APMP Regional Comparison (APMP.L-K5) Calibration of Step Gauge€¦ · Beisanhuandonglu 18, 100013...

Asia-Pacific Metrology Programme

KRISS, Jan. 2011

APMP Regional Comparison (APMP.L-K5)

Calibration of Step Gauge

Final Report

KC APMP.L-K5.2005: Calibration of a Step Gauge Final Report

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Contents

1 Introduction

2 Organization 2.1 Participants 2.2 Form of comparison 2.3 Time schedule 2.4 Handling and transport of artefact

3 Description of the standard 3.1 Artefact 2.2 Damage

4 Measurement instructions 4.1 Traceability 4.2 Measurands 4.3 Measurement instructions 4.4 Inspection of the artefact 4.5 Alignment 4.6 Thermal expansion correction 4.7 Reporting of incomplete data

5 Stability of the step gauge

6 Measurement results

7 Measurement uncertainty

8 Analysis of the reported results 5.1 Simple mean data reference 5.2 Weighted mean data reference 5.3 Weighted mean data reference excluding outliers 5.4 Determination of reference values

9 Conclusion

Appendix A : Determination of the reference values


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1 Introduction

The metrological equivalence of national measurement standards will be determined by a set of key comparisons chosen and organised by the Consultative Committees of the CIPM working closely with the Regional Metrology Organizations (RMOs).

A CCL intercomparison (CCL-K5) was performed. At its meeting in 2003, the APMP Technical Committee Length decided that a new key comparison on step gauge measurements shall be carried out. Both the CCL and the Regional comparisons will establish equivalence with National Metrology Institutes throughout the world.

In September 2003, CCL 11 decided to introduce some changes in future Key Comparisons by having interregional participation organized through the Regional Technical Committees for Length (RTCLs) and the WGDM, so leaving the regions in charge of their comparisons but bringing the CCL/WGDM into the loop to be able to monitor and negotiate any difficulties. So NMIs of other regions as well as APMP were invited to participate this comparison

2 Organization

This technical protocol is modelled on the previous protocols for CCL-K5 drawn by the Physikalisch-Technische Bundesanstalt (PTB), Germany and for EUROMET.L-K5 drawn by the Centro Español de Metrología (CEM). The technical protocol was issued to all participants at the start of the comparison.

The procedures outlined in this document cover the technical procedure to be followed during measurement of the step gauge. The procedure follows the guidelines established by the BIPM1.

2. 1 Participants

As previously stated in the Introduction, the list of participants has been taken from the APMP members and from other regions members through WGDM members.

All participants must be able to demonstrate independent traceability to the realization of the metre.

There is an additional requirement to measure the artefacts at a temperature sufficiently close to 20 °C that the uncertainty in the measured expansion coefficient does not dominate the overall measurement uncertainty.

By their declared intention to participate in this key comparison, the laboratories accept the general instructions and the technical protocol written down in this document and commit themselves to follow the procedures strictly.

Once the list of participants has been agreed, no change to the participants could be made prior agreement of all participants. During the comparison contact persons of NMIs were changed.

1 T.J. Quinn, Guidelines for key comparisons carried out by Consultative Committees, BIPM, Paris


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Participants’ details APMP:

Contact Person

National Metrology Institute Address

Tel. Fax e-mail:

Gao Sitian National Institute of Metrology Beisanhuandonglu 18, 100013 Beijing China

Tel: + 86 10 64211631-2107 Fax:+ 0086 10 84251574 email:[email protected]

S.Y.Wong SCL 36 F, Immigration Tower, 7 Gloucester Road, Wan Chai Hong Kong

Tel: 852- 28294805 Fax:852- 28241302 email:sywong @itc.gov.hk

K.P. Chaudhary National Physical Laboratory, Dr. K S Krishnan Marg, New Delhi-110012 India.

Tel: + 91-11-45608673 Fax:+ 91-11-45608673 [email protected]

A. Praba Drijarkara

Puslit KIM-LIPI Bld. 420, Kompleks Puspiptek Serpong, Tangerang 15314 Banten Indonesia

Tel: +62-21-7560533x3070 Fax:+62-21-7560568 email:[email protected]

Eleanor Howick IRL/MSL Measurement Standards Laboratory Industrial Research, Gracefield Road PO Box 31-310, Lower Hutt New Zealand

Tel: ++64 4 931 3530 Fax:+ 64 4 931 3117 email:[email protected]

Anusom Tonmeanwai

NMIT

3/4-5 Moo 3, Klong 5, Klong Luang, Pathumthani 10120,

Thailand

Tel.: 662 5775100 Fax.: 662 5773658

email:[email protected]

SHAN-PENG PAN

National Metrology Institute(NMI) CMS-SDI Bldg. 8, 321 Kuang Fu Rd., Sec. 2, Hsinchu Taiwan 300, R.O.C.

Tel.:+886-3-5743759 Fax:+886-3-5726445 e-mail: [email protected]

TAKATSUJI Toshiyuki

National Metrology Institute of Japan (NMIJ/AIST) AIST Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563 Japan

Tel: +81-29-861-4041, Fax :+81-29-861-4042 email:[email protected]

Peter Cox National Measurement Institute Location: Bradfield Rd, West Lindfield, (Sydney) NSW 2070 Australia

Tel: + 61 2 8467 3600 Fax:+ 61 2 8467 3610 email:[email protected]


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EURAMET:

Rudolf Thalmann

Federal Office of Metrology (METAS), Lindenweg 50 CH-3003 Bern-Wabern Switzerland

Tel: +41 31 32 33 385 Fax:+41 31 32 33 210 email:Rudolf.Thalmann@

metas.ch SIM:

João Antônio Pires Alves

INMETRO - National Institute of Metrology, Standardization and Industrial Quality Av. N. Sra. das Graças, 50 Vila Operária - Xerém - Duque de Caxias - R. J. CEP: 25250-020 Brazil

Tel.: 005521-26799036 Fax: 005521-26791505 email: [email protected]

John Stoup NIST Metrology (220) Room B113, 100 Bureau Drive, Stop 8211 Gaithersburg, MD, 20899-8211 USA

Tel : + 1 301 975 3476 Fax: + 1 301 869 0822 email:[email protected]

Pilot:

Taebong Eom KRISS Korea Research Institute of Standards and Science, 1 Doryong-dong, Yuseong-gu, Daejeon, 305-340, Rep of Korea

Tel : +82 42 868 5100 Fax: +82 42 868 5608 email: [email protected]

2.2 Form of comparison The comparison will be conducted in three stages with each stage starting and finishing at the pilot laboratory. The first and second stages will be for APMP and the third for other RMOs. One NMI in APMP was shifted to the third stage because of problem of step gauge measuring system.

