Report on Supplementary Comparison EURAMET.L · PDF filesupplementary comparison on gauge block measurements by mechanical comparison, numbered EURAMET.L ... e-mail: [email protected]

Report on Supplementary Comparison

EURAMET.L-S22

Calibration of gauge blocks by mechanical

comparison

Final report

M.S. Hansen (DTI), A. Lewis (NPL), M. Matus (BEV), J. Hald (DFM), L. Lillepea (Metrosert), E. Prieto (CEM), B. Ačko (MIRS/UM-FS/LTM), R. Hanrahan (NSAI), N. Testa (MCCAA/MSA), Anouar Daoud

(CETIME), L. Švedova (LATMB), L. Gaidamovičiūtė (VMC/VMT), G. Bajic (MBM)

Taastrup, October 2016

EURAMET.L-S22 Calibration of gauge blocks by mechanical comparison Final Report

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Contents 1 Document control ................................................................................................................................ 2

2 Introduction ......................................................................................................................................... 2

3 Organization ......................................................................................................................................... 2

3.1 Participants .................................................................................................................................. 2

3.2 Schedule ....................................................................................................................................... 3

4 Artefacts ............................................................................................................................................... 4

4.1 Description of artefacts ............................................................................................................... 4

4.2 Condition and stability of artefacts ............................................................................................. 5

5 Measuring instructions ........................................................................................................................ 6

5.1 Measurands ................................................................................................................................. 6

6 Results .................................................................................................................................................. 7

6.1 Results and standard uncertainties as reported by participants................................................. 7

6.2 Measurement uncertainties ...................................................................................................... 13

6.3 Changes to results after Draft A.1 ............................................................................................. 14

6.4 Calculation of the SCRV.............................................................................................................. 14

6.5 Calculation of Degrees of Equivalence ...................................................................................... 16

6.6 Discussion of results .................................................................................................................. 18

7 References ......................................................................................................................................... 19

8 Acknowledgments ............................................................................................................................. 19


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1 Document control

Version Draft A.1 Issued on 22 October 2015 Version Draft A.2 Issued on 24 April 2016 Version Draft B1 Issued on 21 July 2016 Version Draft B2 Issued on 31 August 2016 Final Report Sent out 13 October 2016

2 Introduction

The metrological equivalence of national measurement standards and of calibration certificates issued by national metrology institutes is established by a set of key and supplementary comparisons chosen and organized by the Consultative Committees of the CIPM or by the regional metrology organizations in collaboration with the Consultative Committees.

At its meeting in October 2012, the EURAMET Technical Committee for Length, TC-L, decided upon a supplementary comparison on gauge block measurements by mechanical comparison, numbered EURAMET.L-S22, with the Danish Technological Institute (DTI) as the pilot laboratory, assisted by NPL (Andrew Lewis), which would provide a link to CCL-K1. The comparison was registered in February 2013, artefact circulation starts in June 2013 and ended in September 2014.

3 Organization

3.1 Participants

Participants are listed in Table 1.

Table 1. List of participant laboratories and their contacts.

Laboratory Code

Contact person, Laboratory Phone, Fax, email

United Kingdom

NPL Andrew Lewis Hampton Road Teddington Middlesex TW11 OLW England

Tel. +44 20 8943 6074 Fax +44 20 8614 0533 e-mail: [email protected]

Estonia METROSERT Lauri Lillepea AS Metrosert Teaduspargi 8 12618 Tallinn Estonia Replaced by : Holger Kruusla

Tel. +372 681 4810 Fax +372 681 4818 e-mail: [email protected] Tel. +372 681 4803 & +372 5 884 4222 e-mail: [email protected]

Austria BEV Michael Matus BEV Arltgasse 35 1160 Wien Austria

Tel. +43 1 21110-6540 Fax +43 1 21110-6000 e-mail: [email protected]

Spain CEM Emilio Prieto Centro Español de Metrología (CEM) Alfar, 2 – 28760 Tres Cantos (Madrid) Spain

Tel. +34 918074716 Fax +34 918074807 e-mail: [email protected]


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Slovenia MIRS/UM-FS/LTM

Bojan Ačko University of Maribor Faculty of Mechanical Engineering SI-2000 Maribor, Smetanova 17 Slovenia

Tel. +386 2 220 7581 Fax +386 2 220 7586 e-mail: [email protected]

