(ISo 4291 nternational Standard INTERNATIONALORGANIZATION FOR STANDARDIZATION·MEKAYHAPOAHAR OPTAHM3AUMHIOCTAHAAPTM3AUWM+ORGANISATION INTERNATIONALE DENORMALISATION Methods for the assessment of departure from roundness - Measurement of variations in radius Methodesd'évaluationdesécartsdecircularite-Mesuragedesvariations derayon First edition - 1985-09-15 UDC 531.717 Ref. No. ISO 4291-1985 (E) iO 4291-1985 (E) Descriptors : surface conditions, roundness measurement, measuring instruments, profile meters, error analysis. Price based on 18 pages Copyright International Organization for Standardization without license from IHS Not for Resale Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (iso member bodies). The work of preparing International Standards is normally carried out through iso technical committees. Each member the right to be represented on that committee, International organizations, govern- mental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the Iso Council. They are approved in accordance with isO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 4291 was prepared by Technical Committee ISO/TC 57, Metrology and properties of surfaces. International Organization for Standardization, 1985 Printed in Switzerland CoyheationarganizationfStandardizato d without license from IHS Not for Resale INTERNATIONAL STANDARD ISO4291-1985 (E) Methods for the assessment of departure from roundness --- Measurement of variations in radius Scope and field of application digital representation of the profile (generally 7 % to 15 % of its mean radius, see annex E), the position of the measured section or sections This International Standard specifies a method for determining relative to some feature of the workpiece. departures fromroundness by measuring variations in radius by means of contact (stylus) instruments. Reference 2 It establishes Iso 6318, Measurement of roundness -- Terms, definitions a) types of instruments and general requirements; and parameters of roundness. b) recommendations for the use of instruments; 3 Definitions c) procedures for calibration of instruments and verifica- tion of their characteristics. For the purposes of this International Standard, the definitions given in IS0 6318 apply. 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 4 Instruments conditions, expressed with respect to any one of the following centres : 4.1 Instrument types and general requirements a) centre of the least squares circle; Instruments of the styius type employed for the determination b) centre of the minimum zone circle; of departures from ideal roundness may be of one of two types : c) centre of the minimum circumscribed circle; a) a stylus and transducer rotating round a stationary d) centre of the maximum inscribed circle workpiece; Each of these centres may have its own particular application. The position of the least squares centre can be calculated from transducer. a simple explicit equation given in annex F. According to the nature of the output information, instruments for the measurement of roundness fall into two groups : Departures from roundness of the measured profile, procedure, calibration and determination of systematic errors of rotation a) proflle recording; are dealt with in annexes A to D, respectively. Annex E gives rules for plotting and reading polar graphs. b) with direct display of the values of the parameters. NOTES Both groups may be combined in one instrument. 1 Profile transformation is defined in iso 6318. Stylus instruments should comply with the require