KRISS will act as the pilot laboratory. All results are to be communicated directly to the pilot laboratory as soon as possible and certainly within 6 weeks of completion of the measurements by a laboratory.

The stability of the step gauge will be assessed by measurements made at KRISS before and during the circulation of the step gauge.

Each laboratory will receive the step gauge in turn, according to the pre-agreed timetable. A final set of measurements will be made at the end of the comparison by the pilot laboratory.

Each laboratory has one month for calibration and transportation. With its confirmation to participate, each laboratory has confirmed that it is capable of performing the measurements in the time allocated to it. It guarantees that the standards arrive in the country of the next participant at the beginning of the next month.

If for some reasons, the measurement facility is not ready or customs clearance takes too much time in a country, the laboratory has to contact the pilot laboratory immediately and – according to the arrangement made - eventually to send the standard directly to the next


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participant before finishing the measurements or even without doing any measurements. If possible the laboratory will be sent the artefact at the end of the comparison.

2.3 Time Schedule

Comparison lasted from December 2005 to December 2007. There were some delays because of custom clearance and wrong transportation. The last measurement result of one participant was received on January 2009.

PTB withdrew to participate because PTB did not provide the calibration service for the step gauge no more. And one NMI in APMP was shifted to the third stage because of problem of step gauge measuring system.

Region NMI(code) Date Remark

APMP KRISS(A) December 05

NMIJ(B) January 06

NMIA(C) February 06

NMIT(D) March 06

NPLI(E) May 06

KRISS(A) June 06

CMS-SDI(F) July 06

KIM/LIPI(G) August 06

NIM(H) November 06

SIM INMETRO(I) December 06

APMP KRISS(A) February 07

IRL/MSL(J) March 07

EURAMET PTB widthrawn

METAS(K) April 07

SIM NIST(L) June 07

APMP SCL(M) September 07 Schedule changed

KRISS(A) December 07

Table 1. Timetable of the comparison.


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2.4 Handling and transport of the artefact

The step gauge should be examined immediately upon receipt. The condition of the step gauge should be noted and communicated to the pilot laboratory.

The step gauge should only be handled by authorised persons and stored in such a way as to prevent damage.

The step gauge should be examined before despatch and any change in condition during the measurement at each laboratory should be communicated to the pilot laboratory. Laboratories should inform the pilot laboratory and the next laboratory via fax or e-mail when the step gauge is about to be sent to the next recipient. But A few laboratories did not communicate to the pilot laboratory on receiving the artifact and sending the artifact to next laboratory.

It is very important that the step gauge be transported in a manner in which it will not be lost, damaged or handled by un-authorised persons. The step gauge will be stored in an aluminium storage box, and the storage box is stored in a wooden shipping container.

Packaging for the artefact has been made which will be suitably robust to protect the artefacts from being deformed or damaged during transit.

The step gauge should be sent via courier or delivery company. It should be marked as ‘Fragile’ and ‘Handle with care’.

The step gauge should be accompanied by an ATA carnet (where appropriate) or documentation identifying the items uniquely. The packaging is lockable e.g. by clasp, but is easy to open with minimum delay to allow customs inspections to take place.

Transportation is each laboratory’s responsibility and cost. Each participating laboratory covers the costs for its own measurements, transportation and any customs charges as well as for any damages that may have occurred within its country. The overall costs for the organisation and for the devices are covered by the organising pilot laboratory. The pilot laboratory has no insurance for any loss or damage of the standard during transportation.

The artefact had been sent to wrong country because of mistake of delivery company. It also was a reason for delay comparison.


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3 Description of the Standard

3.1 Artefact

The measurement artefact is a step-gauge KOBA, having a steel frame, 16 ceramic gauges, and 620 mm nominal length. The thermal expansion coefficient is α = 11.5 × 10-6 K-1 (Serial No. :200412 S232, 20 mm steps, 32 contact faces, Manufacture : KOLB & BAUMANN GmbH & Co)

This step gauge is a same type circulated at CCL-K5 Comparison. At CCL-K5, the step gauge was stable over comparison.

The step gauge used for this comparison is provided by NMIJ .

Fig.1 Drawing of the KOBA step-gauge


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3.2 Damage

During the circulation, serious damage was not found at artifact. At arrival at pilot laboratory after 2nd stage comparison, one buckle of the wooden box was torn off.

4 Measurement instructions

4.1 Traceability

Length measurements should be independently traceable to the latest realisation of the metre as set out in the current ”Mise en Pratique”.

Temperature measurements should be made using the International Temperature Scale of 1990 (ITS-90).

4.2 Measurands

The measurands of the step gauge are the 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. The measurements shall be carried out as much as possible near the centres of the front faces of the gauges or along an axis which passes through the centre of the measuring face No. 0 and is parallel to both the bottom face and the side alignment face.

The thermal expansion coefficient indicated for the artefact should be used by Laboratories when measuring the artefact. Laboratories should report the temperatures at which the length measurements were made. Laboratories should only measure the artefact at a temperature close to 20 °C.

4.3 Measurement instructions

The goal of this APMP comparison is to demonstrate the equivalence of routine calibration service for step gauge measurements offered by NMIs to clients, as listed by them in Appendix C of the BIPM Mutual Recognition Agreement (MRA). To this end, participants in this comparison agree to use the same apparatus and methods as routinely applied when calibrating artefacts for clients. Participants are free to tune and operate their systems to best-measurement performance and to take any extra measurements needed to produce a best measurement result, provided that these extra efforts would also be available to a client if requested.

