friction coefficient
friction coefficient
(OP)
Hi!
Could someone suggest me some formula to evaluate friction coefficient
- between two rough surface
- without lubrication
- with high pressure
Thank you
Manini
Could someone suggest me some formula to evaluate friction coefficient
- between two rough surface
- without lubrication
- with high pressure
Thank you
Manini





RE: friction coefficient
I also seem to recall in school that the horizontal friction equal to vertical load times the friction coefficient. The high pressure therefore doesn't change the frictional characteristic but can alter only the magnitude of the horizontal pull.
Have the the technology advanced so much that the formulas are available and there is no need to know what material is involved?
RE: friction coefficient
Yes, it’s true. For low force value (low pressure) friction coefficient is independent to pressure, but when the pressure is high, friction coefficient depend also to pressure. (I don’t know this correlation).
About material. I expect that correlation contain some material property and also some geometrical property of the surfaces (roughness). So I’d like to find some correlation like
Friction coefficient=function(load, material properties, geometrical properties)
Thank you again
By
Manini
RE: friction coefficient
W sin È = µN
where
W= weight
È= inclined angle
µ= static friction
N= Normal force (equal to the weight for equilibrium, therefore dividing both sides by "W cos È" gives us "tan È = µ" )
RE: friction coefficient
STF
RE: friction coefficient
It is one of those things I always get stumped on when doing calculations. e.g. does one use 0.05, 0.1 or 0.2, it has a huge effect on results.
RE: friction coefficient
0.05 is real slippery for sliding surfaces, 0.2-0.4 is normal, and 1 is decidedly sticky.
The problem is that there are so many gotchas that if your design is at all expensive or critical then you HAVE to do the test - the one I particularly liked in another thread was the difference that the normal oxide layer on steel makes. In my own experience we discovered interesting things about the effect of water, oil, and a combination of the two, on the friction of polyurethane.
Cheers
Greg Locock
RE: friction coefficient
...or find someone familiar with your application who has "done it all before" and can tell you what value to use. Preferably someone (or something) within your organization, like a design guidelines database.
RE: friction coefficient
The problem is more clear
By
Manini