Denmark DTI Maria Svendsmark Hansen (former Holmberg) Gregersensvej 8 2630 Taastrup Denmark

Tel. + 45 7220 3006 Fax + 45 7220 2019 e-mail: [email protected]

Ireland NSAI Paul Turner National Metrology Laboratory Glasnevin Dublin 11 Ireland Replaced by: Rory Hanrahan

Tel. +353 1 8073811 Fax +353 1 8082603 e-mail: [email protected] Tel. +353 1 808 2611 e-mail: [email protected]

Malta MCCAA/MSA Nicola Testa Standards and Metrology Institute Malta Competition and Consumer Affairs Authority Kordin Business Incubation Centre Industrial Estate, Kordin, Paola PLA 3000, MALTA

Tel. + 356 21 242420 e-mail: [email protected]

Tunisia CETIME Anouar Daoud/Chekir Montassar Technical Center of Mechanical and Electrical Industries “CETIME” Z.I. Ksar Said 2086 Douar Hicher La Manouba Tunisia

Tel. +216 70 146 000 / 70 146 023 Fax : +216 70 146 071 / 70 146 070

e-mail: [email protected] [email protected]

Latvia LATMB Larisa Švedova Metrology Bureau (LATMB) K. Valdemara street 157 LV-10113 Riga Latvia

Tel. +371 67517725 e-mail: [email protected]

Denmark DFM Jan Hald DFM A/S Matematiktorvet 307 2800 Lyngby Denmark

Tel. +45 45931144 Fax +45 45931137 e-mail: [email protected]

Lithuania VMC/VMT Lilijana Gaidamovičiūtė JSC ‘Vilnius metrology center’ Dariaus and Girėno str. 23 LT-02189 Vilnius Lithuania

Tel. +85 2306276 Fax. e-mail: [email protected]

Montenegro MBM Gordana Bajic Bureau of Metrology, Laboratory for length measurement Kralja Nikole 2 81000 Podgorica Montenegro

Tel. +382 20 601 360 Fax. +382 20 634 652 e-mail: [email protected]

3.2 Schedule

The comparison started in June 2013 with measurements at NPL (by interferometry and mechanical comparison). The pilot laboratory performed two measurements, one in October 2013 and one in June 2014, where the measurement performed in October 2013 was the official result. Besides from NPL, DFM was also carrying out calibration by interferometry. During the comparison new participants were added, which resulted in a prolonged circulation.


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Schedule and date of preformed measurements are listed in Table 2

Table 2. Schedule of the comparison.

Laboratory Original schedule

Date of measurement

NPL June 2013 June 2013

BEV July 2013 July 2013

METROSERT August 2013 August 2013

LATMB September 2013 September 2013

DTI October 2013 October 2013

CEM October 2013 November 2013

MIRS/UM-FS/LTM December 2013 December 2013

NSAI January 2014 January 2014

MSA/MCCAA February 2014 February 2014

VMC/VMT March 2014 March 2014

MBM April 2014 April 2014

DTI May 2014 June 2014

DFM June 2014 June 2014

CETIME July 2014 August 2014

4 Artefacts

4.1 Description of artefacts

Eight steel gauge blocks were circulated during the comparison. The gauge blocks were supposed to represent ‘typical gauge blocks received from customers’, and thus not necessarily the same quality as normally used in comparisons. The artefacts are listed in Table 3.

Table 3. List of artefacts.

Identification Nominal length

/mm Expansion coefficient

/10-6 K-1 Manufacturer

13643 0.5 11.52 ± 0.5 Tesa

13643 1 11.52 ± 0.5 Tesa

13643 6 11.52 ± 0.5 Tesa

13643 7 11.52 ± 0.5 Tesa

13643 9 11.52 ± 0.5 Tesa

U398 19 11.52 ± 0.5 Tesa

13643 50 11.52 ± 0.5 Tesa

13643 100 11.52 ± 0.5 Tesa


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4.2 Condition and stability of artefacts

All artefacts had scratches and imperfections, and an indentation (probably caused by high measurements force of a stylus) was reported by one laboratory. The rather low quality of the artefacts is expected to have an influence on the results of the participating laboratories, resulting in larger deviations and giving extra contribution to the uncertainty. However, the artefacts used represent typical artefacts as received from customers and thus the outcome of the calibrations should also represent typical deliverance to customers of calibration.

