ISO 48:2010 pdf free download – Rubber, vulcanized or thermoplastic – Determination of hardness (hardness between 10 IRHD and 100 IRHD).
d) High-hardness rubbers (method H). Three rubber compounds, nominal hardness range 85 IRHD to 100 IRHD, 12 laboratories. Three determinations (measurements) of hardness on each of two days, one week apart, using method H. The median of the three was used as the “test result” for the precision analysis.
e) Low-hardness rubber (method L). One rubber compound of nominally low hardness, five laboratories. Three determinations (measurements) of hardness on each of two days, one week apart, using method L. The median of the three was used as the “test result” for the precision analysis.
B.2..1.2 The precision assessments are type 1 (cured, prepared test pieces circulated) and the time for repeatability and reproducibility is on a scale of days. For the low-hardness rubber, method L, due to the small number of laboratories in the precision evaluation programme the tabulated precision results should be used with caution.
B.2.2 Precision results (1985 to 1989)
B.2.2.1 The precision results are given in Table B.1 for medium-hardness rubbers using method N, Table B.2 for medium-hardness rubbers using method M, Table B.3 for high-hardness rubbers using method N, Table B.4 for high-hardness rubbers using method H, and Table B.5 for the low-hardness rubber using method L.
B.2.2.2 The precision results as determined by this ITP should 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.
B.3.1 Programme details
B.3.1.1 An ITP for the evaluation of the precision of micro hardness tests was conducted in 2004, using the procedures and guidelines described in ISO/TR 9272:2005. Precision for the microtest method was determined for the purposes of comparison with Shore AM hardness determined in accordance with
ISO 7619-1.
B.3.1.2 A type 1 precision was evaluated (for both methods), using cured test pieces prepared from four different rubber compounds, A, B, C and D (with a range of hardnesses), supplied to each of the six laboratories participating in the ITP. On each of two test days, two weeks apart, the following test sequence was carried out.
B.3.1.3 For each compound, three test pieces were furnished and five hardness measurements were made on each of the three test pieces by each of two operators. For each operator, a median value was selected for the three test pieces. The two median values were then averaged to obtain a single value designated as the test result for that test day. Shore AM measurements were made on one side of the test piece and IRHD measurements were made on the reverse side. The precision analysis was based on the test result data, i.e. two test result values per laboratory.
B.3.1.4 The ISOITR 9272:2005 option 2 outlier treatment procedure, outlier replacement, was used since the ITP had only the minimum number of participating laboratories (six). This option 2 procedure replaces each outlier declared as significant with a value that is consistent with the data-value distribution for the nonoutlier data for that material. See ISO/TR 9272:2005 for the rationale of this concept and for other details.
B..3.1.5 The precision results as determined by this ITP should 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.
B.3.2 Precision results (2004)
B.3.2.1 The precision results obtained for the IRHD microtest method are given in Table B.6, with the materials listed in increasing order of hardness. The results are given in terms of both the absolute precision, r or R, and the relative precision, (r) and (R).