〔 TECHNICAL DATA 〕 SURFACE ROUGHNESS REFERENCE: JIS B 0601(1994) JIS B 0031(1994)
〔 TECHNICAL DATA 〕 TECHNICAL DRAWINGS–METHOD OF INDICATING SURFACE TEXTURE ON DRAWING REFERENCE: JIS B 0031(1994)
1. Categories of surface roughness Definitions and indications for surface roughness parameters for industrial products are specified. They are arithmetical mean roughness (Ra), maximum height (Ry), ten–point mean roughness (Rz), mean spacing of profile irregularities (Sm), mean spacing of local peaks (S) and load length ratio (tp). Surface roughness is given as the arithmetical mean value for each part randomly extracted from the surface of the target object. 〔 Mean center line roughness (Ra 75 ) is defined in the annexes of JIS B 0031/JIS B 0601. 〕
Positions of each indicating symbol relative to indicating symbol of surface The indicating symbols for surface texture are expressed by arranging in positions as shown in Drawing 1. This includes surface rough- ness value, cutoff value or reference length, processing method, symbol of direction of lay, surface waviness, etc.
Drawing 1 Entry position of each indicating symbol
a: Value of Ra b: Processing method c: Cutoff value/valuation length c ′ : Reference length/valuation length d: Symbol of direction of lay f: Parameter other than Ra (When tp, parameter/cutoff level) g: Surface waviness (according to JIS B 0610) Note Items other than a and f are added as necessary.
Typical ways for obtaining surface roughness
b f c ′
Arithmetical mean roughness Ra A section of only standard length is sampled from the direction of mean line on the roughness chart. The mean line of the sampled section runs in the direction of X–axis and longitudinal magnification in the direction of Y–axis. The value obtained with the formula on the right is expressed in micrometer (μm) when roughness curve is y = f (x). Maximum peak Ry ※ Rz in JIS B 0601 (2013) A section of only standard length is sampled from the direction of mean line on the roughness curve. The distance between the peaks and valleys of the sampled section is measured in the y direction of the roughness curve. The value is expressed in micrometer (μm). Note: To obtain Ry, sample only the standard length. The part, where there are no unusual peaks and valleys to be interpreted as scratches, should be avoided. Ten–point mean roughness Rz ※ Rz in JIS B 0601 (2013) A section of only standard length is sampled from the direction of mean line on the roughness curve. Measurement is done in the y direction from the mean line of the sampled section. The sum of average peak, obtained from the absolute values of elevation of 5 tallest peaks (Yp), and the average valley, obtained from the absolute values of elevation of 5 lowest valleys (Yv), is expressed in micrometer (μm).
a c
L
1
Y
Ra =
f (x) dx
e
d
g
e d
g
L
0
m
X
0
Reference: The location of e in Drawing 1 is given as the finishing allowance in ISO 1302.
l
■ Examples indicating surface texture on drawing Surface indicating symbol
Symbol
Meaning
Figure
l
The direction of the lay of the cutting blade due to machining is parallel to the projected plane of the figure with the symbol (ex.) Shaped surface
m
Indicating symbol of surface requiring removal process
Direction of lay of cutting blade
Ry=Rp+Rv
The direction of the lay of the cutting blade due to machining is perpendicular to the projected plane of the figure with the symbol (ex.) Shaped surface (when viewed from the side) machined or cylindrical ground surface The direction of the lay of the cutting blade due to machining intersects in two diagonal lines on the projected plane of the figure with the symbol (ex.) Honing finished surface
Indicating symbol of surface on which no removal process is permitted
m
Direction of lay of cutting blade
l
Examples indicating the upper limits of Ra (a) (b) (c)
Yp 1 + Yp 2 + Yp 3 + Yp 4 + Yp 5
Yv 1 + Yv 2 + Yv 3 + Yv 4 + Yv 5
+ 5
Rz =
Yp 1, Yp 2, Yp 3, Yp 4, Yp 5 : Elevation of tallest 5 peaks within sample with respect to standard length L Yv 1, Yv 2, Yv 3, Yv 4, Yv 5 : Elevation of lowest 5 valleys within sample with respect to standard length L
6.3
25
25
Direction of lay of cutting blade
25
6.3
25
The lay of the cutting blade due to machining cross in multiple directions or are non–directional (ex.) Lapped surface, super finished surface, face milled
Reference: Relationship between arithmetical mean roughness (Ra) and conventional symbols
Examples indicating direction of lay
Ten–point mean roughness Rz
Arithmetical mean roughness Ra
Max. Height Ry
Standard length of Ry/Rz L (mm)
Conventional finish symbol
Standard number series Cut–off value c(mm) Indication of surface texture on drawings
Standard number series
or end milled surface in surfacing feed direction
0.08
0.012 a 0.025 a 0.05 a 0.1 a 0.2 a
0.05 s 0.1 s 0.2 s 0.4 s 0.8 s 1.6 s 3.2 s 6.3 s
0.05 z 0.1 z 0.2 z 0.4 z 0.8 z 1.6 z 3.2 z 6.3 z
0.08
0.25
0.012
– 0.2
The lay of the cutting blade due to machining is almost concentric to the center of the plane with the symbol (ex.) Facing surface
Examples indicating the upper and lower limits of Ra (a) (b)
0.25
0.8
6.3 1.6
0.4 0.8 1.6 3.2 6.3
a a a a a a a a a
0.8
0.4
– 1.6
1.6 6.3
12.5 s 25 s
12.5 z 25 z
3.2
– 6.3
2.5
The lay of the cutting blade due to machining is almost radial to the center of the plane with the symbol
2.5
Examples indicating processing method
12.5
50
s s s s
50
z z z z
12.5
– 25
(a)
(b)
25 50
100 200 400
100 200 400
8
Milling
M
8
50
– 100
3.2
3.2
–
100
–
–
＊ The interdependence for 3 classes represent a relationship for convenience and are not strictly enforced. ＊ The evaluation lengths of Ra: Ry and Rz are five times the cut–off value and standard length respectively. Note) JIS B 0601 has been significantly revised since 2001. See the JIS handbook for latest information.
Note) JIS B 0031 has been significantly revised since 2003. See the JIS handbook for latest information.
1221
1222
Powered by FlippingBook