1、AECMA STANDARD NORME AECMA AECMA NORM Edition approved for publication prEN 2004-7 Edition P 1 February 1996 C5 Chairman Comments should be sent within six months after the date of publication to PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES (AECMA) Gulledelle 94 - 8-1 200 BRUXELLES
2、- Tel. (32) 2 775 81 10 - Fax. (32) 2 775 81 11 ICs : Descriptors ENGLISH VERSION Aerospace series Test methods for aluminium and aluminium alloy products Part 7 : Reference blocks for the calibration of measuring equipment used in the determination of electrical conductivity of wrought aluminium an
3、d aluminium alloys Srie arospatiale Mthodes dessais applicables aux produits en aluminium et alliages daluminium Partie 7 : Blocs de rfrence pour ltalonnage pour la dtermination de la conductivit lectrique daluminium et dalliages daluminium corroys Luft- und Raumfahrt Prfverfahren fr Erzeugnisse aus
4、 Aluminium und Aluminiumlegierungen Teil 7 : Referenzblcke zur Eichung von Megerten zur Bestimmung der elektrischen Leitfhigkeit von gekneteten Aluminium und Aluminium-Legierungen This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aer
5、ospace Industries). it is published on green paper for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Technical Committee following comment by the Member countries. Subsequent to the publication of this Prestandard, the technical content shall not be cha
6、nged to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre NPS) and formal agreement of the Officiai Services of the Member countries it will be submitted as a dra
7、ft European Standard to CEN (European Committee for Standardization) for formal vote. 1996-02-29 AECMA Gulledelle 94 B-1200 BRUXELLES Mr Odorico AECMA PREN*2804-7 96 W 1012311 0010685 463 W Page 2 EN 2004-7 : 1996 Contents list 1 Scope . 2 Normative references 3 Definitions . 4 Production and calibr
8、ation of master reference standards . 5 Production and calibration of secondary reference blocks . 6 Production and calibration of operating reference blocks 7 Calibration schedule 8 Identification 9 Records . 10 Availability . 11 Disputes Annex A (informative) Page 3 3 3 4 4 5 6 6 7 7 7 8 AECMA PRE
9、N*2004-7 96 W LOL23LL OOLOb8b 3TT Page 3 EN 2004-7 : 1996 1 Scope This standard defines different types of electrical conductivity reference blocks, to be used for the calibration of eddy current conductivity measuring equipment, their method of production and Cali bration. It is to be used in conju
10、nction with EN 2004-1. 2 Normative references This European Standard incorporates by dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent a
11、mendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. IS0 1 O01 2-1 Quality assurance requirements for measuring equipment - Part
12、1 : Metrological confirmation system for measuring equipment EN 2004-1 Aerospace series - Test methods for aluminium and aluminium alloy products - Part 1 Determination of electrical conductivity of wrought aluminium alloys 3 Definitions For the purposes of this standard the following definitions ap
13、ply : 3.1 Master reference standards A set of electrical conductivity reference standards, held by a National Standards Laboratory or an Accredited Laboratory and traceable to electrical reference standards. This set is maintained as the reference standard against which all the corresponding seconda
14、ry reference blocks shall be calibrated. 3.2 Secondary reference blocks Sets of electrical conductivity reference blocks calibrated by a National Standards Laboratory or an Accredited Laboratory against its master reference standards using eddy current conductivity measuring equipment. Individual co
15、mpanies or organisations may hold sets of secondary reference blocks. These blocks are the means by which traceability to the master reference standards is maintained. 3.3 Operating reference blocks Sets of electrical conductivity reference blocks prepared and calibrated by competent personnel again
16、st secondary reference blocks using eddy current conductivity measuring equipment. The operating reference blocks are used for routine instrument calibration. AECMA PREN+2004-7 96 m LOL23LL ROLOb7 236 m Page 4 EN 2004-7 : 1996 4 Production and calibration of master reference standards 4.1 The master
17、 reference standards shall be taken from wrought material of an appropriate electrical conductivity, in a stable metallurgical condition and whose electrical conductivity homogeneity at the surface and through the thickness has been verified (see 4.3). The surface roughness shall not exceed a value
