BS ISO 21546 pdf free download

BS ISO 21546-2019 pdf free download.Paints and varnishes – Determination of the resistance to rubbing using a linear abrasion tester (crockmeter).
5 Apparatus and ancillary materials
5.1 Linear abrasion tester (crockmeter)
Linear abrasion tester in accordance with Figure 1. which is specified by the following properties.
5.1.1 The mechanism can be manual (as illustrated in Figure 1) or (electro) motor driven.
5.1.2 For the motoric version, an operation counter for pre-setting the number of double-strokes shall be integrated and the mechanism shall have a stroke frequency of(1,0 ± 0,1) Hz and shall have a constant velocity within the 70 mm measurement area.
5.1.3 The test load with which the abrasion tool (5.12) is pressed onto the test specimen shall be (9,0 ± 0.2) N (for abrasion tool B and C) and (2 2,0 ± 05) N (for abrasion tool A).
NOTE Test devices intended for a test load of 9,0 N can be converted to a test load of 22,0 N by means of an additional load of 13.0 N (corresponding to an additional weight with a mass of 1,33 kg).
5.1.4 The stroke length shall be selected in such a way that the length of the assessable friction mark is (100 ± 30) mm.
NOTE 1 The assessable friction mark equals the total friction mark, less the expansion of the contact surface of the abrasion tool in the direction of the stroke on both ends (see 73.1). Consequently, the stroke length is at least 70 mm + 2 x expansion, in millimetres, of the contact surface of the abrasion tool in the direction of the stroke. For the dimensions of the abrasion tools, see 52.
NOTE 2 Some devices exist with a length of the assessable surface less than 70 mm due to technical reasons.
5.2 Abrasion tool
5.2.1 Abrasion tool A, e.g. as shown in Figure 2 a). The felt insert shall have the dimensions (22,0 ± 0.2) mm x (22,0 ± 0.2) mm x 6 mm and a bulk density of 0.44 g/cm3. The coupling with the crockrneter (ii) is rigid.
NOTE Despite the rigid coupling a tilting of the front face of the abrasion tool A against the test specimen is impossible due to the elastic felt insert.
5.2.2 Abrasion tool B, designed as a cylinder with a diameter of (16,0 ± 0.1) mm, the front surface of which is facing the test specimen. The coupling with the crockmeter (5.1) is rigid.
NOTE 1 Due to the rigid coupling a tilting of the front surface of the abrasion tool B against the test specimen is generally possible.
NOTE 2 Unlike abrasion tools A and C, abrasion tool B cannot be lined with abrasive material without wrinkling.
5.2.3 AbrasIon tool C. e.g. as shown in Figure2 b). The radius of the tool shall be (19,0 ± 0,5) mm and a width of (25,0 ± 0.3) mm. In the contact area to the test specimen, the lateral surface of the tool shall be covered with a layer of EPDM rubber3), e.g. DIM ZK EPDM 2 1606l, with a thickness of(3,0 ± 0,3) mm and a width of (25.0 ± 0,3) mm. and which has the hardness of (60 ± 5) Shore-00 in accordance with ASTM D2240 and a bulk density of (0.16 ± 0,02) g/cm3 in accordance with ISO 845. The coupling with the crockmeter (5.1) can be moved across the direction of the stroke (see view II in Figure2 b))
When lining the abrasion tool with the abrasive material (5.3). the latter is attached Lightly to the abrasion tool by means of roll pins which are elastically interconnected by the rubber strips (see view III in Figure 2 b).
NOTE 1 Due to the EPDM rubber cover the effective diameter of the tool is 44 mm.BS ISO 21546 pdf download.