Asia-Pacific Metrology Programme

Transcription

1 Asia-Pacific Metrology Programme APMP Supplementary Comparison APMP.L-S3 Calibration of gauge blocks by mechanical comparison Final Report Co-ordinated by: -LIPI, Indonesia Assisted by:, Republic of Korea Report prepared by: A. Praba Drijarkara (-LIPI, Indonesia) Chu-Shik Kang (, Republic of Korea)

2 Table of Contents Abstract Introduction Preparatory and Concluding Workshops Organization Participants' details Comparison schedule Handling and transport Description of the Standards Steel gauge blocks: Tungsten carbide gauge blocks: Stability of standards Results Confirmation and amendment of results Reference value determination Degrees of equivalence Conclusion Tables of results... 9 Index of Tables Table 1. Participants in APMP.L-S Table 2. Planned and actual schedule of measurement... 5 Table 3. Mean values measured by, differences between each measurement and the average, and the uncertainties (in nm)... 6 Table 4. Central length deviation from nominal length (e) measured by participants (in nm) for steel and tungsten blocks, and their associated uncertainties at k = Table 5. Deviation of each laboratory from Reference Values, their associated uncertainties at k = 2, and the corresponding En value... 9 Table 6. En number between participants for Steel 1 mm Table 7. En number between participants for Steel 5 mm Table 8. En number between participants for Steel 10 mm Table 9. En number between participants for Steel 50 mm Table 10. En number between participants for Steel mm Table 11. En number between participants for Tungsten 1 mm Table 12. En number between participants for Tungsten 5 mm Table 13. En number between participants for Tungsten 10 mm Table 14. En number between participants for Tungsten 50 mm Table 15. En number between participants for Tungsten mm Page 2 of 15 APMP.L-S3-Final.v01.odt

3 Abstract This report summarizes the result of a comparison of length standards conducted between seven members of the Asia-Pacific Metrology Programme (APMP). Two sets of gauge blocks made of steel and tungsten carbide, each with nominal values 1 mm, 5 mm, 10 mm, 50 mm and mm were used as travelling standards. The comparison was co-ordinated by the Research Centre for Calibration, Instrumentation and Metrology Indonesian Institute of Sciences (-LIPI) and assisted by the Korea Research Institute of Standards and Science (), sponsored by the Physikalisch-Technische Bundesanstalt (PTB) through APMP's Developing Economies' Committee (DEC). The comparison was carried out from October 2006 to January Preparatory and concluding workshops were organized to assist the participants in preparing for the comparison and analyzing it. 1 Introduction The metrological equivalence of national measurement standards and of calibration certificates issued by national metrology institutes is established by a set of key comparisons chosen and organized by the Consultative Committees of the CIPM or by the regional metrology organizations in collaboration with the Consultative Committees. A key comparison on gauge block by interferometry has been carried out in APMP, known as APMP.L-K1, with NMIJ Japan as pilot. It was carried out from 2001 to 2002 and has been approved and published in the BIPM KCDB. Since not all APMP members participated in the APMP.L-K1, reason being that no interferometry facility was available, a need arose to carry out a comparison on gauge block by mechanical comparison. Hence, in the APMP Developing Economies' Committee meeting in 2003, it was decided to conduct a comparison on gauge block by mechanical comparison, with -LIPI Indonesia as coordinator. It should be noted that the initial purpose of the comparison was to provide NMIs of developing economies an exercise in conducting and participating in a comparison. Later on, however, it was suggested to have the comparison registered as a supplementary APMP comparison. Considering the different levels of capabilities among the Developing Economies' NMIs (DENs), this comparison was carried out in two loops. The first loop (dubbed the official loop ) was intended to be formally registered with KCDB or to be published in another media, so that it could be used as a means of supporting document for the laboratories' CMC claims. However, at the beginning of the comparison, it was not supported by APMP TCL then as the comparison was mainly for DENs. It was therefore started without formal registration. However, in view that the DENs are now more ready to take part in the CIPM MRA, the current Chair of APMP TCL advised to formalize the comparison. The request was put up by the APMP TCL Chair and it has been accepted for inclusion in the KCDB and given the identifier APMP.L-S3. The second loop (the nonofficial loop ), as it was originally intended, will remain as an exercise for the other laboratories. The procedures outlined in technical protocol of this comparison were principally intended to allow for a clear and unequivocal comparison of the measurement results and to complete the comparison in the time scale provided for. The procedures are based on the protocol for the APMP.L-K2 comparison, which was based on the inter-sim comparison on gauge blocks conducted from 1998 to 2001 (SIM.L-K1). A common way of evaluating and expressing the uncertainty of measurement is particularly important to demonstrate the degree of equivalence between the participating laboratories. By their declared intention to participate in this regional comparison, the laboratories accept the general instructions and the technical protocols written down in this document and commit themselves to follow the procedures strictly. Page 3 of 15 APMP.L-S3-Final.v01.odt

