How to explain the increase or the decrease of the surface roughness after the friction

[afry]

Hello,

I'm doing friction test with WC tools with different surface texture and CBN tool against workpiece made of steel. After the frition test carried out with a normal load of 50N,I noticed that the roughness of the workpiece worked with CBN decreases whereas the roughness of the workpiece worked with WC tools decreases. I attached an histogramm with the roughness of the workpiece before and after the friction test.
I would like to know why the surface roughness of the workpiece increases with WC tools and decreases with CBN tool?
Is it due to the wear behavior of the tools?

Thank you in advance for your help

 

[racookpe1978]

Post a picture of the actual surfaces - before and after the tests, for as many of the surfaces as possible. Galling between the two is possible, but not an exclusive answer.

 

[afry]

Hello,

Thank you for your answer. I attached a pic of the surface of a workpiece.
All the workpieces have always the same marks on it whenhever the tool used.

 

[tomwalz]

My first thought would be to inquire as to what grain size you have in the carbide. There is a huge range of grain sizes. You might think of it as the range of grain sizes in sandpaper.

I would wonder how this tungsten carbide has been prepared. Often tungsten carbide is sandblasted after sintering to clean it up.

There are lots of other possible considerations but I believe I would start by making sure that you are using the same grain size in both applications.

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[racookpe1978]

Hmmn. Based on the orientation of the picture, what direction was the movement of the two samples in the picture?

 

[UconnMaterials]

afry,

Have you considered that you may be getting work-piece pickup in the WC tool-piece that is causing the roughness to increase? Do you have an SEM or optical profilometer available? These tools will be valuable in helping you get your answer.

Uconmaterials