During the circulation of artefacts it was noted that some of the artefacts had engravings that made it impossible for some of the laboratories to report fu and fo values. However, it was concluded that the missing fu and fo values were not critical for the comparison and it was decided that no specific actions should be taken.

The stability of the gauge blocks were evaluated using interferometry (NPL and DFM), as well as two mechanical calibrations performed by DTI. Figure 1 shows deviation from nominal length and expanded uncertainties for the different gauge blocks. No instability was observed for the gauge blocks and difference between deviation for laboratories using interferometry and DTI observed for some gauge blocks is related to the use of different calibration techniques.


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Figure 1. Deviation from nominal length of the gauge blocks with expanded uncertainty bars. NPL and DFM have performed calibration using interferometry, while results from DTI are from mechanical calibration. Please note that the scale bar is not the same on all graphs.

5 Measuring instructions

5.1 Measurands

The gauge blocks shall be measured based on the standard procedure that the laboratory regularly uses for this calibration service for its customers. The “A” surface is the marked measuring face for gauge blocks with nominal length < 6 mm and the right hand measuring face for gauge blocks with a nominal length ≥ 6 mm, respectively (see Figure 2).

Figure 2. Identification of measuring faces ‘A’ and ‘B’.

The mechanical calibration should be performed as a five point measurement and the measurand is as stated in ISO 3650; the deviation of the central length, lc, from the nominal length, ln, thus Δlc=lc-ln. Furthermore, the measurands fo and fu, are defined as in DIN861 where fo=lmax-lc and fu=lc-lmin (see also Figure 3).


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Figure 3. Showing the nominal length, ln, the central length, lc, as well as variation v with fo and fu.

6 Results

6.1 Results and standard uncertainties as reported by participants

Table 4 summarizes the reported deviation from nominal length of gauge blocks.

Table 4. Deviation from nominal length (in m), as reported by the laboratories.

Gauge block nominal length / mm

Lab 0.5 1 6 7 9 19 50 100

NPL 0.113 -0.029 0.006 0.025 0.091 -0.106 0.222 0.889

Metrosert 0.12 -0.04 0.03 0.03 0.16 -0.08 0.28 1.02

BEV 0.07 -0.069 -0.028 -0.017 0.047 -0.121 0.222 0.901

CEM 0.1 -0.04 0.01 0.02 0.08 -0.07 0.25 0.9

MIRS/UM-FS/LTM 0.07 -0.07 -0.03 0 0.08 -0.1 0.250 0.9

DTI 0.08 -0.05 0.04 0 0.08 -0.07 0.27 0.94

NSAI 0.008 0.023 0.01 0.005 0.07 -0.085 0.235 0.933

MCCAA/MSA 0.056 -0.044 -0.001 0.14 0.15 -0.131 0.247 2.326

CETIME 0.08 -0.007 -0.08 0 0.08 -0.07 0.02 0.09

LATMB 0.06 -0.032 -0.029 0.004 0.072 -0.118 0.207 0.875

VMC/VMT 0.023 -0.069 -0.011 0.019 0.074 -0.124 0.248 0.949

MBM 0.04 -0.07 -0.03 -0.04 0.07 -0.12 0.26 0.99

Figure 4 to Figure 11 shows deviation from nominal length of the different gauge blocks with expanded uncertainty bars.


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Figure 4. Deviation from nominal length of the 0.5 mm gauge block. Expanded uncertainty bars.

Figure 5. Deviation from nominal length of the 1 mm gauge block. Expanded uncertainty bars.


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Participating laboratories were also reporting fo and fu values, and if possible, their corresponding uncertainties and those are listed in Table 5-7.

Table 5. fo and fu values (in µm) for the 0.5, 1, and 6 mm gauge blocks, as reported by the laboratories.