4 2 Preparatory and Concluding Workshops To give technical support in preparing and carrying out the comparison, PTB Germany has sponsored a preparatory workshop which was held in Indonesia, hosted by -LIPI and attended by some of the interested NMIs in December PTB also provided funding for experts from Korea to act as coach in the comparison, starting from giving lectures in the preparatory workshop, assisting in the preparation of technical protocol and artefacts, providing reference values, and helping to evaluate the results. A concluding workshop was organized after the second loop was finished. Similar to the opening workshop, this one was also hosted by -LIPI, sponsored by PTB and assisted by. The purpose of the concluding workshop was to discuss the result of measurement and any discrepancies that might have been found, and how to prepare the final report. The Draft A report was presented and accepted at this workshop. During this workshop, some participants performed repeat measurement on the same travelling standards using their own reference gauge blocks, i.e., the same standard that they had used to perform the measurement for the comparison. The purpose of this repeat measurement was to confirm measurement values that might be outliers and to investigate the possible cause, but not to change the reported values. 3 Organization APMP members and associate members, especially NMI of developing economies, were invited to participate in the comparison. The service being tested in the comparison is the measurement of central lengths of gauge blocks by mechanical comparison, both for steel gauge blocks and tungsten carbide blocks covering the range from 1 mm to mm. Korea provided the reference value by interferometric measurement. 3.1 Participants' details The following is the list of participants at the end of the comparison. Mr. A. Praba Drijarkara -LIPI (Coordinator) Dr. Chu-Shik Kang Table 1. Participants in APMP.L-S3 NMI Economy Contact Mr. Anusorn Tonmueanwai Dr. Ahmad Makinudin Dahlan NML- Mr. Bui Quoc Thu Dr. K P Chaudary NPL Mr. Masood Ahmed Indonesia Rep. of Korea Thailand Malaysia Vietnam India Pakistan probo@kim.lipi.go.id, probodj@gmail.com Fax: Telephone: ext 3070 cskang@kriss.re.kr Fax: Telephone: anusorn@nimt.or.th Fax: Telephone: ahmadmd@sirim.my Fax: Telephone: bqthu_lengthvmi@fpt.vn, vmi@hn.vnn.vn Fax: Telephone: kpc@mail.nplindia.ernet.in Fax : Telephone: masaudmlk@yahoo.com Fax Telephone Page 4 of 15 APMP.L-S3-Final.v01.odt

5 3.2 Comparison schedule The comparison was originally planned to start in October 2006 and finish by November However, due to some delays, the last measurement was only finished in December The delays were mainly due to lengthy customs clearance in some countries and problems with environmental conditioning systems in some laboratories (namely -LIPI and one of the participant in the second loop). Table 2. Planned and actual schedule of measurement Laboratory Country Planned Actual R. Korea October 2006 October LIPI Indonesia November 2006 November 2006 Thailand December 2006 December 2006 NML- Malaysia January 2007 February 2007 Vietnam February 2007 March 2007 NPL India March 2007 June 2007 Pakistan April 2007 September LIPI Indonesia May 2007 November 2008 R. Korea June 2007 January 2009 Second loop participants July-October 2007 March-June LIPI Indonesia November 2007 September 2009 R. Korea December 2007 December Handling and transport The standards showed some damage in the form of scratches, but not so much as to affect either interferometric or mechanical measurement. The scratches were more prominent on the mm steel block in the direction similar to the movement of gauges during measurement, suggesting that the source of scratches was from gauge support on the comparator. 4 Description of the Standards The standards consisted of 5 gauge blocks of steel and 5 gauge blocks of tungsten carbide. The gauge blocks are of rectangular cross section, according to the International Standard ISO The thermal expansion coefficient and its standard uncertainty (k=1) supplied by the manufacturer were informed to participants for use. 4.1 Steel gauge blocks: Identification Nominal length (mm) Expansion coeff. (10-6 K -1 ) Manufacturer K ± 0.5 KOBA K ± 0.5 KOBA K ± 0.5 KOBA K ± 0.5 KOBA K 11.9 ± 0.5 KOBA 4.2 Tungsten carbide gauge blocks: Identification Nominal length (mm) Expansion coeff. (10-6 K -1 ) Manufacturer K ± 0.3 KOBA K ± 0.3 KOBA K ± 0.3 KOBA K ± 0.3 KOBA K 4.5 ± 0.3 KOBA Page 5 of 15 APMP.L-S3-Final.v01.odt