Before calibration, the step gauge must be inspected for damage to the measurement surfaces and side faces. Any scratches, rusty spots or other damages have to be documented.

The alignment of the step gauge will be done by using the bottom face of the groove where the gauges are fixed and the side-walls. If a different alignment procedure is preferred by your laboratory or needed because of equipment constraints then please document it together with the results. The step-gauge should be supported in the Bessel points.

The measurement results have to be appropriately corrected to the reference temperature of 20 °C using the values of the thermal expansion coefficient provided.


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No other measurements are to be attempted by the participants and the step gauge should not be used for any purpose other than described in this document. The artefact may not be given to any party other than the participants in the comparison.

If for any reason a laboratory is not able to measure all positions of gauges on the step, it is still encouraged to report as much results as it can.

4.4 Inspection of the artefact

Before calibration, the artefact must be inspected for damage to the measurement surfaces and side faces. Any scratches, rusty spots or other damages had to be documented.

4.5 Alignment

The alignment of the step gauge should be done by using the bottom face of the groove where the gauges are fixed and the side-walls. If a different alignment procedure was preferred by the laboratory or needed because of equipment constraints, documentation was requested together with the results. The step-gauge should be supported in the Bessel points marked in the step gauge.

4.6 Thermal expansion correction The measurement results had to be appropriately corrected to the reference temperature of 20 °C using the values of the thermal expansion coefficient provided.

4.7 Reporting of incomplete data If for any reason a laboratory were not able to measure all positions of gauges on the step, it was still encouraged to report as much results as it could. One NMI did not report the data of one measuring surface in this comparison.


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5 Stability of the step gauge

Four calibrations were performed by a pilot laboratory in December 2005, June 2006, February 2007 and December 2007. The following graph shows the difference from data of Dec. 2005. Significant change was not observed during comparison. The observed differences were smaller than the measurement uncertainty of pilot. For further analysis and determination of reference value, the data of December 2005 was used as data of pilot.

-0.20

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Face

Devi

atio

n(u

m)

Dec 05 - Jun 06 Dec 05 - Feb 07 Dec 05 - Dec 07

Fig.2 Difference between pilot calibrations of step gauge from Dec. 2005 to Dec. 2007.

6 Measurement results

All participants reported the measurement data. (One NMI did not report the data of one measuring face.)

To avoid complexity in the graphs and tables along the Report, a code has been used to identify the participants, instead of using the full name of the laboratory.

(unit : mm)

Face KRISS (Lab A)

NMIJ (Lab B)

NMIA (Lab C)

NMIT (Lab D)

NPLI (Lab E)

CMS-SDI (Lab F)

KIM/LIPI (Lab G)

0 – 1 20.00009 20.00011 19.99978 19.99982 20.0002 19.99984 19.9990 0 – 2 39.99077 39.99081 39.99083 39.99049 39.9915 39.99062 39.9911 0 – 3 59.99137 59.99138 59.99123 59.99108 59.9917 59.99101 59.9907 0 – 4 80.01635 80.01633 80.01629 80.01604 80.0165 80.01621 80.0172 0 – 5 100.01641 100.01638 100.01616 100.01613 100.0167 100.01609 100.0167 0 – 6 119.99801 119.99798 119.99807 119.99768 119.9989 119.99795 119.9989 0 – 7 139.99825 139.99816 139.99794 139.99789 139.9986 139.99791 139.9979


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0 – 8 160.10439 160.10438 160.10448 160.10409 160.1051 160.10437 160.1055 0 – 9 180.10590 180.10577 180.10561 180.10552 180.1062 180.10536 180.1056

0 – 10 200.00031 200.00028 200.00048 199.99999 200.0013 200.00021 200.0013 0 – 11 220.00189 220.00176 220.00170 220.00155 220.0024 220.00149 220.0014 0 – 12 240.06316 240.06305 240.06323 240.06273 240.0640 240.06300 240.0641 0 – 13 260.06322 260.06302 260.06300 260.06279 260.0639 260.06272 260.0630 0 – 14 280.01447 280.01429 280.01464 280.01406 280.0153 280.01425 280.0159 0 – 15 300.01471 300.01449 300.01442 300.01427 300.0151 300.01415 300.0149 0 – 16 320.06200 320.06182 320.06210 320.06150 320.0626 320.06180 320.0634 0 – 17 340.06182 340.06154 340.06163 340.06127 340.0629 340.06122 340.0618 0 – 18 359.99369 359.99354 359.99381 359.99322 359.9948 359.99356 359.9953 0 – 19 379.98821 379.98778 379.98792 379.98753 379.9888 379.98753 379.9899 0 – 20 399.96418 399.96403 399.96427 399.96370 399.9660 399.96405 399.9659 0 – 21 419.95833 419.95806 419.95811 419.95778 419.9592 419.95789 419.9592 0 – 22 440.00285 440.00265 440.00304 440.00239 440.0039 440.00271 440.0047 0 – 23 459.99776 459.99739 459.99758 459.99719 459.9984 459.99726 459.9986 0 – 24 480.07459 480.07442 480.07493 480.07400 480.0756 480.07461 N/A 0 – 25 500.06919 500.06882 500.06887 500.06846 500.0705 500.06877 500.0705 0 – 26 520.07540 520.07514 520.07561 520.07488 520.0765 520.07546 520.0774 0 – 27 540.07013 540.06966 540.06977 540.06944 540.0714 540.06975 540.0711 0 – 28 560.01167 560.01135 560.01187 560.01106 560.0127 560.01165 560.0136 0 – 29 580.00652 580.00605 580.00621 580.00584 580.0074 580.00613 580.0076 0 – 30 600.06434 600.06405 600.06453 600.06227 600.0654 600.06442 600.0664 0 – 31 620.05943 620.05899 620.05920 620.05877 620.0610 620.05912 620.0602

