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]

In Reply to Parent Post by reddy

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]

In Reply to Parent Post by reddy

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/qual...ace.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]

In Reply to Parent Post by harry

Also have a look at these threads.

Hello Harry,

Somehow, the link did not work.

Stijloor.