ISO 21546:2019 pdf free
ISO 21546:2019 pdf free.Paints and varnishes – Determination of the resistance to rubbing using a linear abrasion tester (crockmeter)
A loaded abrasion tool, lined with agreed abrasive material and influenced by an agreed abrasive medium, is moved over the coating using a linear abrasion tester (crockmeter). There are three procedure variations, depending on the agreement and application (see Table 1).
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.
The test load with which the abrasion tool (5.2) is pressed onto the test specimen shall be (9,0±0,2) N (for abrasion tool B and C) and (22,0±0,5) 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).
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 7.3.1). Consequently, the stroke length is at least 70 mm±2×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 5.2.
NOTE 2 Some devices exist with a length of the assessable surface less than 70 mm due to technical reasons.When lining the abrasion tool with the abrasive material (5.3), the latter is attached tightly to the abrasion tool by means of roll pins which are elastically interconnected by the rubber strips (see view II in Figure2 b).
NOTE 1 Due to the EPDM rubber cover the effective diameter of the tool is 44 mm.
NOTE 2 Due to the geometry of the abrasion tool and the movable coupling with the crockmeter, tests can be carried out on curved test specimens by means of abrasion tool C.
NOTE 3 Unlike abrasion tools A and B, the contact surface with the test specimen is geometrically unspecified for abrasion tool C; it is rather defined by the radius of the tool, the elastomer hardness, the test load, and, if applicable, by the properties of the abrasive material.ISO 21546 pdf free download.
