Surface Roughness - What is difference between Ra, Rmax & Rt

[reddy]

Can anybody help me in differentiating surface roughness measurment values in Ra,Rmax and Rt. In what conditions we use Rmax.

 

[Ted Schmitt]

Can anybody help me in differentiating surface roughness measurment values in Ra,Rmax and Rt. In what conditions we use Rmax.

Welcome to the Cove !

Average roughness (Ra). The average height of the bumps on a surface, measured in micrometres or microinches.

Rt = is the difference between the highest peak and the lowest valley

Rmax = is the highest peak

 

[Stijloor]

Can anybody help me in differentiating surface roughness measurment values in Ra,Rmax and Rt. In what conditions we use Rmax.

Hello reddy,

Here is some info.

http://www.mfg.mtu.edu/cyberman/quality/metrology/surface.html#para2

Hope this helps.

Stijloor.

 

[AndyN]

Surface finish is often called out for two reasons:-

Functional performance, such as in a sealing ring application, bearing surfaces;

Appearance, where the finish has to look or feel smooth, etc. or requires further processing

It would be helpful to know how your organization is applying Ra to it's products.

 

[tenaiwa]

Hello,
It depends on your application
Pls consider also
function surface vs No function
friction->rolling or sliding
clearance fit or press fit
dimension presion of product
stress/load exist or not (corner,concave angle..)

hope it helps a little.

 

[harry]

Also have a look at here, here and here.

 

[Stijloor]

Also have a look at these threads.

Hello Harry,

Somehow, the link did not work.

Stijloor.