ASTM D2176:16(R2021) pdf free download – Standard Test Method for Folding Endurance of Paper and Plastics Film by the M.I.T. Tester.
10.3 Set the counter to zero and place the centrifugal fan so that its inlet is almost touching and is across the specimen and oscillating head. Start the fan and the instrument motor. Fold the strip at a uniform rate of 175 25 double folds per minute until it breaks. Record the number of double folds made before fracture. If there is any appreciable delay between tests on successive specimens. keep the fan running to prevent the head warming by conduction from its shaft.
11. Report
11.1 For each test specimen record the number of double folds for the machine and cross directions. Convert the raw data to the logarithm (base 10). Calculate the mean of the logs and report as log10 MIT folding endurance for each direction separately. to two significant figures for the mantissa. State clearly if a tension other than 9.81 N (1 kgf) was used. Include the number of specimens tested, and the standard deviation of (he log10 of the fold number obtained in each direction.
11.2 Alternate report permitted. Although the preferred method for reporting MIT folding endurance is that in 11.1, an alternate procedure of reporting the mean of the number of double folds and the standard deviation for the machine and cross directions of the specimen separately is permitted.
11.3 Tests made on strips having their length in the machine direction are designated as being the ‘6machine direction,” and similarly for the cross direction.
12. Precision and Bias
1 2. 1 Precision.
12.1.1 The repeatability standard deviation for folding endurance of paper has been determined to be 20 % and the reproducibility standard deviation for folding endurance has been determined to be 28 %.
12.1 .2 The repeatability standard deviation for folding endurance of plastic film has been determined to he 15 % and the reproducibility standard deviation for folding endurance has been determined to be 20 %.
12.2 Bias:
12.2.1 No information can be presented regarding the bias of fold endurance by the M.I.T. tester, as the measured value is defined by the procedure in the test method. No Information is given regarding the bias between folding endurance as measured in this test method using the M.I.T. tester and that measured in Test Method DM3 using the Schopper Tester because the instruments apply folding stress to the test spedmen in different ways and the relationship between results by the two procedures is not a constant value.
13. Keywords
13.1 fold number; folding endurance; paper; plastics film.