Face NIM (Lab H)

INMETRO (Lab I)

IRL/MSL (Lab J)

METAS (Lab K)

NIST (Lab L)

SCL (Lab M)

0 – 1 19.99998 20.00008 20.00011 20.00004 20.000148 19.99914 0 – 2 39.99093 39.99085 39.99077 39.99085 39.990785 39.99101 0 – 3 59.99135 59.99131 59.99140 59.99137 59.991405 59.99068 0 – 4 80.01645 80.01639 80.01630 80.01640 80.016328 80.01651 0 – 5 100.01638 100.01630 100.01640 100.01639 100.016424 100.01556 0 – 6 119.99811 119.99811 119.99801 119.99809 119.997990 119.99809 0 – 7 139.99817 139.99817 139.99826 139.99822 139.998207 139.99742 0 – 8 160.10460 160.10450 160.10462 160.10452 160.104441 160.10443 0 – 9 180.10587 180.10573 180.10608 180.10584 180.105865 180.10418

0 – 10 200.00055 200.00040 200.00060 200.00044 200.000347 199.99969 0 – 11 220.00188 220.00181 220.00212 220.00187 220.001843 220.00017 0 – 12 240.06342 240.06321 240.06344 240.06328 240.063150 240.06245 0 – 13 260.06320 260.06307 260.06342 260.06316 260.063160 260.06167 0 – 14 280.01477 280.01453 280.01479 280.01460 280.014482 280.01381 0 – 15 300.01468 300.01451 300.01494 300.01466 300.014656 300.01258


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0 – 16 320.06225 320.06204 320.06228 320.06210 320.061951 320.06083 0 – 17 340.06176 340.06163 340.06194 340.06174 340.061729 340.05938 0 – 18 359.99404 359.99382 359.99393 359.99387 359.993698 359.99224 0 – 19 379.98813 379.98798 379.98813 379.98803 379.987989 379.98559 0 – 20 399.96449 399.96430 399.96440 399.96434 399.964184 399.96287 0 – 21 419.95836 419.95819 419.95843 419.95830 419.958270 419.95590 0 – 22 440.00313 440.00290 440.00308 440.00302 440.002818 440.00142 0 – 23 459.99781 459.99754 459.99786 459.99769 459.997622 459.99539 0 – 24 480.07492 480.07467 480.07499 480.07481 480.074615 480.07339 0 – 25 500.06928 500.06895 500.06941 500.06914 500.069054 500.06694 0 – 26 520.07573 520.07548 520.07582 520.07559 520.075359 520.07420 0 – 27 540.07011 540.06988 540.07031 540.07004 540.069908 540.06781 0 – 28 560.01196 560.01166 560.01201 560.01182 560.011570 560.01047 0 – 29 580.00651 580.00630 580.00670 580.00646 580.006321 580.00439 0 – 30 600.06477 600.06445 600.06470 600.06455 600.064285 600.06332 0 – 31 620.05948 620.05931 620.05962 620.05940 620.059265 620.05741

Table 2 Measurement results.

7 Measurement uncertainty

The technical protocol specified that the uncertainty of measurement should be estimated according to the ISO Guide to the Expression of Uncertainty in Measurement. Typical uncertainties (1σ ) reported by the participants, present the following table.

(unit : µm)

Face KRISS NMIJ NMIA NMIT NPLI CMS-SDI

KIM/ LIPI NIM INME

TRO IRL/ MSL

METAS NIST SCL

0 – 1 0.17 0.19 0.14 0.200 0.52 0.22 0.62 0.09 0.16 0.27 0.080 0.058 0.31

0 – 2 0.17 0.19 0.14 0.202 0.53 0.22 0.44 0.09 0.16 0.22 0.080 0.060 0.3

0 – 3 0.17 0.19 0.15 0.204 0.55 0.22 0.62 0.09 0.16 0.26 0.080 0.062 0.34

0 – 4 0.18 0.20 0.15 0.207 0.56 0.22 0.44 0.1 0.16 0.27 0.080 0.064 0.34

0 – 5 0.18 0.20 0.15 0.211 0.58 0.23 0.62 0.1 0.16 0.25 0.080 0.066 0.4

0 – 6 0.18 0.21 0.15 0.216 0.60 0.23 0.45 0.11 0.17 0.32 0.085 0.068 0.41

0 – 7 0.19 0.22 0.16 0.221 0.61 0.24 0.63 0.11 0.17 0.28 0.085 0.070 0.47

0 – 8 0.20 0.22 0.16 0.227 0.63 0.25 0.45 0.12 0.17 0.35 0.090 0.072 0.49

0 – 9 0.20 0.23 0.17 0.234 0.64 0.25 0.63 0.13 0.17 0.28 0.090 0.074 0.55

0 – 10 0.21 0.24 0.17 0.241 0.66 0.26 0.46 0.13 0.17 0.36 0.090 0.076 0.57

0 – 11 0.22 0.25 0.18 0.248 0.68 0.27 0.64 0.14 0.17 0.3 0.095 0.078 0.63

0 – 12 0.22 0.26 0.18 0.257 0.69 0.28 0.47 0.15 0.17 0.38 0.095 0.080 0.66


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0 – 13 0.23 0.27 0.19 0.265 0.71 0.29 0.64 0.16 0.17 0.31 0.100 0.082 0.72

