B-70BMitutoyo reserves the right to change any or all aspects of any product specication, including prices, designs and service content, without notice.B-70BMicrometer Performance Evaluation MethodMaximum Permissible Error of Full Surface Contact Error JMPE [JIS B 7502: 2016] JIS B 7502 was revised and issued in 2016 as the Japanese Industrial Standards of the micrometer, and the “Instrumental error” indicating the indication error of the micrometer has been changed to “Maximum Permissible Error (MPE) of indication”.The “Instrumental error” of the conventional JIS adopts acceptance criteria that the specication range (precision specication) equals acceptance range, and the OK/NG judgment does not include measurement uncertainty (Fig. 1).The “Maximum Permissible Error (MPE) of indication” of the new JIS employs the basic concept of the OK/NG judgment taking into account the uncertainty adopted in the ISO standard (ISO 14253-1).The verication of conformity and nonconformity to the specications is clearly stipulated to use the internationally recognized acceptance criteria (simple acceptance) when the specication range equals the acceptance range, and it is accepted that the specication range equals the acceptance range if a given condition considering uncertainty is met.The above said internationally recognized acceptance criterion is ISO/TR 14253-6: 2012 (Fig. 2).The following describes the standard inspection method including the revised content of JIS 2016.The full surface contact error of the outside micrometer is an indication error measured by contacting the entire measuring surface with the object to be measured at an arbitrary point in the measuring range.The value can be obtained by adjusting the reference point using a constant pressure device with the minimum measuring length of the micrometer, inserting a grade 0 or 1 gauge block prescribed in JIS B 7506 or an equivalent or higher gage between the measuring surfaces (Fig. 3), and then subtracting the dimensions of the gauge block from the indication value of the micrometer using a constant pressure device.Fig. 1Fig. 2Conventional JIS Instrumental errorJIS B 7502-1994 Conformity rangeUncertainty is not included in judgmentSpecication range＝Acceptance rangeSpecication rangeAcceptance rangeNon-conformity rangeNon-conformity rangeNew JIS Maximum Permissible Error (MPE)JIS B 7502: 2016 (ISO/TR 14253- 6: 2012) When a condition considering uncertainty is satisedSpecication range＝Conformity rangeNon-conformity rangeConformity rangeNon-conformity rangeSpecication rangeUncertainty rangeUncertainty rangeU(Rejected)(Rejected)AcceptanceUUUFig. 3: Measurement of full surface contact errorGauge block
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