0.5 mm 1 mm 6 mm

fo u(fo) fu u(fu) fo u(fo) fu u(fu) fo u(fo) fu u(fu)

NPL 0.050 0.040 0.030 0.040 0.000 0.040 0.050 0.040 0.000 0.040 0.090 0.040

Metrosert - - - - - - - - 0.000 0.053 0.100 0.053

BEV - - - - - - - - 0.000 0.000 0.081 0.010

CEM 0.013 0.025 0.067 0.025 0.006 0.025 0.044 0.025 0.030 0.025 0.050 0.025

MIRS/ UM-FS/LTM

0.000 0.020 0.030 0.020 0.010 0.020 0.060 0.020 0.000 0.020 0.070 0.020

DTI 0.000 0.030 0.060 0.030 0.000 0.030 0.050 0.030 0.000 0.030 0.080 0.030

NSAI 0.025 0.057 0.558 0.057 0.050 0.058 0.083 0.058 0.000 0.064 0.050 0.064

MCCAA/ MSA

0.080 0.015 0.035 0.015 0.000 0.007 0.044 0.007 0.000 0.006 0.059 0.006

CETIME 0.010 0.080 0.010 0.080 0.040 0.080 0.020 0.080 0.020 0.080 0.000 0.080

LATMB 0.020 0.037 0.037 0.000 0.037 - 0.037 0.010 0.037 - 0.037

VMC/ VMT 0.036 0.048 0.057 0.048 0.097 0.048 0.051 0.048 0.106 0.051 0.093 0.051

MBM 0.070 0.039 0.610 0.039 0.020 0.039 0.190 0.039 0.030 0.043 0.030 0.043

Table 6. fo and fu values (in µm) for the 7, 9, and 19 mm gauge blocks, as reported by the laboratories.

7 mm 9 mm 19 mm

fo u(fo) fu u(fu) fo u(fo) fu u(fu) fo u(fo) fu u(fu)

NPL 0.000 0.040 0.070 0.040 0.000 0.040 0.110 0.040 0.000 0.040 0.200 0.040

Metrosert 0.000 0.053 0.040 0.053 0.000 0.053 0.090 0.053 0.000 0.053 0.160 0.053

BEV 0.000 0.000 0.091 0.010 0.000 0.000 0.103 0.010 0.000 0.000 0.169 0.010

CEM 0.029 0.025 0.046 0.025 0.070 0.025 0.096 0.025 0.102 0.026 0.160 0.026

MIRS/UM-FS/LTM

0.000 0.020 0.080 0.020 0.000 0.020 0.110 0.020 0.010 0.020 0.190 0.020

DTI 0.000 0.030 0.040 0.030 0.000 0.030 0.070 0.030 0.000 0.030 0.160 0.030

NSAI 0.000 0.065 0.013 0.065 0.000 0.067 0.016 0.067 0.000 0.079 0.170 0.079

MCCAA/ MSA

0.000 0.010 0.048 0.010 0.000 0.006 0.083 0.006 0.000 0.009 0.164 0.009

CETIME 0.030 0.080 0.040 0.080 - 0.080 0.060 0.080 0.050 0.080 0.010 0.080

LATMB 0.000 0.037 - 0.037 0.000 0.038 - 0.038 0.000 0.039 - 0.039

VMC/VMT 0.074 0.052 0.060 0.052 0.060 0.053 0.007 0.053 0.490 0.058 0.431 0.058

MBM 0.030 0.044 0.030 0.044 0.000 0.046 0.050 0.046 0.000 0.054 0.110 0.054


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Table 7. fo and fu values (in µm) for the 50 and 100 mm gauge blocks, as reported by the laboratories.

50 mm 100 mm

fo u(fo) fu u(fu) fo u(fo) fu u(fu)

NPL 0.080 0.040 0.040 0.040 0.007 0.040 0.073 0.040

Metrosert 0.060 0.053 0.030 0.053 0.050 0.053 0.090 0.053

BEV 0.053 0.010 0.037 0.010 0.023 0.010 0.068 0.010

CEM 0.050 0.031 0.028 0.031 0.032 0.043 0.076 0.043

MIRS/UM-FS/LTM

0.040 0.020 0.040 0.020 0.040 0.020 0.090 0.020

DTI 0.060 0.030 0.000 0.030 0.030 0.030 0.050 0.030

NSAI 0.043 0.114 0.022 0.114 0.017 0.172 0.063 0.172

MCCAA/ MSA

0.052 0.006 0.016 0.006 0.053 0.011 0.100 0.011

CETIME 0.060 0.080 0.000 0.080 - 0.080 0.050 0.080

LATMB 0.110 0.042 0.000 0.042 0.140 0.071 0.000 0.071

VMC/VMT 0.263 0.075 0.186 0.075 1.084 0.102 0.983 0.102

MBM 0.120 0.081 0.010 0.081 0.000 0.123 0.080 0.123

6.2 Measurement uncertainties

Table 8 shows the standard uncertainties as reported by the laboratories.