6 Some physical properties of materials taken from the manufacturer s information are listed in the following table. 1 Material Expansion coeff. (10-6 K -1 ) Poisson s ratio Young s modulus Steel 10.9 ± ± GPa ± 2 % Tungsten carbide 4.5 ± ± GPa ± 5 % diamond 0.8 ± ± GPa ± 2 % 5 Stability of standards As the reference value provider, measured the standards by interferometric method three times: at the beginning of the first loop, between the two loops, and at the end of the second loop. The result of these measurements, besides being used to determine the reference values, can also be used as a measure of stability of the standards. Table 3 shows the mean of the three measurements by, and the difference between each measurement and the average value. The uncertainties (at k = 2) are the uncertainty values for interferometric measurement performed by, which is Q[28, 0.19L] nm (L in mm). Table 3. Mean values measured by, differences between each measurement and the average, and the uncertainties (in nm) Mean Diff-1 Diff-2 Diff-3 Unc. (k=2) Steel 1 mm Steel 5 mm Steel 10 mm Steel 50 mm Steel mm Tungsten 1 mm Tungsten 5 mm Tungsten 10 mm Tungsten 50 mm Tungsten mm Steel-1 Steel-5 8,00 Steel-10 6,00 Steel-50 4,00 Steel- Tungsten-1 2,00 Tungsten-5 Tungsten-10-2,00 Tungsten-50 Tungsten- -4,00-6,00-8, Figure 1. Difference between each measurement by relative to the average values. From these values, it can be seen that there is no apparent systematic drift of values. All differences are negligible with respect to their uncertainties. Therefore, it is safe to consider the reference values can be calculated from simple means of these values. 1 The values given in this table for diamond are just typical ones. If the data could be obtained from the manufacturer of the diamond tip, then those values shall be used in the calculation. Page 6 of 15 APMP.L-S3-Final.v01.odt

7 6 Results 6.1 Confirmation and amendment of results After all participants had sent their results, interim reports were sent individually to each laboratory to confirm their reported values and seek clarification for unclear values. After all participants confirmed their result, interim calculations were made to detect any possible outliers. and NSCL were informed that their values for Tungsten 50 mm were outlier, without specifying the magnitude nor the direction of the deviations, and were advised to re-check their values for possible miscalculation. responded and requested to change their report (from 320 nm to 150 nm). responded that their calculations were correct and did not ask to change their report. After this, Draft A report was circulated and was accepted. No more changes were made to the results. Table 4 shows the measurement results from the laboratories. Values from and -LIPI include those taken during the second (non-official) loop. 6.2 Reference value determination As mentioned previously, the reference values for this comparison are taken from the simple average of the three measurements carried out interferometrically by. However, the uncertainty values are taken from the typical 's uncertainty values for gauge block measurement by mechanical comparison. The reason for this is to give more reasonable degrees of equivalence when comparing 's values to the other participants'. A similar approach had been used in another comparison of calibration of gauge blocks by mechanical comparison, where the reference value was determined through interferometric measurement by PTB (Metrologia, 1997, 34, ). The uncertainty of measurement for the reference values are given by the following equation: where l is the nominal length of the gauge blocks. u X ref = 26nm l Degrees of equivalence Table 5 shows the differences between each laboratory and the reference values, standard uncertainties of these differences, and the E n number defined by x E n = A x ref 2 u 2 x A u 2 x ref where x A is the measurement value from Lab A, x ref is the reference value, and u(x A ) and u(x ref ) are their associated standard uncertainties. -LIPI's value is taken from the average of three measurements (first loop, between the first and second loop, and at the end of second loop). Tables 6 to 15 show the E n number for each pair of participants. E n values between Lab A and Lab B are calculated according to the following formula: x E n = A x B 2 u 2 x A u 2 x B where x A and x B are measurement values from Lab A and Lab B, respectively, and u(x A ) and u(x B ) are their associated standard uncertainties. Page 7 of 15 APMP.L-S3-Final.v01.odt

