Friction: aluminium on carbon

[nilsvoorkamp1]

I need the coefficient of kinetic friction for movement between greasy aluminium on carbon.
It's nowhere to be found on the internet.

Thanks in advance!

 

[Bystander]

Summary:: I need the coefficient of kinetic friction for movement between greasy aluminium on carbon.
It's nowhere to be found on the internet.

Thanks in advance!

on carbon.

Graphitic? Amorphous? Diamond?

Summary:: I need the coefficient of kinetic friction for movement between greasy aluminium on carbon.
It's nowhere to be found on the internet.

Thanks in advance!

greasy aluminium

Anodized? Hard? Soft?

 

[Dr_Nate]

Summary:: I need the coefficient of kinetic friction for movement between greasy aluminium on carbon.
It's nowhere to be found on the internet.

Thanks in advance!

I need the coefficient of kinetic friction for movement between greasy aluminium on carbon.
It's nowhere to be found on the internet.

Thanks in advance!

You could also try to measure it yourself.

 

[berkeman]

I need the coefficient of kinetic friction for movement between greasy aluminium on carbon.

0.15 +/- 0.03

You're welcome.

 

[nilsvoorkamp1]

0.15 +/- 0.03

You're welcome.

Thanks for your reply!
Do you have the source of where you find this number?

 

[nilsvoorkamp1]

Graphitic? Amorphous? Diamond?

Anodized? Hard? Soft?

hard

 

[Cutter Ketch]

Summary:: I need the coefficient of kinetic friction for movement between greasy aluminium on carbon.
It's nowhere to be found on the internet.

Thanks in advance!

I need the coefficient of kinetic friction for movement between greasy aluminium on carbon.
It's nowhere to be found on the internet.

Thanks in advance!

Greasy? As in lubrication? Your answer is going to be more about the grease than the aluminum and carbon. Although the texture of the aluminum and carbon will have effects on the grease, the coefficient of friction will depend on the viscosity of the grease which will in turn depend on the temperature and pressure (and of course the make up) of the grease. Heck, it will depend on how old the grease is and how long it has been working. This information will be measured. It can’t reasonably be calculated. The only place you will find published tables for the measured behavior of a lubricating grease will be from the manufacturer of the grease.

As an example, here is a paper turned up in a quick internet search that highlights the complexity of the behavior of the coefficient of friction of lubricating grease.

https://res.mdpi.com/d_attachment/l...-00042/article_deploy/lubricants-05-00042.pdf

 

[cjl]

0.15 +/- 0.03

You're welcome.

I suspect it's more like 0.15+/- 0.5, depending on the details of the grease and the surfaces. I don't think you can nail it down nearly that precisely without more information.

 

[nilsvoorkamp1]

I suspect it's more like 0.15+/- 0.5, depending on the details of the grease and the surfaces. I don't think you can nail it down nearly that precisely without more information.

Do you have a source for that?

 

[jrmichler]

There is no such thing as an exact coefficient of friction between two materials. The friction is a function of the materials, their surface properties, surface roughness, surface topology, speed, load, lubricant properties, amount of lubricant, entrance conditions (is the leading edge sharp or upturned like a ski?), and more. Some search terms are Stribeck curve, tribology, friction, and coefficient of friction.

There is an SAE paper, 950698, titled Variation of Friction in a Strip Test Apparatus with Controllable Drawbead Penetration, that goes into the reasons why the friction coefficient changed (for example) from 0.15 to 0.075 and back to 0.15 during a single test. It was not due to the Stribeck curve. And it was repeatable with different materials, lubricants, and test conditions.

If you need a reasonably accurate friction coefficient, you will need to do your own testing.

 

[cjl]

Do you have a source for that?

No, but I don't think I need a source for saying that the friction coefficient can vary widely depending on the details of the grease, surfaces, etc.

 

[nilsvoorkamp1]

No, but I don't think I need a source for saying that the friction coefficient can vary widely depending on the details of the grease, surfaces, etc.

I'm talking about the value 0.15. I understand the number is not exact but that's ok. So i just want to put it in my project but I can't do that without showing where I got it form besides an internet forum.

 

[cjl]

My point with that statement is that 0.15 isn't a number that you should use. It could be off by a factor of 2 or 3 (or more). You really need to test your setup to figure out what the number should be.

 

[berkeman]

So i just want to put it in my project but I can't do that without showing where I got it form besides an internet forum.

Is this for schoolwork?

 

[berkeman]

Thread closed temporarily for Moderation...

 

[berkeman]

This thread will remain closed. The continuation thread is here:

https://www.physicsforums.com/threa...t-of-aluminum-on-lubricated-cast-iron.982795/

It turns out that @Thijske and @nilsvoorkamp1 are working on a school thesis project together, which is why they have posted fairly similar threads.