Table 8. Standard uncertainty (in m), as reported by the laboratories.

Gauge blocks nominal length / mm

Lab 0.5 1 6 7 9 19 50 100

NPL 0.016 0.016 0.017 0.017 0.017 0.018 0.025 0.042

Metrosert 0.027 0.027 0.027 0.027 0.027 0.028 0.035 0.053

BEV 0.021 0.021 0.021 0.021 0.021 0.022 0.025 0.04

CEM 0.025 0.025 0.025 0.025 0.025 0.026 0.031 0.043

MIRS/UM-FS/LTM 0.018 0.018 0.018 0.018 0.018 0.018 0.022 0.031

DTI 0.035 0.035 0.035 0.035 0.035 0.04 0.05 0.07

NSAI 0.058 0.058 0.064 0.065 0.067 0.079 0.114 0.172

MCCAA/MSA 0.05 0.05 0.052 0.052 0.052 0.055 0.063 0.075

CETIME 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08

LATMB 0.037 0.037 0.037 0.037 0.038 0.039 0.042 0.071

VMC/VMT 0.048 0.048 0.051 0.052 0.053 0.058 0.075 0.102

MBM 0.027 0.028 0.031 0.031 0.032 0.038 0.057 0.087


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Table 9 shows a summary of expanded uncertainties (k = 2) of those laboratories that reported approved CMC values in the BIPM KCDB.

Table 9. Expanded uncertainties as stated in BIPM KCDB and as stated in the supplementary comparison for those participating laboratories having CMC values in BIPM KCDB for End standards (mechanical comparison)

Lab CMC (BIPM KCDB) US22 Comment

NPL Q[22, 0.76L/mm]nm US22 = CMC

BEV Q[50, 0.4L/mm]nm US22 = CMC except for 100 mm gauge block, where US22 > CMC

Caused by large form deviation that caused a repositioning error (‘wobbling’)

CEM Q[50, 0.7L/mm]nm US22 = CMC

MIRS/UM-FS/LTM Q[35, 0.5L/mm]nm US22 = CMC

DTI Q[0.06, 0.001L/mm]m US22 > CMC The calibration was handled as calibration of class 1 (not class 0) gauge blocks causing a higher uncertainty

LATMB Q[90, 1.3L/mm]nm US22 < CMC

VMC/VMT Q[48, 0.54L/mm]nm US22 > CMC

6.3 Changes to results after Draft A.1

During the comparison there were some changes and corrections of results;

CETIME reported different values at different times, caused by a misprint when transferring data from one document to another. The values from CETIME used in the Draft B are the values stated as correct by CETIME.

Uncertainties from MIRS/UM-FS/LTM and DTI were expanded uncertainties in Draft A and those are corrected to standard uncertainties in Draft B.

BEV found that an error had occurred when the deviation from nominal length of the 100 mm gauge block was registered, probably caused by human error. BEV provided documentation for the correct value, which could be included in the next draft of the report.

All laboratories with En>1 were informed before data was published and had the possibility to check their results and make corrections.

6.4 Calculation of the SCRV

The Supplementary Comparison Reference Value (SCRV) is calculated as the weighted mean of the participant’s results. Check for consistency of the comparison results with the associated uncertainties was based on using the Birge ratio, and degree of equivalence were evaluated using En values.

An Excel sheet (kindly provided by Michael Matus, BEV) for calculation and evaluation was used and the analysis for each measurand is described below.


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The total number of participants submitting a result is I. Each laboratory reports a measured value, xi ,

and its associated standard uncertainty u(xi).

The normalised weight, wi , for the result xi is given by:

21

i

ixu

Cw (1)

where the normalising factor, C, is given by:

2

1

1

1

I

i ixu

C (2)

Then calculate the weighted mean, wx , which is given by:

I

i

iiw xwx1

(3)

The uncertainty of the weighted mean is calculated by:

C

xu

xuI

i i

w

2

1

1

1)( (4)

After deriving the weighted mean and its associated standard uncertainty, the deviation of each laboratory’s result from the weighted mean is determined simply as

wi xx . The uncertainty of this deviation is calculated as a combination of the uncertainties of the result, u(xi) , and the uncertainty of the weighted mean )( wxu . The uncertainty of the deviation from the weighted mean is given by equation (5), which includes a minus sign to take into account the correlation between the two uncertainties (it would be a plus sign if dealing with uncorrelated uncertainties, such as when comparing data from two separate laboratories).