8 7 Conclusion The majority of the result from the participating laboratories are consistent with the Reference Value, except for the result of 50 mm Tungsten by. As mentioned earlier in this report, during the concluding workshop a repeat measurement was carried out by participant from. The result of the repeat measurement was consistent with their original measurement, and the deviation was attributed to the large deviation in the calibration certificate of the reference block. Either the calibration certificate reported the wrong result for that particular block, or that particular block had changed since it was calibrated. The damages (scratches) on the travelling standard did not seem to affect the result, as attested by the consistency of the three interferometric measurement by. Page 8 of 15 APMP.L-S3-Final.v01.odt

9 8 Tables of results Table 4. Central length deviation from nominal length (e) measured by participants (in nm) for steel and tungsten blocks, and their associated uncertainties at k = e unc. e unc. e unc. e unc. e unc. e unc. Steel 1 mm Steel 5 mm Steel 10 mm Steel 50 mm Steel mm Tungsten 1 mm Tungsten 5 mm Tungsten 10 mm Tungsten 50 mm Tungsten mm e unc. e unc. e unc. e unc. e unc. Steel 1 mm Steel 5 mm Steel 10 mm Steel 50 mm Steel mm Tungsten 1 mm Tungsten 5 mm Tungsten 10 mm Tungsten 50 mm Tungsten mm Table 5. Deviation of each laboratory from Reference Values, their associated uncertainties at k = 2, and the corresponding En value Diff U E n Diff U E n Diff U E n Diff U E n Diff U E n Diff U E n Steel 1 mm , , , , , ,02 Steel 5 mm , , , , , ,87 Steel 10 mm , , , , ,36 Steel 50 mm , , , , , ,40 Steel mm , , , , , ,62 Tungsten 1 mm , , , , , ,46 Tungsten 5 mm , , , , , ,13 Tungsten 10 mm , , , , Tungsten 50 mm , , , , , ,06 Tungsten mm , , , , , ,58 The following graphs show the differences between the participants' results and the reference values with error bars representing uncertainty values at k = 2. The number underneath each laboratory's name indicates the En number. Page 9 of 15 APMP.L-S3-Final.v01.odt

10 ,39-0,12-0,25 0,35-0,11 0,02 Steel 1 mm Figure 2. Difference between laboratories and reference value for Steel 1 mm. The number under each ,32 0,15-0,20 0,02 0,14 0,87 Steel 5 mm Figure 3. Difference between laboratories and reference value for Steel 5 mm. The number under each ,39-0,12-0,45-0,11-0,36 Steel 10 mm Figure 4. Difference between laboratories and reference value for Steel 10 mm. The number under each Page 10 of 15 APMP.L-S3-Final.v01.odt

11 ,20-0,15-0,18 0,38 0,39-0,40 Steel 50 mm Figure 5. Difference between laboratories and reference value for Steel 50 mm. The number under each ,01-0,02-0,02 0,30 0,59 0,62 Steel mm Figure 6. Difference between laboratories and reference value for Steel mm. The number under each ,12-0,30 0,39 0,06 0,60-0,46 Tungsten 1 mm Figure 7. Difference between laboratories and reference value for Tungsten 1 mm. The number under each Page 11 of 15 APMP.L-S3-Final.v01.odt

