This International Standard specifies a method for determining departures from roundness by measuring variations in radius by means of contact (stylus) instruments.
It establishes
a) types of instruments and general requirements;
b) recommendations for the use of instruments;
c) procedures for calibration of instruments and verifica-tion of their characteristics.
This International Standard applies to the assessment of the departures from ideal roundness of a workpiece through the medium of a profile transformation, obtained under reference conditions, expressed with respect to any one of the following centres :
a) centre of the least squares circle;
b) centre of the minimum zone circle;
c) centre of the minimum circumscribed circle;
d) centre of the maximum inscribed circle.
Each of these centres may have its own particular application. The position of the least squares centre can be calculated from a simple explicit equation given in annex F.
Departures from roundness of the measured profile, procedure, calibration and determination of systematic errors of rotation are dealt with in annexes A to D, respectively. Annex E gives rules for plotting and reading polar graphs.
NOTES
1 Profile transformation is defined in ISO 6318.
2 Reference conditions include the stylus, frequency (imitations of an electric wave filter fif used), permissible eccentricity of the graphical or digital representation of the profile (generally 7 % to 15 % of its mean radius, see annex E), the position of the measured section or sections relative to some feature of the workpiece.
SIS SS-ISO 4291:1991 history
1991SIS SS-ISO 4291:1991 Methods for the assessment of departure from roundness — Measurement of varia- tions in radius