surface texture

This is what ASME Y14.5 has to say concerning surface texture.

[B]1994: 3.3.21 Surface Texture Symbols[/B]. For information on the symbolic means of specifying surface texture, see ANSI Y14.36.

[B]2009: 1.8.21 Surface Texture.[/B] Methods of specifying surface texture requirements are covered in ASME Y14.36M. For additional information, see ASME B46.1.

I do not currently have copies of ASME Y14.36M or ASME B46.1.

Two people at my work have asked if form tolerances (and rule #1, when in effect) eliminate the need for surface texture requirements. Asked another way, does form also control surface finish?

The standard appears to allow the use of surface finish call outs. Can surface finish be used with form controls? Will one refine the other depending upon the geometric tolerance specified vs. surface finish value specified? What are the instances where it does and does not make sense to use them together?

Thank you!

[QUOTE=Andrew T;12561]Two people at my work have asked if form tolerances (and rule #1, when in effect) eliminate the need for surface texture requirements. Asked another way, does form also control surface finish?[/QUOTE] Absolutely NOT!

Rule #1 establishes a 3D boundary at MMC and is not meant as a substitute for controlling the local surface peaks and valley's as the surface roughness specification does. Additionally, form tolerances such as Flatness or cylindricity are not substitutes for surface roughness specification.

Seriously, you can a limits of size .0001 and have a surface roughness of Ra 250.

*** However, it is possible to specify a limits of size tolerance smaller than your surface roughness functional requirements. But, this is not the intent. ***