5.1 This test guide provides a means to quantify the abrasion resistance of material surfaces, and may be related to end-use performance, or used to comparatively rank material performance, or both. The resistance of material surfaces to abrasion, as measured on a testing machine in the laboratory, is generally only one of several factors contributing to wear performance as experienced in the actual use of the material. Other factors may need to be considered in any calculation of predicted life from specific abrasion data.

5.2 The resistance of material surfaces to abrasion may be affected by factors including test conditions; type of abradant; pressure between the specimen and abradant; mounting or tension of the specimen; and type, kind, or amount of finishing materials.

5.3 Abrasion tests utilizing the rotary platform abraser may be subject to variation due to changes in the abradant during the course of specific tests. Depending on abradant type and test specimen, the abrading wheel surface may change (that is, become clogged) due to the pick-up of finishing or other materials from test specimens. To reduce this variation, the abrading wheels should be resurfaced at regularly defined intervals. See Appendix X2.

5.4 When evaluating resistance to abrasion of two or more coatings, other factors may need to be considered for an accurate comparison. Flexible coatings that include air entrainment bubbles may result in less mass loss. Coatings that include fillers may result in greater mass loss but have less change in coating thickness or less mass loss but have greater change in coating thickness. Coatings that include aggregates or particulates may generate wear debris that is not removed by the vacuum and contribute to the break-down of the coating. Coatings that have a hardness value greater than the abrasive wheel may cause the abrasive wheel to break down faster and require more wear cycles to generate measureable wear. Examples of coatings that may be impacted include epoxies, polymethyl-methacrylate (PMMA), polyurethane-methacrylate (PUMA), methyl-methacrylate (MMA), and carbon resin.

Note 1: As an example, consider a urethane coating of 0.5?mm thickness, embedded with 1.2?μm titanium particles that resulted in a 53?μm loss in coating thickness and 110?mg mass loss. A similar urethane coating without titanium particles resulted in a 78?μm loss in coating thickness and 44?mg mass loss.

5.5 The measurement of the relative amount of abrasion may be affected by the method of evaluation and influenced by the judgment of the operator.