18、of Ra = 1,6 pm. 4.2 Calibration shall be carried out at a temperature of 20 OC f 2 OC, using a method which ensures traceability to electrical standards. The result shall be normalized to a temperature of 20,oo OC. 4.3 All appropriate precautions shall be taken to ensure that variations of electrica
19、l conductivity (measured by an eddy current method) at the surface of any standard do not exceed 0,05 MS/m, and that variations associated with a frequency change over a range of 1 O kHz to 1 O0 kHz do not exceed 0,05 MS/m. 5 Production and calibration of secondary reference blocks 5.1 The secondary
20、 reference blocks shall be taken from wrought material of an appropriate electrical conductivity, in a stable metallurgical condition and whose homogeneity at the surface and through the thickness has been verified. They shall preferably be taken from the same material as that used to produce the ma
21、ster reference standards. The surface roughness shall not exceed a value of Ra = 1,6 pm. 5.2 The secondary reference blocks shall consist of square or circular samples with a thickness of at least 4 mm and sides or diameter of at least 30 mm. However, the dimensions shall be large enough compared wi
22、th the probe area in order to avoid edge effects. 5.3 The secondary reference blocks shall be calibrated against master reference standards using properly calibrated eddy current conductivity measuring equipment. The calibration shall be performed at 20 OC f 2 OC using the normalized conductivity va
23、lue of the master reference standards for comparison. The values shall be normalised to a temperature of 20,OO OC. The secondary reference blocks shall be calibrated at a frequency, within the calibrated range of the master reference standards, as required by the purchaser of these blocks (usually 6
24、0 kHz). 5.4 The secondary reference blocks shall be available as a set of at least four blocks of electrical conductivity values covering the whole range required for the calibration of operating reference blocks. Additional blocks may be required to ensure a finer coverage of some frequently used r
25、anges. 5.5 When the secondary reference blocks are anodised for protection (anodised layer between 10 pm and 15 pm on aluminium alloy blocks) the corresponding lift-off effect shall be taken into account and appropriate means devised to compensate for it when calibrating against the master reference
26、 standards. 5.6 The secondary reference blocks shall be supplied together with a certificate of measurement issued by a National Standards Laboratory or an Accredited Laboratory stating the electrical conductivity values registered in MS/m, the test frequency used and the temperature at which the va
27、lues have been normalized. The maximum overall uncertainty (at 95 % confidence limit) of the stated electrical conductivity values shall not exceed f 0,7 %. AECMA PREN*Z04-7 96 LOLZ3LL OOLObBB 172 Page 5 EN 2004-7 : 1996 6 Production and calibration of operating reference blocks 6.1 To avoid undue w
28、ear on secondary reference blocks, it is recommended that sets of operating reference blocks be used for the routine calibration of conductivity measuring equipments. The surface roughness shall not exceed a value of Ra = 1,6 pm. 6.2 The operating reference blocks shall normally be taken from wrough
29、t material of an appropriate electrical conductivity, in a stable metallurgical condition and whose uniformity of electrical conductivity over the surface has been verified. The material chosen shall exhibit no permanent change in electrical conductivity values as a result of storage or operating co
30、nditions. They shall be of such shape, size and finish that inaccuracies due to edge-effect and lift-off are avoided with the particular instrument to be calibrated. Their thickness shall be appropriate for the intended test frequency (see EN 2004-1). 6.3 The calibration of operating reference block
31、s shall be carried out by comparison against a set of secondary reference blocks. The calibration shall be carried out at the same frequency as that intended for routine testing (usually at a frequency of 60 kHz). 6.4 The calibration of the operating reference blocks shall be carried out using the f
32、ollowing method : - measurements shall be carried in a temperature-controlled environment at 20 OC I 2 OC; the actual temperature variation during this calibration shall be within k 0,5 OC. - an eddy current, comparison type conductivity meter operating at the required frequency shall be used (see 6
33、.31, - sufficient time shall be allowed for the operating and secondary reference blocks, the eddy current conductivity meter and the probe to reach ambient temperature (unnecessary handling of the blocks shall be avoided), - using the eddy current electrical conductivity meter, record the indicated
34、 values for a set of secondary reference blocks. The meter reading shall indicate the certified value k 0,2 MS/m or k 0,3 % IACS (International Annealed Copper Standard). If this is not the case then the eddy current electrical conductivity meter shall not be used for calibration of operating refere
35、nce blocks 1). 1) Non linear interpolation techniques may be used to compensate for a non linear response of the instrument. - - AECMA PRENu2004-7 96 = 3032333 0030689 O09 Page 6 EN 2004-7 : 1996 - read and record the conductivity of each applicable operating reference block. Conductivity readings s
36、hall be considered valid if they fall within a range of f 2 MS/m or I3,5 % IACS from the electrical conductivity of the applicable secondary reference block. When electrical conductivity readings fall outside the range of f 2 MS/m or k 3,5 % IACS then the electrical conductivity values to be used sh
37、all be determined by linear interpolation .e. using the formula : Co = Cl + c2 - (So-S1) s2 - SI where : CO is the calibrated conductivity of the operating reference block ; CI is the calibrated conductivity of the next lower secondary reference block ; C2 is the calibrated conductivity of the next
38、higher secondary reference block ; SO is the electrical conductivity meter scale reading for the operating reference block (mean value of five measurements) ; SI is the electrical conductivity meter scale reading for the next lower secondary reference block (mean value of five measurements) ; S2 is
39、the electrical conductivity meter scale reading for the next higher secondary reference block (mean value of five measurements). 6.5 method according to IS0 10012-1. The uncertainity of the reference block calibration shall be evaluated using an appropriate 7 Calibration schedule 7.1 Secondary refer
40、ence blocks shall be calibrated at intervals not exceeding four years. The interval shall be shorter if there is any reason for it (see 7.3). The National Standards Laboratory or the Accredited Laboratory shall provide a calibration service for secondary reference blocks. 7.2 method defined in 6.4.
41、Operating reference blocks shall be calibrated at intervals not exceeding 13 months by the 7.3 is suspect for any reason shall be re-calibrated before further use. Any reference block which has been exposed to excessive heat, mechanical damage, wear or 8 Identification All reference blocks shall be
42、identified with a unique indelible identification number or mark. Conductivity values and next calibration date shall be indicated on the sets. AECMA PREN*2004-7 96 = 10L23LL OOLOb90 820 Page 7 EN 2004-7 1996 9 Records Calibration records shall be kept for each reference block in accordance with app
43、ropriate Quality Procedures, and shall include the following : identification of reference block, nominal conductivity value, uncertainity on this conductivity value, type of block (e.g. secondary) date of Calibration, identification of apparatus and reference blocks used during calibration, tempera
44、ture of calibration, frequency of calibration, results normalized calibration values (where appropriate). 1 O Availability The list of Accredited Laboratories from which sets of secondary reference blocks may be purchased is given in annex A. 11 Ois putes Should any dispute arise as to the conductiv
45、ity of any reference block, the disputed block should initially be compared with another appropriate secondary reference block. Should the dispute not be resolved in this way, a National Standards Laboratory or an Accredited Laboratory shall be agreed by all parties to compare the disputed secondary
46、 reference block with a master reference set. AECMA PREN*200Y-? 96 W LOL23LL OOLOb9L 767 = National Standards Laboratory Page 8 EN 2004-7 : 1996 Range of secondary reference blocks currently available and nominal electrical conductivity values Annex A (informative) National Standards Laboratories which can provide secondary reference blocks National Physical Laboratory Division of Electrical Science Teddington Middlesex United Kingdom, TWI 1 OLW Set of 7 secondary reference blocks with nominal values of (59, 35, 29, 23, 19, 15 and 11 1 MS/m.
