1、November 2006DEUTSCHE NORM Translation by DIN-Sprachendienst.English price group 6No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (D
2、IN-Normen).ICS 59.140.30!$IT“1382549www.din.deDDIN 53359Testing of imitation leather and similar sheet materials Flex cracking testPrfung von Kunstleder und hnlichen Flchengebilden Dauer-KnickversuchSupersedesDIN 53359:1957-11www.beuth.deDocument comprises 7 pagesIn case of doubt, the German-languag
3、e original should be consulted as the authoritative text.DIN 53359:2006-11 2 Foreword This document has been prepared by Technical Committee NA 054-04-04 AA Kunststoff-Folien und kunststoffbeschichtete Flchengebilde (Kunstleder); allgemeine Eigenschaften of the Normenausschuss Kunststoffe (Plastics
4、Standards Committee). Amendments This standard differs from DIN 53359:1957-11 as follows. a) The title has been changed. b) The scope has been extended to include “imitation leather and similar sheet materials”. c) Normative references have been included. d) The assessment after a predefined number
5、of flexes has been included. e) The standard has been editorially revised. Previous editions DIN 53359: 1957-11 Introduction Although the withdrawal of DIN 53359:1957-11 had previously been announced, the publication of a revised edition became necessary since the flexing test it specifies is includ
6、ed in the delivery conditions of a number of important customers. DIN 53359:2006-11 3 1 Scope The test specified in this standard serves to assess the behaviour of products as in DIN 16922 when subjected to repetitive flexing (flex cracking behaviour). The test specimens may be of type A or type B (
7、see clause 4), although results obtained for the two types are not comparable. Whether type A or type B test specimens are to be tested and at what temperature shall be subject to agreement. 2 Normative references The following referenced documents are indispensable for the application of this docum
8、ent. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. DIN 16906, Testing of plastic sheeting and plastic films Sample and specimen Preparation and conditioning DIN 16922, Flexible sheet mat
9、erials manufactured using plastics Technological classification DIN EN ISO 291, Plastics Standard atmospheres for conditioning and testing DIN EN ISO 2286-3, Rubber- or plastic-coated fabrics Determination of roll characteristics Part 3: Method for determination of thickness 3 Terms and definitions
10、For the purposes of this standard, the following term and definition applies. 3.1 flex number the number of flexes under defined test conditions at which the first crack becomes visible on a test specimen viewed through a magnifying glass having a magnification of 6 4 Samples and test specimens 4.1
11、Sampling and conditioning Sampling and conditioning shall be carried out as specified in DIN 16906. 4.2 Type and number of test specimens Out of each sample, cut five test specimens each parallel to, perpendicular to and, if so agreed, diagonal to the direction of extrusion. Type A test specimen (fo
12、r testing as in Figures 1 and 2): 20 mm 40 mm, DIN 53359:2006-11 4 Dimensions in millimetres Key 1 Test specimen (20 mm 40 mm) Figure 1 Type A test specimen clamped, unflexed Key 1 Test specimen Figure 2 Type A test specimen clamped, flexed Type B test specimen (for testing as in Figures 3 and 4): 4
13、0 mm 40 mm Dimensions in millimetres Side view of test specimen Key 1 Test specimen (40 mm 40 mm, or 20 mm 40 mm when folded) Figure 3 Type B test specimen clamped, unflexed DIN 53359:2006-11 5 Key 1 Test specimen Figure 4 Type B test specimen clamped, flexed 5 Apparatus 5.1 Flexing machine Testing
14、shall be carried out with a flexing machine having a grip travel that can be adjusted from 0 mm to 20 mm and is capable of performing 200 flexes per minute and equipped with a counter for displaying the number of flexes. 5.2 Grips Grips shall be designed so that test specimens can be firmly clamped
15、without their grip end faces imposing a mechanical load on the test specimen when flexed (see Figures 2 and 4). The thickness of the end faces shall be such as to exceed the dimensions of the outward fold of the test specimens. 5.3 Temperature control device If testing in a test atmosphere other tha
16、n the standard atmosphere is agreed: a temperature control device capable of maintaining the selected temperature to within 2 K throughout the test. 5.4 Magnifying glass Magnifying glass having a magnification of 6 (e.g. magnifying glass as in DIN EN ISO 15253). 6 Procedure 6.1 Setting the test temp
17、erature Unless otherwise agreed, perform the test in a DIN EN ISO 291 23/50-2 standard atmosphere. If a different test temperature is agreed, prior to testing condition the test specimen, clamped as in 6.3, for at least one hour at the test temperature. 6.2 Sample thickness measurement Measure the t
18、hickness, h, of the test specimen as specified in DIN EN ISO 2286-3. DIN 53359:2006-11 6 6.3 Setting the grip travel Set the grip travel of the flexing machine so that the minimum separation between the end faces of the grips is twice the thickness of type A test specimens, or four times the thickne
19、ss of type B test specimens (in both cases when clamped) plus an additional 2 mm; the maximum separation shall be 20 mm. Type A test specimens After conditioning the test specimens as specified in clause 4, clamp them in the grips of the flexing machine with a clearance of 20 mm (see Figure 1), taki
20、ng care not to prestress or compress them. Type B test specimens After conditioning the test specimens as specified in clause 4, fold them with the side to be assessed facing outwards and so that they measure 20 mm 40 mm before being clamped in the flexing machine as shown in Figure 3. 6.4 Determina
21、tion of flex number To determine the flex number, assess the test specimens at intervals corresponding to the geometrical series shown in the following table. Assess after the following numbers of flexes: 1 250 2 000 3 150 5 000 8 000 12 500 20 000 31 500 50 000 80 000 125 000 200 000 315 000 500 00
22、0 Look for cracks in the samples by examining them while still in the flexing machine using a magnifying glass with a magnification of 6 and adequate lighting, adjusting the separation between the grips manually so that all the possible folds can be carefully inspected. 6.5 Testing with a fixed numb
23、er of flexes If a specific number of flexes has been agreed in delivery conditions, stop the test when that number has been reached and examine the test specimen with a magnifying glass having a magnification of 6 to determine whether it is undamaged or has developed cracks. 7 Test report The test r
24、eport shall include the following details: a) a reference to this standard; b) type and designation of product tested; c) type of test specimen; d) test atmosphere; e) separate flex numbers for the longitudinal and transverse directions or assessment as in 6.5; f) any deviations from this standard; g) date of testing. DIN 53359:2006-11 7 Bibliography DIN EN ISO 15253, Ophthalmic optics and instruments Optical devices for enhancing low vision