0 – 14 0.24 0.28 0.19 0.274 0.72 0.3 0.47 0.16 0.17 0.38 0.105 0.084 0.75

0 – 15 0.25 0.30 0.20 0.284 0.74 0.31 0.65 0.17 0.17 0.31 0.105 0.086 0.81

0 – 16 0.26 0.31 0.21 0.293 0.76 0.32 0.48 0.18 0.18 0.39 0.110 0.088 0.85

0 – 17 0.27 0.32 0.22 0.303 0.77 0.33 0.66 0.19 0.18 0.33 0.110 0.090 0.9

0 – 18 0.27 0.33 0.22 0.313 0.79 0.34 0.5 0.2 0.18 0.4 0.115 0.092 0.94

0 – 19 0.28 0.35 0.23 0.324 0.80 0.36 0.66 0.21 0.18 0.33 0.120 0.094 1

0 – 20 0.29 0.36 0.24 0.334 0.82 0.37 0.5 0.22 0.18 0.4 0.125 0.096 1.04

0 – 21 0.30 0.37 0.24 0.345 0.84 0.38 0.8 0.22 0.18 0.34 0.125 0.098 1.09

0 – 22 0.31 0.38 0.25 0.356 0.85 0.39 0.67 0.23 0.35 0.42 0.130 0.100 1.14

0 – 23 0.32 0.40 0.26 0.367 0.87 0.41 0.8 0.24 0.35 0.36 0.135 0.102 1.19

0 – 24 0.33 0.41 0.27 0.379 0.88 0.42 N/A 0.25 0.35 0.42 0.140 0.104 1.23

0 – 25 0.34 0.42 0.28 0.390 0.90 0.43 0.8 0.26 0.35 0.36 0.140 0.106 1.29

0 – 26 0.36 0.44 0.28 0.402 0.92 0.44 0.68 0.27 0.35 0.42 0.145 0.108 1.33

0 – 27 0.37 0.45 0.29 0.413 0.93 0.46 0.81 0.28 0.35 0.39 0.150 0.110 1.39

0 – 28 0.38 0.47 0.30 0.425 0.95 0.47 0.68 0.29 0.35 0.45 0.155 0.112 1.43

0 – 29 0.39 0.48 0.31 0.437 0.96 0.48 0.81 0.3 0.35 0.41 0.155 0.114 1.48

0 – 30 0.40 0.49 0.32 0.449 0.98 0.5 0.68 0.31 0.35 0.47 0.160 0.116 1.53

0 – 31 0.41 0.51 0.33 0.461 1.00 0.51 0.81 0.32 0.35 0.47 0.165 0.118 1.58

Table 3 Measurement uncertainties.

8 Analysis of the reported results 8.1 Simple mean data reference First of all, to visualize the measurement data, the simple mean was applied. The result is shown in Fig. 3. It is obvious that data of 3 NMIs(NPLI, KIM/LIPI and SCL) have the systematic errors and one measuring face(face 30) data of NMIT will be outlier.


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Difference to simple mean

-3

-2

-1

0

1

2

3

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Face

Deffere

nce(㎛

)

A B C D E F G H I J K L M

Fig.3 Measurement data vs. simple mean

8.2 Weighted mean data reference

In order to analyze the measurement data, Excel Toolkits developed by NRC (Canada) was used.

Table 4 show the deviation from the weighted mean determined by Excel Toolkits and participants list with consistency less than 5 %. Here the data with consistency level less than 5 % are not excluded on determining the weighted mean. Many faces data of SCL and KIM/LIPI and some faces data of a few of laboratory do not pass the consistency test. Most of data of NPLI, while it has the systematic error similar to KIM/LIPI, have larger uncertainties and pass the consistency test.

Face Weighted

mean(µm) Difference from weighted mean(Lab value – mean value, µm)

KRISS NMIJ NMIA NMIT NPLI CMS-SDI

0 – 1 20000.036 0.054 0.074 -0.256 -0.216 0.164 -0.196

0 – 2 39990.821 -0.051 -0.011 0.009 -0.331 0.679 -0.201

0 – 3 59991.340 0.030 0.040 -0.110 -0.260 0.360 -0.330

0 – 4 80016.359 -0.009 -0.029 -0.069 -0.319 0.141 -0.149

0 – 5 100016.359 0.051 0.021 -0.199 -0.229 0.341 -0.269

0 – 6 119998.041 -0.031 -0.061 0.029 -0.361 0.859 -0.091

0 – 7 139998.162 0.088 -0.002 -0.222 -0.272 0.438 -0.252

0 – 8 160104.480 -0.090 -0.100 0.000 -0.390 0.620 -0.110

0 – 9 180105.800 0.100 -0.030 -0.190 -0.280 0.400 -0.440

0 – 10 200000.398 -0.088 -0.118 0.082 -0.408 0.902 -0.188

0 – 11 220001.818 0.072 -0.058 -0.118 -0.268 0.582 -0.328

0 – 12 240063.211 -0.051 -0.161 0.019 -0.481 0.789 -0.211


16/35

0 – 13 260063.121 0.099 -0.101 -0.121 -0.331 0.779 -0.401

0 – 14 280014.546 -0.076 -0.256 0.094 -0.486 0.754 -0.296

0 – 15 300014.605 0.105 -0.115 -0.185 -0.335 0.495 -0.455

0 – 16 320062.030 -0.030 -0.210 0.070 -0.530 0.570 -0.230

0 – 17 340061.693 0.127 -0.153 -0.063 -0.423 1.207 -0.473

0 – 18 359993.784 -0.094 -0.244 0.026 -0.564 1.016 -0.224

0 – 19 379987.996 0.214 -0.216 -0.076 -0.466 0.804 -0.466

0 – 20 399964.269 -0.089 -0.239 0.001 -0.569 1.731 -0.219

0 – 21 419958.246 0.084 -0.186 -0.136 -0.466 0.954 -0.356

0 – 22 440002.913 -0.063 -0.263 0.127 -0.523 0.987 -0.203

0 – 23 459997.635 0.125 -0.245 -0.055 -0.445 0.765 -0.375

0 – 24 480074.691 -0.101 -0.271 0.239 -0.691 0.909 -0.081

0 – 25 500069.074 0.116 -0.254 -0.204 -0.614 1.426 -0.304

0 – 26 520075.481 -0.081 -0.341 0.129 -0.601 1.019 -0.021

0 – 27 540069.953 0.177 -0.293 -0.183 -0.513 1.447 -0.203

0 – 28 560011.699 -0.029 -0.349 0.171 -0.639 1.001 -0.049

0 – 29 580006.369 0.151 -0.319 -0.159 -0.529 1.031 -0.239

0 – 30 600064.381 -0.041 -0.331 0.149 -2.111 1.019 0.039

0 – 31 620059.314 0.116 -0.324 -0.114 -0.544 1.686 -0.194

Face Difference from weighted mean(Lab value – mean value, µm) Lab.

