DD-71Depth Gage Performance Evaluation MethodJIS B 7518 was revised and issued in 2018 as the Japanese Industrial Standards of the depth gage, and the “Instrumental error” indicating the indication error of the depth gage 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 2018.Maximum permissible error of partial measuring face contact EMPE [JIS B 7518: 2018]The Maximum permissible error EMPE of a depth gage is an indication error applied to depth measurement.Table 1 shows the Maximum permissible error EMPE of the indication value of the partial measuring surface contact error.EMPE for any desired height is obtained by measuring the height of two equal length gauge blocks, or equivalent, with a height gage on a precision surface plate (Fig. 3) and then subtracting the gauge block size from the measured size.Fig. 1Fig. 2Conventional JIS Instrumental errorJIS B 7518-1993 Conformity rangeSpecication rangeAcceptance rangeNon-conformity rangeNon-conformity rangeNew JIS Maximum permissible error (MPE)JIS B 7518: 2018 (ISO/TR 14253-6: 2012)When a condition considering uncertainty is satisedSpecication range＝Conformity rangeNon-conformity rangeConformity rangeNon-conformity rangeSpecication rangeUncertaintyrangeUncertaintyrangeU(Rejected)(Rejected)AcceptanceUUUUncertainty is not included in judgmentSpecication range＝Acceptance rangeTable 1: Maximum permissible error EMPE of partial measuring face contact of a conventional depth gageUnit: mmMeasurement depthScale interval, graduation or resolution0.050.02 or 0.0150 or less±0.05±0.02Over 50, 100 or less±0.06±0.03Over 100, 200 or less±0.07Over 200, 300 or less±0.08±0.04Over 300, 400 or less±0.09Over 400, 500 or less±0.10±0.05Over 500, 600 or less±0.11Note: EMPE includes the measurement error arising from straightness, flatness of the measuring surface and parallelism with the reference surface.The “Instrumental error” indicating the indication error of JIS has been changed to “Maximum permissible error (MPE) of indication” for the following models:• SERIES 571 ABSOLUTE Digimatic Depth Gage described on page D-64 (All models)• SERIES 527 Vernier Depth Gage described on page D-65 (All models)• SERIES 527, 571 Hook End Type described on page D-66 (All models)• SERIES 571 Mini Depth Gage described on page D-67 (All models)Fig. 3: Determination of partial measuring face contact errorGauge blockGauge blockPrecision surface platePrecision surface plateHeight gageDepth gageDepth GagesQuick Guide to Precision Measuring Instruments
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