ASTM_D_643_-_97_2007.pdf

Designation:D643 97(Reapproved 2007)An American National StandardStandard Test Method forFolding Endurance of Paper by the Schopper Tester1This standard is issued under the fixed designation D643;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method describes the use of the Schopper typeof folding apparatus.It is suitable for papers having a thicknessof 0.25 mm(0.010 in.)or less.1.2 The procedure for the M.I.T.-type apparatus is given inTest Method D2176.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D585 Practice for Sampling and Accepting a Single Lot ofPaper,Paperboard,Fiberboard,and Related ProductD685 Practice for Conditioning Paper and Paper Productsfor TestingD776 Test Method for Determination of Effect of Dry Heaton Properties of Paper and BoardD1968 Terminology Relating to Paper and Paper ProductsD2176 Test Method for Folding Endurance of Paper by theM.I.T.TesterD4714 Test Method for Determination of Effect of MoistHeat(50%Relative Humidity and 90C)on Properties ofPaper and BoardE122 Practice for Calculating Sample Size to Estimate,With Specified Precision,the Average for a Characteristicof a Lot or Process2.2ISO Standard:ISO 5626 Paper Determination of Folding Endurance33.Terminology3.1 DefinitionsDefinitions shall be in accordance withTerminology D1968 and the Dictionary of Paper.44.Significance and Use4.1 Folding endurance is not a measure of the foldability ofpaper,but a measure of the strength of paper.In many cases,itis a better measure of strength than the conventional tests fortensile strength,bursting strength,and tearing resistance.Theuniqueness of the folding endurance tests leads to many specialuses for this test method.4.2 Folding endurance is determined by the number of timesthat the paper can be folded before it loses enough tensilestrength to break under the conditions of the test.It is the onlyone of the four strength tests that uses a repetitive mechanicaltreatment to weaken the sheet.Therefore,it is the only one ofthe strength tests that measures the durability of paper sub-jected to repeated or rough handling.It is an important test forpaper that will be subjected to continued folding and unfoldingduring use.Examples are maps and printed materials such asmusic,pamphlets,folded prints,and blueprints.It is also animportant test for any paper that will be handled repeatedly orwhich might be subjected to rough treatment when it is beingused.4.3 The ratio between the machine direction and crossdirection folding endurance is a good measure of the fiberorientation in the sheet.For most papers,the machine directiontest will be higher than the cross direction test,and the morethe fibers are oriented in the machine direction,the greater thedifference will be.If the cross direction is higher than themachine direction,the paper has an unusually large number offibers oriented in the cross direction.This information may alsobe obtained from tests for tensile strength and tearing resis-tance but the folding endurance test is much more sensitive tothese differences than the other two tests.4.4 Folding endurance is more sensitive to the flexibility inthe paper than the other strength tests.Because flexibility islost with aging,folding endurance is commonly used as anindicator of strength loss in accelerated aging tests.1This test method is under the jurisdiction of ASTM Committee D06 on Paperand Paper Products and is the direct responsibility of Subcommittee D06.92 onStandard Documents Relating to Paper and Paper Products.Current edition approved Dec.1,2007.Published December 2007.Originallyapproved in 1941.Last previous edition approved in 2002 as D643 97(2002).DOI:10.1520/D0643-97R07.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.4Available from Technical Association of the Pulp and Paper Industry(TAPPI),15 Technology Parkway South,Norcross,GA 30092,http:/www.tappi.org.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)for the latest information.4.5 The folding endurance