ASTM D2176-16(2021)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D2176 − 16 (Reapproved 2021)
Standard Test Method for
Folding Endurance of Paper and Plastics Film by the M.I.T.
Tester
This standard is issued under the fixed designation D2176; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope D643 Test Method for Folding Endurance of Paper by the
Schopper Tester (Withdrawn 2010)
1.1 This test method describes the use of the M.I.T.-type
D685 Practice for Conditioning Paper and Paper Products
folding apparatus for determining folding endurance of paper
for Testing
and plastics film. The M.I.T. tester can be adjusted for samples
D1968 Terminology Relating to Paper and Paper Products
ofanythickness;however,iftheouterlayersthickerthanabout
E122 Practice for Calculating Sample Size to Estimate,With
0.25 mm (0.01 in.) rupture during the first few folds, the test
Specified Precision, the Average for a Characteristic of a
loses its significance. The procedure for the Schopper-type
Lot or Process
apparatus is given in Test Method D643.
1.2 The values stated in SI units are to be regarded as 3. Terminology
standard. The values given in parentheses are mathematical
3.1 Definitions shall be in accordance with Terminology
conversions to inch-pound units that are provided for informa- 4
D1968 and the Dictionary of Paper.
tion only and are not considered standard
4. Significance and Use
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 The folding endurance is frequently used to estimate the
responsibility of the user of this standard to establish appro-
ability of the paper and plastics film to withstand repeated
priate safety, health, and environmental practices and deter-
bending, folding, and creasing.
mine the applicability of regulatory limitations prior to use.
4.2 Folding endurance has also been found useful in mea-
1.4 This international standard was developed in accor-
suring the deterioration of paper and plastics film upon aging.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
5. Apparatus
Development of International Standards, Guides and Recom-
5.1 Folding Tester, consisting of:
mendations issued by the World Trade Organization Technical
5.1.1 A spring-loaded clamping jaw constrained to move
Barriers to Trade (TBT) Committee.
without rotation in a direction perpendicular to the axis of
rotation of the folding head specified below and having its
2. Referenced Documents
clamping surfaces in the plane of this axis. The load is applied
2.1 ASTM Standards:
by a spring attached to the jaw assembly which is easily
D585 Practice for Sampling and Accepting a Single Lot of
adjustable to provide any desired tension on the specimen
Paper, Paperboard, Fiberboard, and Related Product
within range of 4.9 to 14.72 N (500 to 1500 gf). The deflection
(Withdrawn 2010)
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,
ThisclassificationsystemisunderthejurisdictionofASTMCommitteeD20on
cylindrical folding surfaces parallel to, and symmetrically
Plastics and is the direct responsibility of Subcommittee D20.15 on Thermoplastic
Materials. placed with respect to, the axis of rotation. Each of the two
Current edition approved July 1, 2021. Published July 2021. Originally approved
folding surfaces shall have a radius of curvature of 0.38 mm
in 1956. Last previous edition approved in 2016 as D2176 - 16. DOI: 10.1520/
(0.015 6 0.001 in.) and a width of 19 mm (0.75 6 0.04 in).
D2176-16R21.
The distance separating the folding surfaces is greater than the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Available from Technological Association of the Pulp and Paper Industry
The last approved version of this historical standard is referenced on (TAPPI), 15 Technology Parkway South, Suite 115, Peachtree Corners, GA 30092,
www.astm.org. http://www.tappi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2176 − 16 (2021)
uncompressed thickness of the specimen being tested by no free of wrinkles or blemishes. The portion of the test specimen
more than 0.25 mm (0.010 in.). The position of the axis of where folding will occur must be free of any portion of a
rotation is midway between the common tangent planes of the watermark and have opacity and formation typical of the
two folding surfaces. The folding head is provided with a sample. Because the folding process occurs over a very short
clamping jaw with its nearest edge not less than 9.5 mm (0.375 length of the total test specimen (that is, at the line of fold),
in.) beyond the axis of rotation. The rotary oscillating move- data precision is heavily dependent upon the care taken in test
ment of the head is such as to fold the specimen through an specimen selection and preparation.
angle of 135 6 2°, both to the right and to the left of the
9. Instrument Maintenance and Calibration
position of the unfolded specimen.
5.1.3 Various size folding heads are required for testing
9.1 The folding test results are very sensitive to tension, arc
different thicknesses of specimens. Heads available will ac-
of fold, and radius of fold; therefore it is essential that regular
commodate thicknesses from 0 to 0.25 mm (0 to 0.01 in.), 0.25
calibration routines be established and followed.
to 0.50 mm (0.01 to 0.02 in.), 0.50 to 0.75 mm (0.02 to 0.03
9.2 Make sure that the folding edges are free from rust,
in.), 0.75 to 1.02 mm (0.03 to 0.04 in.), and 1.02 to 1.25 mm
nicks, dirt, and oil and that the counter operates properly.
(0.04 to 0.05 in.).
9.3 Measure the plunger friction by determining the addi-
5.2 Power Driven Device, for imparting a rotary oscillating
tional load required to move the plunger perceptibly under a
motion of 175 6 25 cycles/min to the folding clamp.
load of 9.81 N or the load tension used for the testing. This
5.3 Counter, for registering the number of double folds
shall not be greater than 0.245 N (25 gf).
required to break the specimen and a device to stop the
9.4 The change in tension due to the eccentricity of rotation
instrument when the specimen breaks.
of the folding edges is measured as follows: Place a test
5.4 Strip Cutter, to cut 15-mm wide parallel strips within
specimen of the proper thickness, cut in the machine direction,
60.02 mm with clean edges.
in the tester as for making a folding test, and apply a tension of
9.81Northattobeusedforthetesting.Rotatethefoldinghead
5.5 A means for controlling the temperat
...