Hello Dr. Wederley Miranda,

In the case of piston ring-cylinder tribo pair, the insufficient lubrication leads to this kind of wear called scuffing. The process of events leading to scuffing presented next :

1. The shortage of oil between piston ring and cylinder liner cause a plastic deformation in sufrace liners.

2. The two surfaces of piston ring and cylinder are very close (small amount of oil), thus the asperities removed.Hence, the contact area between piston ring and cylinder liner increased accordingly.

3.Finally, in the critical situation the two surfaces have a metallic contact causing adhesion,so the wear appeared.

Regards,

Anastasios

Thank you for your answer, Anastasios.

So, do you mean the starting point for the scuffing on piston rings is the shortage of oil? Which other problems could lead to scuffing?

Could you recommend any papers on this subject?

Regards,

Wederley

Scuffing may be occurred due to inclusions in the lubricating oil, or soots generated after combustion that reduces the effect of lubrication and friction occurs at the junction of mating surfaces.

Yes i think that the first step is the lack of lubricant oil between ring liner and cylinder. Detailed, when the piston ring is near to reversal points (TDC and BDC accordingly) the contact of two surfaces can be appeared ( for example: low velocity and high pressure at TDC).

 About this topic i have some papers to recommend to you:

(1) Jensen, M.F., Bøttiger, J., Reitz, H.H., Benzon, M.E., Simulation of Wear Characteristics of Engine Cylinders, Wear 253 p. 1044-156, 2002

and

(2) P Papadopoulos, M Priest and W. M. Rainforth ,Investigation of fundamental wear mechanisms at the piston ring and cylinder wall interface in internal combustion engines Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology March 1, 2007 221: 333-343, DOI:10.1243/13506501JET254

Regards,

Anastasios

Thank you again. Very interesting publications!

Dear Wederley,

I recommend the following paper of Prof. Ludema:

K.C. Ludema, A review of scuffing and running-in of lubricated surfaces, with asperities and oxides in perspective, Wear, 100 (1984), pp. 315–331

I hope this will help you.

Best regards to you and to Anastasios.

Michel

Dear Wederely,

I, also, agree with above comments.  Scuffing wear is completely different from other types of wear.  The reason for this, it occurs, when starvation of lubrication between contact surfaces lead to breakdown of lubricant film thickness.  As consequence of this, direct asperity contacts made (metal to metal) between surfaces and further a strong adhesive exit between them.  If conducive environment present ( high speed and high load) between surfaces, it leads cold welding process (high flash temperature) at asperity junction.  If this continues with in a short duration, scuffing wear occur.  Thus, scuffing wear is purely based on adhesive type and it occurs ONLY when there is breakdown of lubricant film thickness. 

Hope this would helpful to you. 

Many Thanks,

Ramkumar

Many thanks, both of you. By the way, regarding Ludema and Michel Fillon, I would like to recommend these books in tribology:

LUDEMA, K. C. Friction, wear, lubrication: a textbook in tribology. Boca Raton: CRC Press, 1996. 257p

Encyclopedia of Tribology, 1st edited by Wang Q. Jane, Chung Yip-Wah, 04/2013:  Springer, New York.

Best regards,

Wederley

Dear Wederley,

Of course, in the case of piston ring-cylinder, the lack of lubricant is the reason of scuffing activation - but the mechanism has an adhesive character in my opinion. Generally, several theories have been suggested in the literature but none of them unequivocally determine the evolution of scuffing. The most relevant of them connect the initiation of scuffing with critical temperature (ex. Blok), debris generation (ex. Rabinowicz, Enthoven&Spikes), plastic deformation of asperities , destruction of protective oxide films, desorption of polar constituents of lubricant (Batchelor&Stachowiak), adiabatic shear instability (Hershberger), energetic activation of surfaces (Semenov), surface polarity, friction power (Matveevsky) etc. Unfortunately, the mechanism of activation depends on many factors (including type of lubricant or additives, features of materials, geometry of friction pair etc.) 

Best regards

Lukasz

Dear colleague, 

By its definition, scuffing is adhesive wear. The scuffing phenomena usually appears at high sliding speed and / or high contact pressure, when the temperature of the tribological contact reaches important values. Scuffing can be avoided by proper lubrication.

The general wear phenomenon is also influenced by the action of the abrasive particles. But the abrasive wear can be also avoided by proper filtering of the lubricants.

Between the different wear modes (rolling contact fatigue, abrasion, scuffing, corrosion etc.) there is a real competition, one wear type influencing the others.

Definitely, scuffing is adhesive wear.

Best regards,

Viorel

Thank you all for the additional comments.

Dear Łukasz, could you send the papers you've cited in your answer, or the complete references?

I am very interested if you have any paper about "What is the best way to classify scuffing? Adhesive or abrasive wear? ".

Prof. Kaleli

[email protected]

Dear Professor Kaleli,

I don't have any paper about scuffing, but I've read some publications that may be useful for you:

Article Tribological characteristics and surface interaction between...

Article Evaluation of ring surfaces with several coatings for fricti...

Article Comparison of scuffing life between unidirectional and recip...

Article Simulation of wear characteristics of engine cylinders

Article The anti-scuffing performance of diamond nano-particles as a...

Article Scuffing behavior of gray iron and 1080 steel in reciprocati...

Article The effect of various surface treatments on piston pin scuff...

Article Investigation of fundamental wear mechanisms at the piston r...

Definitely adhesive wear! (see "Tribology - Friction And Wear Of Engineering Materials" from Hutchings)

Adhesive wear(see "Guide to Friction, Wear,

and Erosion Testing" by Kenneth G. Budinski)