D-41DAccuracy notation change (for custom products)The ISO-2019 standard stipulates the accuracy notation for compliant products. However, nothing is stipulated for custom products that are not compliant with said standard (such as calipers with dedicated measuring faces), so for these products the notation of accuracy is left to the discretion of each manufacturer.Mitutoyo, with many custom calipers, describes MPE for all of its calipers based on the following line of thinking. For example, MPE is “Scale Shift Error (SMPE)” for “calipers whose measuring face is other than the zero-setting face = calipers with exclusive measuring method” such as centerline calipers, inside calipers, etc. (Figure 5, Table 7) Accuracy is described using SMPE measured not using the number of test points stipulated in the ISO-2019 standard, but rather with the same number of test points and testing method as before.Accuracy notation change (Regarding MPE notation)The “instrumental error” used until now will change to “MPE (EMPE/SMPE)”. Scale Shift Error (SMPE) will describe the permissible error including those for depth and step.(Table 4)SMPE is described for measurements other than the outside measurement, but the maximum permissible error for inside measurement remains the same as before.The permissible values for measurements other than the outside measurement (inside, depth, step, and inside diameter measurement) must be described as SMPE in line with the ISO-2019 standard. Since the permissible values for depth and step measurement are larger than those for inside measurement, this could give an impression that accuracy has suffered. However, this is simply due to the change of notation in accordance with the ISO-2019 standard; neither has the accuracy of the inside measurement deteriorated nor has the product performance changed. (Table 6-1, 6-2)Test points and MPE notationDepth measuring unit(SMPE)▼◀Inside measurement (SMPE)Small hole measurement (SMPE)▼Step measurement(SMPE) ▶◀◀Outside measurement (EMPE)◀StandardsEMPESMPEOutside measurementInside measurement Depth measurementStep measurementI.D. measurementISO13385-1:2019Accuracy notation for outside measurementPermissible values including those for all measurements: inside, depth, step, etc.ISO13385-1:2011 (JISB7507:2016)Accuracy notation for outside measurementInside measurement = EMPEDepth, step, = EMPE + 0.02 mmMaximum permissible error includes the repeatability and quantizing error. (Table 6-1)Unit: mmMeasured lengthScale 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±0.04Note: EMPE includes the measurement error arising from straightness, flatness and parallelism of the measuring surface.➡Ex.) Permissible values for a 200 mm caliper (Table 6-2)Measured length (mm)Maximum permissible error (MPE)EMPE (mm)SMPE (mm) 0 ≤ L ≤ 50±0.02±0.04 50 ≤ L ≤ 100±0.02±0.04100 ≤ L ≤ 150±0.02±0.04150 ≤ L ≤ 200±0.02±0.04Ex.) Breakdown of SMPEInside measurementStep measurementDepth measurementI.D. measurement±0.02±0.04±0.04+0.01−0.03573-646-20573-605-20 (Figure 5) Non-ISO model (Ex.)◀Zero-setting faceNo outside measuring face▲ Pitch measuring unit (SMPE) (Table 7-1)Maximum permissible error (MPE)EMPE (mm)SMPE (mm)—±0.04Number of test points: 3 (Table 7-2)Maximum permissible error (MPE)EMPE (mm)SMPE (mm)—±0.03Number of test points: 3Ex.) 200 mm caliper (Table 4-1)Accuracy ±0.02 mm (conventional notation)BreakdownOutside measurement±0.02Inside measurement±0.02For depth and step measurement, add 0.02 mm to the outside measurement value.Maximum permissible error EMPE of Partial surface contact error in JIS B 7507◀Zero-setting faceNo outside measuring face▲ Inside measuring unit (SMPE)
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