22

wintiwi xuxuxxu (5)

For the determination of the supplementary comparison reference value SCRV, statistical consistency of the results contributing to the SCRV is required. A check for statistical consistency of the results with their associated uncertainties can be made by calculating the En value for each laboratory’s result, where En is defined as the ratio of the deviation from the weighted mean, divided by the expanded uncertainty of this deviation:

2int

22 wi

win

xuxu

xxE

(6)

The results are examined and any for which |En|> 1 is considered as inconsistent result and is not included.

Because inconsistent results are no longer correlated with the weighted mean, when calculating their

deviation from the weighted mean, and when calculating their En value, a positive sign is used in equation (5) and consequently in the denominator of equation (6). After reaching consistency, the calculated weighted mean is the SCRV.


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A statistically better way to check for consistency than the criterion |En|< 1 is to investigate by the so-called Birge ratio RB which compares the observed spread of the results with the spread expected from the individual reported uncertainties.

The application of least squares algorithms and the 2-test leads to the Birge ratio

w

wextB

xu

xuR , (7)

where )( wext xu is the external standard deviation

I

i

i

I

i

wii

wext

w

xxw

Ixu

1

1

2

1

1. (8)

Table 10. Key comparison reference value wx and associated standard uncertainty )( wxu .

Gauge block nominal length / mm

0.5 1 6 7 9 19 50 100

wx / m 0.073 -0.049 -0.007 0.006 0.078 -0.101 0.241 0.904

)( wxu / m 0.009 0.008 0.008 0.008 0.008 0.008 0.011 0.017

6.5 Calculation of Degrees of Equivalence

The Degree of Equivalence, DoE, for a laboratory result xi is calculated simply as wi xx . The

uncertainty of the DoE is calculated using either

22

wintiwi xuxuxxu for results which contributed to the weighted mean

or

2int

2

wiwi xuxuxxu for results which made no contribution.


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Table 11. Degrees of equivalence wi xx and associated expanded uncertainty

2int

22 wiwi xuxuxxU for 0.5 mm, 1 mm, 6 mm and 7 mm gauge blocks.

0.5 mm 1 mm 6 mm 7 mm

DoE/ µm

U(DoE)/µm

DoE/ µm

U(DoE)/µm

DoE/ µm

U(DoE)/µm

DoE/ µm

U(DoE)/µm

NPL 0.040 0.037 0.020 0.029 0.013 0.029 0.019 0.029

Metrosert 0.047 0.051 0.009 0.052 0.037 0.052 0.024 0.052

BEV -0.003 0.038 -0.020 0.039 -0.021 0.039 -0.023 0.039

CEM 0.027 0.047 0.009 0.047 0.017 0.047 0.014 0.047

MIRS/UM-FS/LTM

-0.003 0.031 -0.021 0.032 -0.023 0.032 -0.006 0.032

DTI 0.007 0.068 -0.001 0.068 0.047 0.068 -0.006 0.068

NSAI -0.065 0.115 0.072 0.115 0.017 0.127 -0.001 0.129

MCCAA/MSA -0.017 0.098 0.005 0.099 0.006 0.103 0.134 0.105

CETIME 0.007 0.159 0.042 0.159 -0.073 0.159 -0.006 0.159

LATMB -0.013 0.072 0.017 0.072 -0.022 0.072 -0.002 0.072

VMC/VMT -0.050 0.094 -0.020 0.095 -0.004 0.101 0.013 0.103

MBM -0.033 0.051 -0.021 0.054 -0.023 0.060 -0.046 0.060

Table 12. Degrees of equivalence wi xx and associated expanded uncertainty

2int

22 wiwi xuxuxxU for 9 mm, 19 mm, 50 mm and 100 mm gauge blocks.