12 ,21-0,49 0,10-0,20 0,17-0,13 Tungsten 5 mm Figure 8. Difference between laboratories and reference value for Tungsten 5 mm. The number under each ,15-0,19 0,28 0,49 Tungsten 10 mm Figure 9. Difference between laboratories and reference value for Tungsten 10 mm. The number under each ,05 0,10 0,20-0,18 0,23-1,06 Tungsten 50 mm Figure 10. Difference between laboratories and reference value for Tungsten 50 mm. The number under each Page 12 of 15 APMP.L-S3-Final.v01.odt

13 ,17 0,02 0,18-0,48 0,41-0,58 Tungsten mm Figure 11. Difference between laboratories and reference value for Tungsten mm. The number under each Table 6. En number between participants for Steel 1 mm 0,47 0,57 0,05 0,46 0,31-0,47 0,13-0,43-0,10-0,57-0,13-0,53-0,12-0,20-0,05 0,43 0,53 0,41 0,27-0,46 0,12-0,41-0,10-0,31 0,10 0,20-0,27 0,10 Table 7. En number between participants for Steel 5 mm 0,18 0,46 0,26 0,17-0,46-0,18 0,33 0,10-0,71-0,46-0,33-0,18-0,30-0,98-0,26-0,10 0,18-0,10-0,72-0,17 0,30 0,10-0,67 0,46 0,71 0,98 0,72 0,67 Table 8. En number between participants for Steel 10 mm 0,46 0,73 0,33 0,43 0,60-0,46 0,29-0,10 0,25-0,73-0,29-0,36-0,26 0,04-0,33 0,10 0,36 0,09 0,32-0,43 0,26-0,09 0,24-0,60-0,25-0,04-0,32-0,24 Table 9. En number between participants for Steel 50 mm 0,30 0,33-0,17-0,21 0,49-0,30 0,01-0,46-0,46 0,26-0,33-0,01-0,49-0,49 0,27 0,17 0,46 0,49-0,06 0,61 0,21 0,46 0,49 0,06 0,61-0,49-0,26-0,27-0,61-0,61 Page 13 of 15 APMP.L-S3-Final.v01.odt

14 Table 10. En number between participants for Steel mm 0,01-0,28-0,55-0,59-0,01-0,29-0,56-0,60-0,29-0,56-0,60 0,28 0,29 0,29-0,28-0,34 0,55 0,56 0,56 0,28-0,09 0,59 0,60 0,60 0,34 0,09 Table 11. En number between participants for Tungsten 1 mm 0,12-0,43-0,14-0,61 0,28-0,12-0,64-0,25-0,81 0,20 0,43 0,64 0,20-0,24 0,73 0,14 0,25-0,20-0,38 0,38 0,61 0,81 0,24 0,38 0,88-0,28-0,20-0,73-0,38-0,88 Table 12. En number between participants for Tungsten 5 mm 0,22-0,27 0,03-0,32-0,06-0,22-0,53-0,16-0,53-0,28 0,27 0,53 0,25-0,08 0,20-0,03 0,16-0,25-0,30-0,08 0,32 0,53 0,08 0,30 0,26 0,06 0,28-0,20 0,08-0,26 Table 13. En number between participants for Tungsten 10 mm 0,28-0,09 0,10-0,31 0,10-0,28-0,38-0,14-0,55-0,15 0,09 0,38 0,18-0,25 0,19-0,10 0,14-0,18-0,36 0,31 0,55 0,25 0,36 0,37-0,10 0,15-0,19-0,37 Table 14. En number between participants for Tungsten 50 mm -0,12-0,21 0,12-0,24 0,92 0,12 0,01 0,19-0,04 0,69 0,21-0,01 0,32-0,09 1,17-0,12-0,19-0,32-0,33 0,74 0,24 0,04 0,09 0,33 1,05-0,92-0,69-1,17-0,74-1,05 Page 14 of 15 APMP.L-S3-Final.v01.odt

15 Table 15. En number between participants for Tungsten mm -0,09-0,33 0,29-0,51 0,39 0,09-0,05 0,24-0,18 0,30 0,33 0,05 0,62-0,28 0,71-0,29-0,24-0,62-0,74 0,11 0,51 0,18 0,28 0,74 0,82-0,39-0,30-0,71-0,11-0,82 [APD] [APMP.L-S3-Final.v01.odt] [ :53] Page 15 of 15 APMP.L-S3-Final.v01.odt