Comparison
Comparison close

MEASURAND : Relative positions of the gauge surfaces with respect to the centre of the front surface of the first gauge
TRAVELLING STANDARD : A 1020 mm long step gauge with 51 steps

Degrees of equivalence: constant component, Dic and expanded uncertainty Uic
(k = 2), and proportional component, Dip and expanded uncertainty Uip (k = 2)

MEASURAND : Length between the ball centres of each ball bar
Ball bar material : 2 steel ball bars and one Super Invar ball bar

NOMINAL VALUES : 400 mm and 800 mm for steel ball bars and 800 mm for Super Invar ball bar

Degrees of equivalence, Di and expanded uncertainty Ui (coverage factor 2), for each ball bar with nominal value Lk 

L1 = 400 mm, steel ball bar

 

L2 = 800 mm, steel ball bar

Note that NMIJ and NMIA reported no results for steel ball bar with nominal length 800 mm.

 

L3 = 800 mm, Super Invar ball bar

Note that NMIJ and NMIA reported no results for Super Invar ball bar with nominal length 800 mm.

Comparison
Comparison close

MEASURAND : Relative positions of the gauge surfaces with respect to the centre of the front surface of the first gauge
TRAVELLING STANDARD : A 1020 mm long step gauge with 51 steps

Degrees of equivalence: constant component, Dic and expanded uncertainty Uic
(k = 2), and proportional component, Dip and expanded uncertainty Uip (k = 2)

Results are presented under A4 printable format in Summary Results (.PDF file).

MEASURAND : Length between the ball centres of each ball bar
Ball bar material : 2 steel ball bars and one Super Invar ball bar

NOMINAL VALUES : 400 mm and 800 mm for steel ball bars and 800 mm for Super Invar ball bar

Degrees of equivalence, Di and expanded uncertainty Ui (coverage factor 2), for each ball bar k

Results are presented under A4 printable format in Summary Results (.PDF file).

Comparison
Comparison close
CC comparison
Linked comparison
APMP.L-K5.2021
Metrology area, Sub-field Length, Dimensional Metrology
Description Calibration of a step gauge
Time of measurements 2021 - 2022
Status Measurements in progress
References

Protocol

Measurand Distances of the centres of the front and back faces of the individual gauges of the step-gauge with respect to the centre of the front face of the first gauge.
Transfer device Step gauge
Comparison type Key Comparison
Consultative Committee CCL (Consultative Committee for Length )
Conducted by APMP (Asia Pacific Metrology Programme)
Pilot institute NIM
National Institute of Metrology
China
Contact person Hengzheng Wei

+86 10 64524931
First Name Last Name
wwww@ww.www +356719836 Institute 1 Institute 1 Khmelnitskiy
Pilot laboratory
NIM

National Institute of Metrology, China, APMP

KRISS

Korea Research Institute of Standards and Science, Korea, Republic of, APMP

MSL

Measurement Standards Laboratory, New Zealand, APMP

NIMT

National Institute of Metrology (Thailand), Thailand, APMP

NMC, A*STAR

National Metrology Centre, Agency for Science, Technology and Research, Singapore, APMP

NMIA

National Measurement Institute, Australia, Australia, APMP

NMIJ AIST

National Metrology Institute of Japan, Japan, APMP

UME

TÜBITAK Ulusal Metroloji Enstitüsü, Türkiye, EURAMET

Comparison
Comparison close

MEASURAND : Relative positions of the gauge surfaces with respect to the centre of the front surface of the first gauge
TRAVELLING STANDARD : A 1020 mm long step gauge with 51 steps

The key comparison reference value, xR, is obtained by taking first the mean of the measurement results reported by PTB, METAS, NMIJ and NIST, and then by fitting a linear regression to obtain the constant xRc and proportional xRp parts such that
xR = xRc + xRp L, where L is the interval length in mm.
The combined standard uncertainty of xR is given by uR = uRc + uRp L, as explained in Appendix B on page 32 of the Final Report.

Degrees of equivalence relative to the key comparison reference value have been analysed into constant Dic and proportional Dip terms with expanded uncertainties (coverage factor k = 2) Uic and Uip, for each laboratory i, as explained in Appendix B on pages 32 and 33 of the Final Report.
The pair-wise degrees of equivalence are not computed for this comparison.

MEASURAND : Length between the ball centres of each ball bar
Ball bar material : 2 steel ball bars and one Super Invar ball bar.

NOMINAL VALUES : 400 mm and 800 mm for steel ball bars and 800 mm for Super Invar ball bar

For each ball bar k, the key comparison reference value, xRk, is obtained as the mean of all participants' values xik. The standard uncertainty, uRk, of key comparison reference value xRk, is obtained from the reported standard uncertainties uik, as given in equation 6 on page 25 of the Final Report.

The degree of equivalence of each laboratory i with respect to the key comparison reference value for each ball bar k is given by a pair of terms expressed in µm:
Dik = xik - xRk and its expanded uncertainty Uik (coverage factor 2) calculated from the equation 4 on page 16 of the Final Report.

The pair-wise degrees of equivalence are not computed for this comparison.

Comparison
Comparison close

MEASURAND : Relative positions of the gauge surfaces with respect to the centre of the front surface of the first gauge
TRAVELLING STANDARD : A 1020 mm long step gauge with 51 steps

The participants' reported values and corresponding standard uncertainties are given in Tables 2 and 4 of the Final Report (page 13 and page 15, respectively), for the 51 steps.
For each laboratory i, a linear regression was fitted on the data, so the measurement of 51 gauge surfaces is analysed into constant xic and proportional xip parts.
The measurement of laboratory i is thus expressed as xi = xic + xip L, where L is the interval length in mm. In the same way, the standard uncertainty of laboratory i is expressed as ui = uic + uip L.

VNIIM and INRIM withdrew during the comparison.
NRC and CSIR-NML did not report any data due to technical problems.
CENAM realised a re-measure in 2002.

MEASURAND : Length between the ball centres of each ball bar
Ball bar material : 2 steel ball bars and one Super Invar ball bar

NOMINAL VALUES : 400 mm and 800 mm for steel ball bars and 800 mm for Super Invar ball bar

xik : result of measurement carried out by laboratory i for ball bar k with nominal length Lk, expressed as the deviation from nominal length in µm
uik : combined standard uncertainty of xik reported by laboratory i

VNIIM and INRIM withdrew during the comparison.
NRC and CSIR-NML did not report any data due to technical problems.
CEM, CENAM, and METAS did not participate in the ball bars comparison.

NMIJ and NMIA reported results only for steel ball bar with nominal length 400 mm.