9 mm 19 mm 50 mm 100 mm

DoE/ µm

U(DoE)/µm

DoE/ µm

U(DoE)/µm

DoE/ µm

U(DoE)/µm

DoE/ µm

U(DoE)/µm

NPL 0.013 0.029 -0.005 0.032 -0.019 0.046 -0.015 0.077

Metrosert 0.082 0.057 0.021 0.053 0.039 0.067 0.116 0.111

BEV -0.031 0.038 -0.020 0.041 -0.019 0.045 -0.003 0.072

CEM 0.002 0.047 0.031 0.049 0.009 0.058 -0.004 0.079

MIRS/UM-FS/LTM

0.002 0.032 0.001 0.032 0.009 0.039 -0.004 0.052

DTI 0.002 0.068 0.031 0.078 0.029 0.098 0.036 0.136

NSAI -0.008 0.133 0.016 0.157 -0.006 0.227 0.029 0.342

MCCAA/MSA 0.072 0.103 -0.030 0.109 0.006 0.124 1.422 0.154

CETIME 0.002 0.159 0.031 0.159 -0.221 0.162 -0.814 0.164

LATMB -0.006 0.074 -0.017 0.076 -0.034 0.081 -0.029 0.138

VMC/VMT -0.004 0.105 -0.023 0.115 0.007 0.148 0.045 0.201

MBM -0.008 0.062 -0.019 0.074 0.019 0.112 0.086 0.171


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Table 13. En values for all measurement results, where values marked in yellow represents questionable results (1<En≤1.5) and values marked in red represents unsatisfactory results (1.5<En).

0.5 mm 1 mm 6 mm 7 mm 9 mm 19 mm 50 mm 100 mm

NPL 1.08 0.70 0.45 0.65 0.45 0.17 0.41 0.20

Metrosert 0.93 0.18 0.72 0.46 1.45 0.39 0.58 1.04

BEV 0.07 0.51 0.54 0.60 0.80 0.50 0.42 0.05

CEM 0.59 0.19 0.36 0.29 0.04 0.62 0.15 0.06

MIRS/UM-FS/LTM

0.09 0.64 0.71 0.19 0.06 0.02 0.23 0.09

DTI 0.11 0.01 0.69 0.09 0.03 0.39 0.30 0.26

NSAI 0.56 0.63 0.13 0.01 0.06 0.10 0.03 0.08

MCCAA/MSA 0.17 0.05 0.06 1.27 0.70 0.28 0.05 9.24

CETIME 0.05 0.26 0.46 0.04 0.01 0.19 1.37 4.97

LATMB 0.18 0.24 0.30 0.03 0.08 0.23 0.42 0.21

VMC/VMT 0.53 0.21 0.04 0.12 0.04 0.20 0.05 0.22

MBM 0.64 0.39 0.38 0.77 0.13 0.26 0.17 0.50

6.6 Discussion of results

All gauge blocks had scratches and imperfections that are expected to have an influence on the results, affecting the uncertainty. This is in particular true for the result on the 100 mm gauge block from BEV, where problems with ‘wobbling’ caused a higher uncertainty than stated in the BIPM KCDB. Using gauge blocks that should represent ‘typical gauge blocks from customers’ also caused higher uncertainties than stated in BIPM KCDB for DTI. Because of the state of the gauge blocks, they were calibrated after the protocol used for class 1 gauge blocks by DTI, giving a higher uncertainty. However, when checking the En values using the ‘class 0 uncertainties’, they were still below one.

There was no indication that the gauge blocks were unstable during the comparison, but some gauge blocks had engravings that made it impossible for some of the laboratories to report all requested values (fo & fu). Furthermore, some results were excluded from the weighted mean because of En >1, as stated below;

- 0.5 mm gauge block: NPL

- 7 mm gauge block: MCCAA/MSA

- 9 mm gauge block: Metrosert

- 50 mm gauge block: CETIME

- 100 mm gauge block: MCCAA/MSA, CETIME and Metrosert


Pg. 19/19

7 References

[1] CCL/WG-MRA Guidance Document GD-1

[2] WG/MRA/GD-3 Guidance Document GD-3

[3] EURAMET cg-2, version 2, Calibration of Gauge Block Comparitor

[4] EUROMET Supplementary Comparison, EUROMET.L-S16

8 Acknowledgments

Acknowledgement to Harald Bosse (PTB), Michael Matus (BEV) and Jan Hald (DFM) for their constructive feedback and answering questions during the supplementary comparison.

A special acknowledgment to Andrew Lewis (NPL) for his guidance, discussions and templates that have been of great help and comfort during the supplementary comparison.

Documents

Report on Supplementary Comparison EURAMET.L · PDF filesupplementary comparison on gauge block measurements by mechanical comparison, numbered EURAMET.L ... e-mail: [email protected]