ASTM D2176-16 (R2021) pdf free download.Standard Test Method for Folding Endurance of Paper and Plastics Film by the M.I.T. Tester.
1 .1 This test method describes the use of the M.I.T.-type folding apparatus for determining folding endurance of paper and plastics film. The M.I.T. tester can he adjusted for samples of any thickness: however, if the outer layers thicker than about 0.25 mm (0.01 in.) rupture during the first few folds, the test loses its significance. The procedure for the Schopper-type apparatus is given in Test Method DM3.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.
3. Terminology
3.1 Definitions shall be in accordance with Terminology D 1968 and the Dictionary of Paper.4
4. Significance and Use
4.1 The folding endurance is frequently used to estimate the ability of the paper and plastics film to withstand repeated bending, folding. and creasing.
4.2 Folding endurance has also been found useful in measuring the deterioration of paper and plastics film upon aging.
5. Apparatus
5. 1 Folding Testei; consisting of:
5.1.1 A spring-loaded clamping jaw constrained to move without rotation in a direction perpendicular to the axis of rotation of the folding head specified below and having its clamping surfaces in the plane of this axis. The load is applied by a spring attached to the jaw assembly which is easily adjustable to provide any desired tension on the specimen within range of 4.9 to 14.72 N (500 to 1500 gf). The deflection of the spring when loaded shall be at least 17 mm (0.67 in.)/9.81 N. which is achieved by using a weight of 1 kg mass.
5.1.2 An oscillating folding head supporting two smooth, cylindrical folding surfaces parallel to, and symmetrically placed with respect to. the axis of rotation. Each of the two folding surfaces shall have a radius of’ curvature of’ 0.38 mm (0.015 ± 0.001 in.) and a width of 19 mm (0.75 ± 0.04 in).ASTM D2176 pdf download.