BRML INM. National Metrology Institute. COOMET Comparison COOMET.L-S20 676/MD/15. Calibration of gauge blocks by comparison. Technical protocol

Transcription

1 BRML INM National Metrology Institute COOMET Comparison COOMET.L-S20 676/MD/5 Calibration of gauge blocks by comparison Technical protocol

2 Contents. INTRODUCTION ORGANISATION Participants Time schedule Transportation Unpacking, Handling, Packing Financial aspects, insurance DESCRIPTION OF THE STANDARDS MEASUREMENT INSTRUCTIONS MEASUREMENT UNCERTAINTY REPORTING

3 . Introduction. The metrological equivalence of national measurement standards will be determined by a set of key and supplementary comparisons chosen and organized by the Consultative Committees of the CIPM working closely with the Regional Metrology Organizations (RMOs)..2 The comparison is organised within the Twinning MD/3/ENP/TR/4 Strengthening of the standards and metrology sector according to the best practice in the EU Member States..3 BRML INM RO is acting as the pilot laboratory and in this function is responsible for providing the travelling standard, receives the participant s measurement results, the evaluation of the measurement results and the final report. INM MD fulfils the role of co-pilot laboratory and in this function is responsible for the registration the comparison and for the approving the technical protocol and the final report..4 The comparison will be conducted in accordance with the rules and procedures for comparisons COOMET and BIPM Guidelines for Planning, Organising, Conducting and Reporting Key, Supplementary and Pilot Comparisons..5 A goal of the this comparisons is to demonstrate the equivalence of routine calibration services offered by NMIs to clients, as listed in Appendix C of the Mutual Recognition Agreement (MRA) [BIPM, 999]. To this end, participants in this comparison agree to use the same apparatus and methods as routinely applied to client artefacts. 2. Organisation The technical protocol has been drafted by the pilot laboratory with assistance from INM Moldavia. 2.. Participants DE Peter Franke LT Lilija Chaleckienė Pilot: RO Alexandru Duta Co-pilot: MD Alexandru Mîrza PTB - Physikalisch-Technische Bundesanstalt Bundesallee 00 D-386 Braunschweig Deutschland (Germany) VMC - Vilniaus Metrologijos Centras Dariaus ir Gireno g. 23, LT-0289, Vilnius, Lietuva INM National Institute of Metrology, Sos. Vitan-Bârzesti RO Bucharest 4 ROMANIA INM - National Institute of Metrology 28 E. Coca str., MD 2064, CHISINAU Tel.: +49 (0) Fax. peter.franke@ptb.de Tel l.chaleckiene@vmc.lt Tel Fax Alexandru.duta@inm.ro Tel Fax lungimi@metrologie.md 3

4 2.2. Time schedule Each laboratory has approximately 4 weeks for calibration, including transportation. Laboratory Country Date BRML - INM RO June 206 PTB DE July 206 INM MD August 206 VMC LT September 206 BRML - INM RO October Transportation Transportation is each laboratory s own responsibility and cost. The standards are packed in a box ready to be shipped. The gauge blocks are stored in a wooden box with serial (dimensions 260 mm x 20 mm x 50 mm). You are kindly asked to inform the pilot laboratory by fax immediately after receiving the gauge blocks using the fax form in the annex. Immediately after completing the measurements, the pack has to be sent or taken to BRML - INM. It is advisable to prepare and organize this transportation beforehand. Please inform the coordinator fax or about date of shipment, transportation company and flight details Unpacking, Handling, Packing The package contains the following items: one wooden box containing 9 gauge blocks The technical protocol will be ed to each participant at the start of the project and will not be sent separately with the gauge blocks. After receiving the package, the standards have to be inspected carefully for any damage, scratches or rust. The gauges should be de-greased. The gauge blocks must be handled with care! Any damage has to be communicated to the pilot laboratory. The measurement surfaces should never be re-lapped or re-polished! After the measurements, the gauge blocks have to be cleaned and the steel gauge should be greased. All gauges should be wrapped in anti-rust-paper. Ensure that the content of the package is complete before shipment. Use always the original package unless is becomes too damaged. 4

