Accuracy notation change (Regarding MPE notation) The “instrumental error” used until now will change to “MPE ( E MPE / S MPE )”. Scale Shift Error ( S MPE ) will describe the permissible error including those for depth and step.( Table 4 )
Accuracy 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 ( S MPE )” for “calipers whose measuring face is other than the zero-setting face = calipers with exclusive measuring method” such as centerline calipers, inside calipers, etc. ( Fig. 5, Table 7 ) Accuracy is described using S MPE 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.
E MPE
S MPE
Standards
Outside measurement Accuracy notation for outside measurement Accuracy notation for outside measurement
Inside measurement
Depth measurement
Step measurement
I.D. measurement
Permissible values including those for all measurements: inside, depth, step, etc.
ISO13385-1:2019
ISO13385-1:2011 ( JISB7507:2016 ) Depth, step, = E MPE + 0.02 mm Maximum permissible error includes the repeatability and quantizing error. Inside measurement = E MPE
573-605-20 ( Fig. 5 ) Non-ISO model ( Ex. )
Small hole measurement ( S MPE ) ▼
Depth measuring unit ( S MPE ) ▼
573-646-20
Test points and MPE notation
D
◀ Inside measurement ( S MPE )
Step measurement ( S MPE ) ▶
◀ Zero-setting face
◀ Zero-setting face
◀ ◀ Outside measurement ( E MPE ) ◀
( Table 7-2 ) Maximum permissible error (MPE) E MPE (mm) S MPE (mm) — ±0.03 Number of test points: 3 No outside measuring face ▲ Inside measuring unit ( S MPE )
No outside measuring face
▲ Pitch measuring unit ( S MPE ) ( Table 7-1 ) Maximum permissible error (MPE) E MPE (mm) S MPE (mm) — ±0.04 Number of test points: 3
Ex.) 200 mm caliper ( Table 4-1 ) Accuracy ±0.02 mm (conventional notation)
Outside measurement Inside measurement
±0.02
Breakdown
±0.02 For depth and step measurement, add 0.02 mm to the outside measurement value.
S MPE 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 S MPE 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 )
Ex.) Permissible values for a 200 mm caliper ( Table 6-2 ) Measured length (mm) Maximum permissible error (MPE) E MPE (mm) S MPE (mm) 0 ≤ L ≤ 50 ±0.02 ±0.04 50 ≤ L ≤ 100 ±0.02 ±0.04 100 ≤ L ≤ 150 ±0.02 ±0.04 150 ≤ L ≤ 200 ±0.02 ±0.04
( Table 6-1 )
Unit: mm
Scale interval, graduation or resolution 0.05 0.02 or 0.01 ±0.05 ±0.02
➡
Measured length
50 or less
Over 50, 100 or less ±0.06
±0.03
Over 100, 200 or less Over 200, 300 or less
±0.07
±0.08 ±0.04 Note: E MPE includes the measurement error arising from straightness, flatness and parallelism of the measuring surface. Maximum permissible error E MPE of Partial surface contact error in JIS B 7507
Ex.) Breakdown of S MPE Inside measurement Step measurement
Depth measurement
I.D. measurement
+ 0.01 −0.03
±0.02 ±0.04 ±0.04
D-46
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