EUROPEAN cooperation for ACCREDITATION Dr. Carlo Ferrero Istituto di Metrologia G. Colonnetti

Main Activities in the EA Mechanical Measurement: the Force and Torque Dissemination in Italy Carlo Ferrero EA Chairman of Mechanical Measurements Commission, IMGC-CNR Force and Torque Responsible Istituto di Metrologia G. Colonnetti

Overview of developments since 1974 WEMC Western European Metrology Club 1974-1989 (NMI Directors) WG Calibration WEMC Working Group Calibration 1975-1976 WECC Western European 1975-1994 Calibration Cooperation EUROMET WELAC Western European WELMEC 1988 Laboratory Accreditation 1989-1994 1990 National Standards European Collaboration Cooperation Legal Metrology Western European EAC in Measurement Standards Legal Metrology 1991-1994 Cooperation EAL European 1994-1997 European Accreditation Accreditation of Certification of Laboratories EA European cooperation for 1997 Accreditation Accreditation

Calibration Laboratories Accredited in Each European Country Istituto di Metrologia G. Colonnetti

Regional Accreditation Bodies

Regional Accreditation Bodies APLAC = Asia Pacific Laboratory Accreditation Cooperation EA = European cooperation for Accreditation ILAC = International Laboratory Accreditation Cooperation NACC = North American calibration Cooperation PAC = Pacific Accreditation Cooperation

Hardness, Torque, Mass, Force EA Laboratory Committee Activities Working Group: MECHANICAL MEASUREMENTS  Hardness, Torque, Mass, Force Convener: CARLO FERRERO (SIT-IMGC) Istituto di Metrologia G. Colonnetti

EA-INTERCOMPARISON ON HARDNESS

Background The EA-Guidance EA-10/16 was considered in the Final Measurement Instructions so that the comparison EA-H1 also serves to prove the applicability of this EA-Guidance. The comparison contained two sets of measurements: the first set with the indenter of the participating laboratory the second set with a common indenter delivered by the organizer of the comparison. The idea for this design of the comparison was to analyze the most important sources of uncertainty occurring presently in Rockwell hardness measurements.

Results of participating laboratories The results of the measurements are displayed in tabular form and in graphical representation. The En ratio is expressed by the following equation: where Hl, Hr are the hardness measuring values of the participating laboratory and the reference laboratory, respectively, and Ul, Ur are the uncertainties associated with the participating laboratory and the reference laboratory, respectively

Results of the measurements on hardness reference blocks, expressed as deviation from reference value, with nominal hardness of 25 HRC using the institute‘s indenter Results of the measurements on hardness reference blocks, expressed as deviation from reference value, with nominal hardness of 25 HRC using the common indenter Istituto di Metrologia G. Colonnetti

Results of the measurements on hardness reference blocks, expressed as deviation from reference value, with nominal hardness of 45 HRC using the institute‘s indenter Results of the measurements on hardness reference blocks, expressed as deviation from reference value, with nominal hardness of 45 HRC using the common indenter

The mean absolute deviations are clearly smaller for the common indenter than for the institute’s indenter. The mean absolute deviations range for the common indenter between 0,31 and 0,37 HRC and for the institute’s indenter between 0,37 and 0,67 HRC.

This reveals the strong influence of the geometrical deviations of the used indenters on the uncertainty of the achieved measurement results. Moreover, the mean absolute deviations for the institute’s indenters represent the presently achievable degree of agreement of measurements between the participants.

level of repeatability the level of repeatability of the participants standard hardness calibrating machines is s5 < 0,10 HRC.

Conclusions Interlaboratory comparison H1 was the first comparison in the field of hardness measurement within EA. It was succesfully carried out for the most important hardness scale HRC by 11 laboratories from 7 European countries. The results of EA H1 in a rather representative way reflect the present state of accuracy level of hardness calibration laboratories in the framework of EA.  