consistency of

less than 5 %KIM/LIPI NIM INMETR

O IRL/MSL METAS NIST SCL

0 – 1 -1.036 -0.056 0.044 0.074 0.004 0.112 -0.896 L, M

0 – 2 0.279 0.109 0.029 -0.051 0.029 -0.036 0.189

0 – 3 -0.640 0.010 -0.030 0.060 0.030 0.065 -0.660

0 – 4 0.841 0.091 0.031 -0.059 0.041 -0.031 0.151

0 – 5 0.341 0.021 -0.059 0.041 0.031 0.065 -0.799

0 – 6 0.859 0.069 0.069 -0.031 0.049 -0.051 0.049

0 – 7 -0.262 0.008 0.008 0.098 0.058 0.045 -0.742

0 – 8 1.020 0.120 0.020 0.140 0.040 -0.039 -0.050 G

0 – 9 -0.200 0.070 -0.070 0.280 0.040 0.065 -1.620 M

0 – 10 0.902 0.152 0.002 0.202 0.042 -0.051 -0.708 G

0 – 11 -0.418 0.062 -0.008 0.302 0.052 0.025 -1.648 M

0 – 12 0.889 0.209 -0.001 0.229 0.069 -0.061 -0.761

0 – 13 -0.121 0.079 -0.051 0.299 0.039 0.039 -1.451 M

0 – 14 1.354 0.224 -0.016 0.244 0.054 -0.064 -0.736 D, G

0 – 15 0.295 0.075 -0.095 0.335 0.055 0.051 -2.025 M

0 – 16 1.370 0.220 0.010 0.250 0.070 -0.079 -1.200 D, G

0 – 17 0.107 0.067 -0.063 0.247 0.047 0.036 -2.313 M

0 – 18 1.516 0.256 0.036 0.146 0.086 -0.086 -1.544 D, G

0 – 19 1.904 0.134 -0.016 0.134 0.034 -0.007 -2.406 G, M

0 – 20 1.631 0.221 0.031 0.131 0.071 -0.085 -1.399 D,E, G, L

0 – 21 0.954 0.114 -0.056 0.184 0.054 0.024 -2.346 M

0 – 22 1.787 0.217 -0.013 0.167 0.107 -0.095 -1.493 G

0 – 23 0.965 0.175 -0.095 0.225 0.055 -0.013 -2.245

0 – 24 0.000 0.229 -0.021 0.299 0.119 -0.076 -1.301


17/35

0 – 25 1.426 0.206 -0.124 0.336 0.066 -0.020 -2.134

0 – 26 1.919 0.249 -0.001 0.339 0.109 -0.122 -1.281 G

0 – 27 1.147 0.157 -0.073 0.357 0.087 -0.045 -2.143

0 – 28 1.901 0.261 -0.039 0.311 0.121 -0.129 -1.229 G

0 – 29 1.231 0.141 -0.069 0.331 0.091 -0.048 -1.979

0 – 30 2.019 0.389 0.069 0.319 0.169 -0.096 -1.061 D,G,H,K,L

0 – 31 0.886 0.166 -0.004 0.306 0.086 -0.049 -1.904

Table 4 Deviation from weighted mean and participants list with consistency less than 5 %


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Fig. 4 Measurement data of participants vs. weighted mean (unit : µm)

Face 1(20 mm)

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Face 12(240 mm)

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Face 17(340 mm)

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Face 18(360 mm)

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Face 19(380 mm)

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Face 24(480 mm)

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Face 30(600 mm)

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Fig. 5 Deviation to the weighted mean of the 31 faces of the step gauge (unit : µm)

8.3 Weighted mean data reference, excluding outliers As shown in Fig. 3, data of NPLI, KIM/LIPI and SCL have the systematic errors and also face 30 data of NMIT shows the obvious error. Additionally, some data of KIM/LIPI, SCL, NMIT and NPLI are not consistent at the 5 % level on checking for consistency. After feedback from many of the laboratories it was decide to exclude four laboratories, NPLI, KIM/LIPI and SCL on all faces data and NMIT on the face 30 data. Table 5 show the deviation from the weighted mean determined by Excel Toolkits by skipping data sets of NPLI, KIM/LIPI and SCL and face 30 data of NMIT. The result can be seen in table 5 and Fig. 6. The data sets of Fig. 6 match better than in Fig. 3.

Face

Weighted

mean(µm) Difference from weighted mean(Lab value – mean value, µm)

