Machinery's Handbook, 31st Edition
ISO Surface Texture Symbology Examples
827
Examples of ISO Applications of Surface Texture Symbology Example 1: Surface roughness in Fig. 8 is produced by milling with a bilateral tolerance between an upper limit of Ra = 55 m m and a lower limit of Ra = 6.2 m m. Both apply the “16%-rule” default (ISO 4288). Both transmission bands are 0.008 - 4 mm, using default evaluation length (5 × 4 mm = 20 mm) (ISO 4288). The surface lay is circular about the center. U and L are omitted because it is obvious one is upper and one lower. Material removal is allowed. Milled 0.008-4 / Ra 55 C 0.008-4 / Ra 6.2 Fig. 8. Ground Ra 1.5 -2.5 / Ramax 6.7 Fig. 9. Example 2: Surface roughness in Fig. 9 is produced by grinding to two upper limit speci fications: Ra = 1.5 m m and limited to Rz = 6.7 m m max. The default “16%-rule,” default transmission band and default evaluation length apply to the Ra , while the “max-rule”, a - 2.5 mm transmission band and default evaluation length, apply to the Rz . The surface lay is perpendicular relative to the plane of projection, and material removal is allowed. Example 3 : Fig. 10 indicates a simplified representation where surface roughness of Rz = 6.1 m m is the default for all surfaces as indicated by the Rz = 6.1 specification, plus basic symbol within parentheses. The default “16%-rule” applies to both as does the default transmission band (ISO 4288 and ISO 3274). Any deviating specification is called out with local notes such as the Ra =0.7 m m specification. There is no lay requirement, and material removal is allowed.
Fe/Ni10b Cr r
Ra 0.7
Fe/Ni20p Cr r
-0.8 / Ra 3.1 U -2.5 / Rz 18 L -2.5 / Rz 6.5
Rz 1
( ) Rz 6.1 Fig. 10.
Fig. 11. Fig. 12. Example 4: Surface treatment without any material removal allowed is indicated in Fig. 11 , and to a single unilateral upper limit specification of Rz = 1 m m. The default “16%- rule,” default transmission band and default evaluation length apply. The surface treatment is nickel-chrome plated to all surfaces shown in profile (outline) in the view where the symbol is applied. There is no lay requirement. Example 5 : In Fig. 12, surface roughness is produced by any material removal process to one unilateral upper limit and one bilateral specification: the unilateral Ra = 3.1 is to the default “16%-rule,” a transmission band of -0.8 mm and the default evaluation length (5 × 0.8 = 4 mm). The bilateral Rz has an upper limit of Rz = 18 m m and a lower limit of Rz = 6.5 m m. Both limits are to a transmission band of - 2.5 mm with both to the default 5 × 2.5 = 12.5 mm. The symbols U and L may be indicated even if it is obvious. Surface treatment is nickel/chromium plating. There is no lay requirement. Example 6: Surface texture symbology may be combined with dimension leaders and witness (extension) lines, as in Fig. 13. Surface roughness for the side surfaces of the key way is produced by any material removal process to one unilateral upper limit specifica tion, Ra = 6.5 m m. It is to the default “16%-rule,” default transmission band and default evaluation length (5 × l c) (ISO 3274). There is no lay requirement.
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