Surface Roughness Surface Texture

DRAFTING MANUAL
Update 56 Update 56A. Harding* by: Bruce 1.0 INTRODUCTION 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 requiredto 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). Representation is as shown in Figure 1. While units expressed within these symbols should be consistent with the basic units expressed on the drawing, this and all newer ASMEY14 standards are illustrated with SI (metric) units. The “M” in the ASME Y14.36M designation is indicative of this, with SI units being the standard and preferred unit. However US customary units may be substituted where applicable and consistent with the principles shown. To that extent, the standard may be considered unitless. The use of surface texture symbology is optional. Where no surfacetexture 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.

Surface Roughness Surface Texture

Section K11.2 Page 1 February 1997*

2.0 THE BASIC SYMBOL Use of the basic surfacetexture symbol is indicated where the surface may be produced by any method. If the surface is to be produced to net form (where material removal is prohibited), the circle symbol is added to the basic symbol. Examples of this principle include surfaces that may be produced by die casting, forging, hot finishing, cold finishing, sintering, injection molding, or other processes where no materialneed be removed for acceptable surface finishes. See Figure 2.
Basic symbol with material removal prohibited (net form)

Basic symbol with material removal required

Basic Surface Texture Symbol

2

Basic symbol with value of minimum material removal required

Figure 2. Basic surface texture symbol and variations for 1) material removal prohibited, 2) material removal allowed, and 3)material removal allowed to a minimum value

3X Text Height Expands with text length

Text Height (1X)

Figure 1. ASME/ANSI Y14.36M-1995 Surface Texture Symbol Size and Proportion
1.5X Text Height

NOTES 1.6 00 00
3X Text Height Minimum +1X for each added line of text over two 60°

* Purdue University West Lafayette, Indiana 47907

GENIUM PUBLISHING

*Supersedes issue of November 1988Section K11.2 Page 2 February 1997*

DRAFTING MANUAL
Surface Roughness Surface Texture
Update 56

Where material removal by machining is required, a bar is added to the basic symbol over the “V.” Further refinement to the “machining required” variation may be achieved by adding a minimum material removal value to the symbol. See Figure 1. Regardless, when the basic symbol and itsvariants are used without values, the interpretation should be explained in a drawing note. Note that the use of the circle and bar modifiers are consistent with international symbols for “on” and “off.” 3.0 MEASUREMENT Unless otherwise specified, measurement of surface texture is accomplished in the direction giving the maximum reading, usually across the lay. 4.0 PARAMETERS SHOWN IN SURFACE TEXTURESYMBOLS 4.1 Roughness Average (Ra) is the principle parameter for specifying roughness, as defined in ASME/ANSI B46.1-1995. It is placed above the “V” on the surface texture symbol. The preferred series roughness averages for both customary inch and metric are shown in Table 1. 4.2 Roughness Cutoff or Sampling Width is placed under the horizontal line. Standard sampling ratings are defined in...