5 2.5. Financial aspects, insurance Each participating laboratory covers the costs for the measurements, transportation and eventual customs formalities 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 standards during transportation. 3. Description of the Standards The package contains 9 gauge blocks made of steel. The gauge blocks are Calibration grade K and of rectangular cross section, according to the international standard ISO Identification No. Nominal length Expansion coefficient Manufacturer (mm) (0-6 K - ) unknown KOBA unknown KOBA unknown KOBA unknown KOBA unknown KOBA unknown KOBA unknown KOBA unknown KOBA unknown KOBA 4. Measurement instructions Before and after the calibration, the gauge blocks have to be inspected on damage on the measurement surfaces. Any scratches, rusty spots or other damages has to be documented by a drawing or sketching in the appropriate form in the annex 2. The wringing properties of all measuring faces have to be tested and documented before and after the calibration. The gauges should be left in the laboratory environment for an adequate period to allow temperature stabilisation. The gauge block temperature and/or surface plate temperature should be recorded at the beginning and end of the calibration. The gauge blocks should be measured by mechanical comparison with the laboratory s reference gauge blocks, using the normal calibration procedure. The PTB will calibrate the deviation of the central length from the nominal length by interferometry method and the deviations f o and f u by mechanical comparison method. The following are the measurands for each gauge block: Deviation of the central length l c (at P in figure below) from the nominal length l n Where possible, deviation from nominal length, measured at points P2 to P5. These values will be used by each participant to calculate f o and f u, for each gauge, according to ISO The results should be recorded in Annex. 5

6 The figure shows the measuring points on the gauge block P5 P4 P P2 P3 The gauges should be positioned as follows: -, 5 and 0 mm gauge blocks the measuring face with the nominal size markings should face upwards with the nominal size mark on the left side of the gauge facing the operator: - 5, 20, 25, 50, 75 and 00 mm gauge blocks the side of the gauge with the nominal size marking should be standing vertically, facing the operator with the numerals running up the gauge side: 5. Measurement uncertainty The uncertainty of measurement shall be estimated and reported as would be normal for mechanical comparison according to the ISO Guide for the Expression of Uncertainty in Measurement. 6. Reporting The quality of the measurement surfaces of the gauge blocks, the measurement results, instrument descriptions and a detailed evaluation of the uncertainty of measurement have to be reported using the forms enclosed in the annex. Handwritten notes are sufficient but electronic submission is preferred. The measurement report forms in the annex of this document are sent by (Word document) to all participating laboratories. It would be appreciated if the report forms (in particular the results sheet) could be completed by computer and sent back electronically to the coordinator. In any case, the signed report must also be sent in paper form by mail. In case of any differences, the paper forms are considered to be the valid version. 6

7 The reports shall be sent to the pilot laboratory within four weeks after completing the measurements. No information about differences of the reported results with respect to other laboratories will be discussed before the completion of the comparison, unless large deviations of particular laboratories with respect to the preliminary reference results obtained by the pilot laboratory have been observed. In the latter case the laboratory in question will be contacted. Within 2 months after completion of the circulation, the pilot and co-pilot laboratories will prepare a first draft report and send it to the participants for comment. Subsequently, the procedure outlined in the BIPM Guidelines will be followed. 7

8 Annex : Measurement results for steel gauges P5 P2 P P4 P3 Nominal length Deviation of the central length from the nominal lenght Uncertainty (k=) u(l c-l n) Deviation from the central f o Deviation from the central f u Uncertainty (k=) u(fo/ fu) Ident.- No. [mm] l c - l n [nm] [nm] [nm] [nm] [nm] Please prepare a detailed uncertainty budget for the calibration of the 00 mm gauge block using the form in Annex 3.

9 Annex 2: Inspection of the measurement surfaces, steel gauge blocks The wringing properties of all measuring faces have to be tested and documented before and after the calibration. mm 5 mm 0 mm marked unmarked marked unmarked right left 5 mm 20 mm 25 mm right left right left right left 50 mm 75 mm 00 mm right left right left right left 2

10 Annex 3: Uncertainty of Measurement The statement of uncertainty in the result form in Annexes should be consistent with the ISO-Guide for the expression of uncertainty in measurement. Please indicate below if possible, the different input quantities which have been used to estimate the reported uncertainty. Please extend and edit the tables as necessary. This detailed information is provided for the 00 mm block. Uncertainty evaluation for 00 mm steel gauge block Input Quantity Description Assumed distribution Type A or Type B Standard uncertainty value (k=) Combined standard uncertainty (u c)=

11 Annex 4: Description of the measurement instrument Make and type of comparator... Resolution of Comparator & electronics Type and grade of reference gauge block used Range of gauge block temperature during measurement...

12 Telefax Telefax Telefax Telefax Telefax To: INM National Institute of Metrology, Sos. Vitan-Bârzesti RO Bucharest 4 ROMANIA From: We confirm having received the standards of the COOMET.L-S.. supplementary comparison on. After visual inspection no damage has been noticed (the package) the following damage(s) must be reported: Date: Signature: