ISO 7743:2011 pdf free download – Rubber, vulcanized or thermoplastic一 Determination of compression stress- strain properties.
C.1 Inspection
Before any calibration is undertaken, the condition of the items to be calibrated shall be ascertained by inspection and recorded on any calibration report or certificate. It shall be reported whether calibration is carried out in the “as-received” condition or after rectification of any abnormality or fault.
It shall be ascertained that the apparatus is generally fit for the intended purpose, including any parameters specified as approximate and for which the apparatus does not therefore need to be formally calibrated. If such parameters are liable to change, then the need for periodic checks shall be written into the detailed calibration procedures.
C.2 Schedule
Verification/calibration of the test apparatus is a mandatory part of this International Standard. However, the frequency of calibration and the procedures used are, unless otherwise stated, at the discretion of the individual laboratory, using ISO 18899 for guidance.
The calibration schedule given in Table C.1 has been compiled by listing all the parameters specified in the test method, together with the specified requirement. A parameter and requirement can relate to the main test apparatus, to part of that apparatus or to an ancillary apparatus necessary for the test.
For each parameter, a calibration procedure is indicated by reference to ISO 18899, to another publication or to a procedure particular to the test method which is detailed (whenever a calibration procedure which is more specific or detailed than that in ISO 18899 is available, it shall be used in preference).
The verification frequency for each parameter is given by a code letter. The code letters used in the calibration schedule are:
C requirement to be confirmed, but no measurement;
S standard interval as given in ISO 18899:
U in use.
An interlaboratory test programme (ITP) for evaluating precision of compression modulus was conducted in 2008 using the precision procedures and guidelines described in ISOITR 9272.
See ISOITR 9272 for other details and terminology on precision evaluation.
Compression modulus measurement methods A and 0 were evaluated. A Type 1 precision was evaluated using cured test pieces prepared from nine different rubber-compound test piece combinations (with a range of values) supplied to each of the eight participating laboratories in the ITP. The nine compounds are designated as compounds A, B, C for Method A (for two different strain levels); D, E, F for Method D (profile) and G, H and I for method D (0-ring). On each of two test days, one week apart, the following test sequence was carried out. Three measurements for each compound test piece were conducted and a median of the three measurements was obtained. The median value is defined as a test result for that test day. All analysis was conducted on the basis of test result data (i.e. median of three for any day). The ISO/TR 9272[i Option 1 outlier treatment procedure, outlier deletion, was used.
The precision results as determined by this ITP may not be applied to acceptance or rejection testing for any group of materials or products without documentation that the results of this precision evaluation actually apply to the products or materials tested.
D.2 Precision results
D.2.1 General. The precision results for all methods and compounds for compression modulus are given in Table D.1. These results were obtained using the outlier deletion as noted above. General statements for the use of the precision results are cited below. These are given in terms of both the absolute precision, r or R, and also for relative precision (r) and (R).
D.2.2 Repeatability. The repeatability, or local domain precision, for each of the compression modulus test methods has been established for each compound or material and method by the values found in Table D.1. Two individual test results (obtained by the proper use of this International Standard) that differ by more than the tabulated values for r, in measurement units, and (r), as a percentage of the mean level, should be considered suspect, i.e. to have come from different populations. Such a decision suggests that some appropriate investigative action be taken.
D.2.3 Reproducibility. The reproducibility, or global domain precision, for each of the compression modulus test methods has been established for each compound or material and method by the values found in Table Di, Two individual test results obtained in different laboratories (by the proper use of this International Standard) that differ by more than the tabulated values for R, in measurement units, and (R), as a percentage of the mean level, should be considered suspect, i.e. to have come from different populations.