The mean absolute deviations range for the common indenter between 0,31 and 0,37 HRC and for the institute’s indenter between 0,37 and 0,67 HRC. This difference between both indenter types reveals the strong influence of the geometrical deviations of the used indenters on the uncertainty of the achieved measurement results

NEW EA PROPOSALS ON HARDNESS ACTIVITIES September 2004 . EA/ LC Meeting in Bukarest Istituto di Metrologia G. Colonnetti

NEW EA PROPOSALS ON HARDNESS ACTIVITIES The activities in the field of hardness are the following: 1) EA-Guideline EA-10/16 . New examples on the Uncertainty of Brinell and Vickers measurements. Some comments were received until last year. Under consideration of these comments and the drafts for the clause on uncertainty of measurement in preparation for the revised ISO standards on Rockwell, Vickers and Brinell (ISO 6506, ISO 6507 and ISO 6508) the new draft was made by EA-WG until July 2004 and was presented in September at the EA/LC Istituto di Metrologia G. Colonnetti

PTB, MPA Hannover have elaborated a programme for ILC/H2. 2) Interlaboratory comparison on Hardness ILC/H2 on Hardness Testing Machines PTB, MPA Hannover have elaborated a programme for ILC/H2. The aim should be to check the uniformity and correctness of calibration procedures for hardness testing machines SIT and IMGC are supporting this new ILC. ILC-H2 could be realised at the National level with the participation of invited laboratories of the border countries.  Istituto di Metrologia G. Colonnetti

EA-Intercomparison on Torque (ILC-T2)

ILC-T2 The EA Expert Group on „Mechanical Measurements“, decided: to carry out a comparison of torque measurements in the range of 1 N·m to 2000 N·m. The EA-Guidance EA-10/14 was considered in the Final Measurement Instructions so that the comparison T2 also serves: to prove the applicability of this EA-Guidance. The comparison was decided as a star type to estimate in a better way: The long-term stability of the transfer standards.

Schedule The EA interlaboratory comparison T2 was organised by the (German Calibration Service, DKD) in co-operation with the torque laboratory of PTB.

The reference values were taken from the PTB’s torque standard machines 1-kN·m-Dm-NME (1 kN·m TSM, measuring range 1 N·m to 1000 N·m, Wbmc = 2·10-5 (k = 2)) and the 20-kN·m-Dm-NME (20 kN·m TSM, measuring range 100 N·m to 20000 N·m, Wbmc = 2·10-5 (k = 2)) The following transfer standards were used:

The result of ILC is correlated to the definition of the factor En. The difference of the measurement with the same transfer equipment D rel. dev. is the mean value from the measurement in 3 or 4 positions (3 x 120° or 4 x 90° rotated in the axis of the transducer).

The following tables give the information about the ILC factor for some participants.

Germany 2

Germany 2

AAAAAA An example of Certificate with….some problems

Some General remarks…… 1.      Value of the sensitivity S were given only with 2 or 3 figures 2.      Mistake in the measurement by 4 N·m cw 0°/1down (TN 10 N·m) 3.      Resolution is given in % and not in N·m 4.      Most parameters are not calculated in accordance with EA-10/14 incl. mean value 5.      acw torque is given positive sign (special TN 10 N·m) 6.      The lab has problems with the tare at zero (TT1 100 N·m, TT1 500 N·m) 7.      Interpolation deviation without sign (only positive) 8.      Missing information about classification …….to be evaluated by the NAB

ITALY 2

ITALY 2 Certificates and results in accordance to EA-10/14, not in English The bmc in the range smaller than 2 N·m is not described in the certificate The result of calculation of the uncertainty is not correlated to the uncertainty of the TCM

Conclusion Interlaboratory comparison T2 was the second comparison in the field of torque measurement within EA. It was successfully carried out for the most important torque scale by 16 laboratories from 11 European countries and 3 laboratories from 3 countries outside of Europe The results of EA T2 in a rather representative way reflect the present state of accuracy level of torque calibration laboratories in the framework of EA. The stability of the reference value measured by the laboratory DE1 during the time of the comparison could be proven and was satisfying