ISO 3290-2 INTERNATIONAL STANDARD

ISO 3290-2:2014 STANDARD (CERAMIC BALLS: SILICON NITRIDE)
Precision grade
Variation of ball diameter (VDws)(µm) (a)
Deviation from spherical form (tDw)(µm) (a)
Surface roughness (Ra)(µm) (a)
Variation of ball lot diameter (VDwL)(µm)
Gauge interval (IG)
Description of preferred gauge
Subgauge interval
Description of subgauges (SG)
3
0.08
0.08
0.010
0.13
0.5
-5/-0.5.0,+0.5/+5
0.1
-0.2,-0.1.0.0,1.0.2
5
0.13
0.13
0.014
0.25
1
-5/-1.0,+1/+5
0.2
-0.4,-0.2.0.0,2.0.4
10
0.25
0.25
0.020
0.5
1
-9/-1.0,+1/+9
0.2
-0.4,-0.2.0.0,2.0.4
16
0.4
0.4
0.025
0.8
2
-10/-2.0,+2/+10
0.4
-0.8,-0.4.0.0,4.0.8
20
0.5
0.5
0.032
1
2
-10/-2.0,+2/+10
0.4
-0.8,-0.4.0.0,4.0.8
24
0.6
0.6
0.040
1.2
2
-12/-2.0,+2/+12
0.4
-0.8,-0.4.0.0,4.0.8
28
0.7
0.7
0.050
1.4
2
-12/-2.0,+2/+12
0.4
-0.8,-0.4.0.0,4.0.8
40
1
1
0.060
2
4
-16/-4.0,+4/+16
0.8
-1.6,-0.8.0.0,8.1.6
60
1.5
1.5
0.080
3
6
-18/-6.0,+6/+18
1.2
-2.4,-1.2.0.1,2.2.4
100
2.5
2.5
0.100
5
10
-40/-10.0.10/40
2.0
-4,-2.0.2.4
Notes
(a) The values do not take into account surface defects; hence, measurement shall be taken outside such defects.
TERMS, SYMBOLS AND DEFINITIONS
TERM
SYMBOL
DEFINITION
Surface faultiness
-
Element, irregularity or set of elements and irregularities of the actual surface, unintentionally or accidentaly during production, storage or surface usage. These types of elements or irregularities considerably differ from elements related to surface roughness and they should not been considered in the measurement of the surface roughness
Nominal ball diameter
Dw
Diameter value which is used for the general identification of a ball size
Single ball diameter
Dws
Distance between two parallel planes tangential to the actual surface of a ball.
Mean ball diameter
Dwm
Arithmetical mean of the largest and the smallest of the single diameters of a ball.
Variation of ball diameter
VDws
Difference between the largest and the smallest of the single diameters of a ball.
Deviation from spherical form
tDw
Greatest radial distance, in any equatorial plane, between the smallest circumscribed sphere and the greatest inscribed sphere, with their centres common to the least square sphere centre.
Ball lot
-
Defines quantity of balls manufactured under conditions presumed uniform and which is considered as an entity
Mean diameter of ball lot
DwmL
Arithmetical mean of the mean diameters of the largest ball and the smallest ball in a ball lot.
Variation of ball lot diameter
VDwL
Difference between the mean diameters of the largest ball and the smallest ball in a ball lot.
Ball grade
G
Specific combination of dimensional, form, surface roughness and sorting tolerances for balls. Ball grade is identified by the letter G and a number.
Ball gauge
S
Amount by which the mean diameter of a ball lot should differ from the nominal ball diameter, this amount being one of an established series. Each ball gauge is a whole multiple of the ball gauge interval established for the ball grade in question. A ball gauge, in combination with the ball grade and nominal diameter, should be considered as the most exact ball size specification to be used by a customer for ordering purposes.
Deviation of a ball lot from ball gauge
ΔS
Difference between the mean diameter of a ball lot and the sum of the nominal ball diameter and the ball gauge: ΔS=DwmL-(Dw+S).
Ball subgauge:
-
Amount of an established series of amounts, which is the nearest to the actual deviation from the ball gauge of a ball lot. Each ball subgauge is a whole multiple of the ball subgauge interval established for the ball grade in question. The ball subgauge, in combination with the nominal ball diameter and the ball gauge, is used by ball manufacturers to denote the mean diameter of a ball lot and should not be used by customers of ordering purposes.
Hardness
-
Measure of resistance to penetration as determined by specific methods
Surface roughness
Ra
Surface irregularities with relatively small spacings, which usually include irregularities resulting from the method of manufacture being used and/or other influences. These irregularities are considered within the limits that are conventionally defined, e.g., whitin the limits of the sampling length.
Waviness
-
Surface irregularities of random of periodical deviation from the ideal spherical form. It is recommended that waviness be evaluated as velocity amplutude. In practice, the waviness components are separated from the real surface by a waviness analyser (filters).
Revision n.1