KRISS NMIJ NMIA NMIT NPLI CMS-SDI

0 – 1 20000.051 0.039 0.059 -0.271 -0.231 0.149 -0.211

0 – 2 19990.813 -0.043 -0.003 0.017 -0.323 0.687 -0.193

0 – 3 59991.347 0.023 0.033 -0.117 -0.267 0.353 -0.337

0 – 4 80016.350 0.000 -0.020 -0.060 -0.310 0.150 -0.140

0 – 5 100016.364 0.046 0.016 -0.204 -0.234 0.336 -0.274

0 – 6 119998.030 -0.020 -0.050 0.040 -0.350 0.870 -0.080

0 – 7 139998.167 0.083 -0.007 -0.227 -0.277 0.433 -0.257

0 – 8 160104.469 -0.079 -0.089 0.011 -0.379 0.631 -0.099

0 – 9 180105.809 0.091 -0.039 -0.199 -0.289 0.391 -0.449

0 – 10 200000.390 -0.080 -0.110 0.090 -0.400 0.910 -0.180

0 – 11 220001.827 0.063 -0.067 -0.127 -0.277 0.573 -0.337

0 – 12 240063.202 -0.042 -0.152 0.028 -0.472 0.798 -0.202

0 – 13 260063.125 0.095 -0.105 -0.125 -0.335 0.775 -0.405

0 – 14 280014.530 -0.060 -0.240 0.110 -0.470 0.770 -0.280

0 – 15 300014.609 0.101 -0.119 -0.189 -0.339 0.491 -0.459

0 – 16 320062.015 -0.015 -0.195 0.085 -0.515 0.585 -0.215

0 – 17 340061.694 0.126 -0.154 -0.064 -0.424 1.206 -0.474

0 – 18 359993.765 -0.075 -0.225 0.045 -0.545 1.035 -0.205

0 – 19 379987.985 0.225 -0.205 -0.065 -0.455 0.815 -0.455

0 – 20 399964.241 -0.061 -0.211 0.029 -0.541 1.759 -0.191

0 – 21 419958.243 0.087 -0.183 -0.133 -0.463 0.957 -0.353

0 – 22 440002.896 -0.046 -0.246 0.144 -0.506 1.004 -0.186

0 – 23 459997.631 0.129 -0.241 -0.051 -0.441 0.769 -0.371

0 – 24 480074.690 -0.100 -0.270 0.240 -0.690 0.910 -0.080

0 – 25 500069.062 0.128 -0.242 -0.192 -0.602 1.438 -0.292

0 – 26 520075.458 -0.058 -0.318 0.152 -0.578 1.042 0.002

0 – 27 540069.937 0.193 -0.277 -0.167 -0.497 1.463 -0.187

0 – 28 560011.673 -0.003 -0.323 0.197 -0.613 1.027 -0.023


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0 – 29 580006.349 0.171 -0.299 -0.139 -0.509 1.051 -0.219

0 – 30 600064.415 -0.075 -0.365 0.115 -2.145 0.985 0.005

0 – 31 620059.296 0.134 -0.306 -0.096 -0.526 1.704 -0.176

Face Difference from weighted mean(Lab value – mean value, µm)

KIM/LIPI NIM INMETRO IRL/MSL METAS NIST SCL

0 – 1 -1.051 -0.071 0.029 0.059 -0.011 0.097 -0.911

0 – 2 0.287 0.117 0.037 -0.043 0.037 -0.028 0.197

0 – 3 -0.647 0.003 -0.037 0.053 0.023 0.058 -0.667

0 – 4 0.850 0.100 0.040 -0.050 0.050 -0.022 0.160

0 – 5 0.336 0.016 -0.064 0.036 0.026 0.060 -0.804

0 – 6 0.870 0.080 0.080 -0.020 0.060 -0.040 0.060

0 – 7 -0.267 0.003 0.003 0.093 0.053 0.040 -0.747

0 – 8 1.031 0.131 0.031 0.151 0.051 -0.028 -0.039

0 – 9 -0.209 0.061 -0.079 0.271 0.031 0.056 -1.629

0 – 10 0.910 0.160 0.010 0.210 0.050 -0.043 -0.700

0 – 11 -0.427 0.053 -0.017 0.293 0.043 0.016 -1.657

0 – 12 0.898 0.218 0.008 0.238 0.078 -0.052 -0.752

0 – 13 -0.125 0.075 -0.055 0.295 0.035 0.035 -1.455

0 – 14 1.370 0.240 0.000 0.260 0.070 -0.048 -0.720

0 – 15 0.291 0.071 -0.099 0.331 0.051 0.047 -2.029

0 – 16 1.385 0.235 0.025 0.265 0.085 -0.064 -1.185

0 – 17 0.106 0.066 -0.064 0.246 0.046 0.035 -2.314

0 – 18 1.535 0.275 0.055 0.165 0.105 -0.067 -1.525

0 – 19 1.915 0.145 -0.005 0.145 0.045 0.004 -2.395

0 – 20 1.659 0.249 0.059 0.159 0.099 -0.057 -1.371

0 – 21 0.957 0.117 -0.053 0.187 0.057 0.027 -2.343

0 – 22 1.804 0.234 0.004 0.184 0.124 -0.078 -1.476

0 – 23 0.969 0.179 -0.091 0.229 0.059 -0.009 -2.241

0 – 24 - 0.230 -0.020 0.300 0.120 -0.075 -1.300

0 – 25 1.438 0.218 -0.112 0.348 0.078 -0.008 -2.122

0 – 26 1.942 0.272 0.022 0.362 0.132 -0.099 -1.258

0 – 27 1.163 0.173 -0.057 0.373 0.103 -0.029 -2.127

0 – 28 1.927 0.287 -0.013 0.337 0.147 -0.103 -1.203

0 – 29 1.251 0.161 -0.049 0.351 0.111 -0.028 -1.959

0 – 30 1.985 0.355 0.035 0.285 0.135 -0.130 -1.095

0 – 31 0.904 0.184 0.014 0.324 0.104 -0.031 -1.886


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Table 5 Deviation from weighted mean calculated without data sets of NPLI, KIM/LIPI and SCL and face 30 data of NMIT

Fig.6 Difference to weighted mean reference (data sets of NPLI, KIM/LIPI and SCL

and face 30 data of NMIT excluded)


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Fig. 7 Measurement data of participants vs. weighted mean reference excluding

outliers (unit : µm)

8.4 Determination of reference values Fig. 8 shows the difference between two reference values, weighted mean reference of all results and weighted mean reference excluding outliers. For all faces, the weighted mean excluding outliers varies from the weighted mean of all results by significantly less than uncertainty of the weighted mean of all results. From this, one participant suggested all results of participants were included in calculating the reference value. However some of participants supported to follow the guide line for determining the reference value and exclude the data having the obvious systematic error.


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Fig. 8 Variation in weighted mean, all data – subset excluding outliers, error bar shows

standard uncertainty of the weighted mean of all data

9 Conclusion

This comparison involved 13 laboratories from 3 different metrological regions.

Comparison lasted 2 years from Dec. 2005 to Dec. 2007.

Damage in the step gauge was not observed. And the analysis shows that step gauge was stable during comparison.

For analysis in detail, Excel Toolkits developed by NRC was used to get the reference value. The analysis results are : - A few of participants have the systematic error in measurement.

