easy. It's the property of a fluid such that the force required to move a unit surface area past a parallel surface a certain distance per unit time when said fluid exist as a film of unit distance thickness between the surfaces. However, looking in a Lubrication and Oil Analysis Dictionary, we find this definition of Film Strength - property of a lubricant that acts to prevent scuffing or scoring of metal parts. OK, what is scuffing? Scuffing - abnormal engine wear due to localized welding and fracture. It can be prevented through the use of antiwear, extreme-pressure and friction modifier additives. So I guess we need to add molecular forces into the mix. So looks like it's more than just viscosity. Also, viscosity is dependent on temperature, pressure, shearing conditions and maybe others. Given the above, Film Strength looks to be a very general term that is kinda' meaningless unless many of the other parameters involved are specified and are put into context.
 
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23,591
quote:
Given the above, Film Strength looks to be a very general term that is kinda' meaningless unless many of the other parameters involved are specified and are put into context.
Who better to specify those parameters and put them into context than you? Just telling us film strenght isn't just this or that, why not be a little bit more concrete and define if for us, if possible. [Wink]
 
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Would you like that in Deutch, mori? [Big Grin] Film-Stärke - Eigenschaft eines Schmiermittels, das fungiert, um Abrieb oder Zählen zu verhindern von den Metallteilen. Best I can do. [Cheers!]
 
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23,591
427, this definition only says film strenght is a "property" of a lubricant. Then the purpose of a lubricant is stated. Clearly, film strength is the mojo of oil. [Wink]
 
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Millbrae, CA
""Given the above, Film Strength looks to be a very general term that is kinda' meaningless unless many of the other parameters involved are specified and are put into context"" Film strength to me is a oils level of perfromance to reduce or eliminate oil film rupture due to grit, load or asperities in the rotating elements. "wear" Improveing the "film Strenght" can be done with anti scuff additives OR increasing the oil Viscosity. bruce
 
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7,409
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Austin, TX
quote:
Originally posted by bruce381: Film strength to me is a oils level of perfromance to reduce or eliminate oil film rupture due to grit, load or asperities in the rotating elements. "wear" Improveing the "film Strenght" can be done with anti scuff additives OR increasing the oil Viscosity. bruce
Interesting. Is that your personal definition, or is that out of something such as a Tribology handbook? Do you consider it to be a general property, or a more specific one with physical quantities that can be expressed in terms of combinations of basic dimensions?
 
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Sarasota, Florida
It seems that film thickness is dependent on viscosity. This in itself has little to do with wear. Film strength is the ability to keep parts from wearing when they are forced to the point of touching. It will take a higher force to make parts wear if they touch under the influence of a higher film strength lubricant. This goes along with the observation that thinner wt. oils with the latest, newest additives are able to be used in engines having 6 - 700 BHP. It relates to the ability of F1 engines to run at 20,000 RPM for hours and even multiple practice sessions and then two races without a rebuild. The ability to win that second race says there is a lot of that engine left after the first race. aehaas
 
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southwest
so,film thickness is directly proportinal to oil thickness(viscosity) and inversely proportional to base oil quality and/or the quality of the additive package(poor base oil/add pkg+higher wear;good base oil/add pkg lower wear) .these factors, if I understand you correctly have little or nothing to do with film strength or how thin or thick the flavor of oil chosen
 
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3,478
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Millbrae, CA
quote:
Originally posted by 427Z06:
quote:
Originally posted by bruce381: Film strength to me is a oils level of perfromance to reduce or eliminate oil film rupture due to grit, load or asperities in the rotating elements. "wear" Improveing the "film Strenght" can be done with anti scuff additives OR increasing the oil Viscosity. bruce
Interesting. Is that your personal definition, or is that out of something such as a Tribology handbook? Do you consider it to be a general property, or a more specific one with physical quantities that can be expressed in terms of combinations of basic dimensions?

Out of my head 32 years triboligy CLS. As I remember that is the general deffinition it is some what of a gereral property of lubricants. ALL will have a "film strenght" thicker oils will have a higher or thicker film and additives will also play a BIG part I'm sure there is a mesurement or maybe Coeffecient of friction would be used. Again I here and use this term to say if that "crank or bearing is wearing to fast them incresing the film strenght will help" Do this with a higher vis oil or more/different anti scuff additives. Different oils will have a different "value" mineral being OK esters being better etc. bruce
 
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7,409
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Austin, TX
quote:
Originally posted by bruce381: Out of my head 32 years triboligy CLS. As I remember that is the general deffinition it is some what of a gereral property of lubricants.
So in other words, there is no "official" specific definition with physical quantities that can be consistently expressed in terms of a combinations of basic dimensions?
 
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