Hello everyone,

I am making a drawing for CNC machined part. The part required a quite tight surface finish tolerance.
I have attached the surface roughness specification given for that surface in ISO standard in a drawing I have.

Please see surface.png

I have difficulty in interpreting the attached surface finish spec and putting it as per the ASME standard.


Here's what I think about the given surface finish in the attached image.

Rz is the average height of 5 highest peaks and valleys and the 4 is the value in micrometres.
None of the 5 heights should cross 5 micrometres.

Please correct me if I am interpreting it wrong. And how can I put that in ASME standard drawing? As far as I know, ASME prefers Ra instead of Rz, and I am not sure how the manufacturer in USA would interpret if put it as it is.

Please help me.

Thank you in advance.