- The offset on bi-directional probing is not corrected in some data sets.

- Some data of NMIs having good measurement capability are not consistent with the chi-squared null hypothesis test.

For determining the KCRVs, it was decided to exclude four laboratories, NPLI, KIM/LIPI and SCL on all faces data and NMIT on the face 30 data.


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Appendix A : Determination of the reference values

A1.1 Guideline for determination of reference value

At the Workshop on Key Comparison Analysis which took place during the 10th WGDM meeting in 2005, it was agreed to recommend the approach outlined by Maurice Cox in document WDGM-05-86 “Considerations concerning key comparison data evaluation”

The Recommendations of the Consultative Committee for Length (CCL) regarding strategies for evaluating key comparison data, was presented to CCL meeting as discussed at WGDM Workshop. The basic steps for determining the reference values are as below:

A Determine the inverse-variance weighted mean based on the measured values xj and associated standard uncertainties u(xj) submitted by the participants. If no participant provided a (finite) degrees of freedom associated with its declared uncertainty, perform a conventional chi-squared consistency test for this weighted mean and the data. Otherwise, perform an extended chi-squared test.

B a) If the consistency test is satisfied at the 5% level, use the weighted mean as the key comparison reference value (KCRV) and the standard uncertainty associated with it as the standard uncertainty associated with the KCRV.

b) If the consistency check fails at the 5% level do the following.

1 Determine the largest subset of participants’ results that are consistent (at the 5% level) according to the conventional or extended chi-squared test, as appropriate.

Strategy to search for outliers: Successively exclude individual measurement results by, at each stage, selecting that giving the greatest contribution to 2

obsχ and stop when 2χ -test satisfies.

2 The pilot alerts participants whose results are not contained in the largest consistent subset that there may be problems with their data. The participants try to determine technical reasons for the laboratories’ inconsistent results (blunders, inappropriate corrections for systematic effects, method differences, etc).

3 At the discretion of the participants, the pilot could perform additional modelling (e. g. accounting for drift or travelling artefact instability) in order to increase the size of the largest consistent subset;

4 Use the weighted mean of the largest consistent subset as the KCRV and the standard uncertainty associated with it as the standard uncertainty associated with the KCRV.

C Derive unilateral and bilateral degrees of equivalence for all participants, and publish the results of the comparison, providing appropriate advice about using the determined KCRV and the associated standard uncertainty.

For analysis in detail, Excel Toolkits developed by NRC was used to get the reference value. The analysis results are : - A few of participants have the systematic error in measurement.

- The offset on bi-directional probing is not corrected in some data sets.


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- Some data of NMIs having good measurement capability are not consistent with the chi-squared null hypothesis test.

For determining the KCRVs, it was decided to exclude four laboratories, NPLI, KIM/LIPI and SCL on all faces data and NMIT on the face 30 data. Table A1.1 shows the reference values and their standard uncertainties : simple mean,

the weighted mean for all results and weighted mean excluding outliers

(unit : µm)

Face Simple Mean Weighted Mean

Weighted Mean excluding

NPLI, KIM/LIPI, SCL and 30

face of NMIT

Reference Standard

Uncertainty Reference

Standard

Uncertainty Reference

Standard

Uncertainty

0 – 1 19999.872 0.078 20000.036 0.035 20000.051 0.036

0 – 2 39990.870 0.070 39990.821 0.036 39990.813 0.036

0 – 3 59991.230 0.080 59991.340 0.036 59991.347 0.037

0 – 4 80016.408 0.074 80016.359 0.037 80016.350 0.038

0 – 5 100016.310 0.084 100016.359 0.038 100016.364 0.038

0 – 6 119998.145 0.080 119998.041 0.040 119998.030 0.040

0 – 7 139998.084 0.089 139998.162 0.041 139998.167 0.041

0 – 8 160104.571 0.086 160104.480 0.042 160104.469 0.043

0 – 9 180105.656 0.094 180105.800 0.043 180105.809 0.044

0 – 10 200000.454 0.092 200000.398 0.044 200000.390 0.045

0 – 11 220001.683 0.100 220001.818 0.046 220001.827 0.046

0 – 12 240063.248 0.098 240063.211 0.047 240063.202 0.047

0 – 13 260063.025 0.106 260063.121 0.048 260063.125 0.049

0 – 14 280014.607 0.105 280014.546 0.050 280014.530 0.050

0 – 15 300014.467 0.113 300014.605 0.051 300014.609 0.051

0 – 16 320062.052 0.113 320062.030 0.053 320062.015 0.053

0 – 17 340061.566 0.121 340061.693 0.054 340061.694 0.054

0 – 18 359993.809 0.121 359993.784 0.056 359993.765 0.056

0 – 19 379987.963 0.128 379987.996 0.057 379987.985 0.058

0 – 20 399964.363 0.128 399964.269 0.059 399964.241 0.059

0 – 21 419958.155 0.140 419958.246 0.060 419958.243 0.060

0 – 22 440002.970 0.143 440002.913 0.064 440002.896 0.065

0 – 23 459997.546 0.150 459997.635 0.066 459997.631 0.066

0 – 24 480074.629 0.153 480074.691 0.068 480074.690 0.068

0 – 25 500069.068 0.157 500069.074 0.068 500069.062 0.069

0 – 26 520075.582 0.158 520075.481 0.070 520075.458 0.071

0 – 27 540069.947 0.166 540069.953 0.072 540069.937 0.073

0 – 28 560011.799 0.167 560011.699 0.074 560011.673 0.075

0 – 29 580006.349 0.173 580006.369 0.075 580006.349 0.076

0 – 30 600064.422 0.175 600064.381 0.077 600064.415 0.079

0 – 31 620059.323 0.183 620059.314 0.079 620059.296 0.079

Table A1.1 Reference values and their standard uncertainties : simple mean, weighted mean for all results and weighted mean excluding outliers

APMP Regional Comparison (APMP.L-K5) Calibration of Step Gauge€¦ · Beisanhuandonglu 18, 100013...

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