Surface Roughness

Surface Texture

Surface Texture Symbols, ASME/ANSI Y14.36M-1996, defines the American National Standard symbology for expressing desired surface finishes resulting from processing solid materials. Qualitative values can be expressed for roughness, waviness and lay. The Y14.36M standard does not address the manufacturing processes required to produce a particular surface texture value, nor how it is verified. Surface texture definitions and texture verification methods are shown in ASME/ANSI B46.1-1995, Surface Texture (Surface Roughness, Waviness and Lay).

The use of surface texture symbology is optional. Where no surface texture symbology is used, the surface finish may be considered satisfactory if it is produced within the limits of size and form in accordance with ASME/ANSI Y14.5M-1994. When surface texture symbology is used, it is considered applicable to the finished surface of the object.

ISO Surface Finish Designations

ISO standards are published in a different fashion than American National standards in that they are written as smaller focused documents (often called parts), which in turn reference other standards or other parts of the same standard. In the case of surface finish, numerous individual standards taken as a whole form a set of standards roughly comparable in scope to American National Standard ANSI/ASME Y14.36M (See Section 11.2 for complete coverage on ANSI/ASME Y14.36M). To add to the confusion of U.S. users, and unlike the numbering scheme used by ANSI, ISO standards on a particular topic often do not carry sequential numbers, nor are they in consecutive series.

The primary ISO standard dealing with surface finish, ISO 1302:1992 is concerned with the methods of specifying surface texture symbology and additional indications on engineering drawings. This and all ISO standards are expressed in SI metric units, with commas (,) used as decimal points. Other ISO standards are referenced for constituent provisions, but not directly discussed in the ISO 1302 standard. For instance:

    ISO 468:1982 Surface roughness Parameters: Their values and general rules for specifying requirements.
    ISO 4287:1997 Surface texture: Profile method Terms, definitions and surface texture parameters.
    ISO 4288:1996 Surface texture: Profile method Rules and procedures for the assessment of surface texture.
    ISO 8785:1998 Surface imperfections Terms, definitions and parameters.
    ISO 10135-1:CD Representation of parts produced by shaping processes Part 1: Molded parts.