ASTM_D_6988_-_21.pdf

Designation:D698821Standard Guide forDetermination of Thickness of Plastic Film Test Specimens1This standard is issued under the fixed designation D6988;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 guide covers the determination of the thickness ofplastic films where the thickness is used directly in determiningthe results of tests for various properties.Use this practiceexcept as otherwise required in material specifications or inapplicable test standards.NOTE1Film is defined in Terminology D883 as an optional term forsheeting having a nominal thickness no greater than 0.25 mm(0.010 in.).NOTE2Alternative methods are acceptable if they meet the require-ments of measurement precision as noted in this guide.NOTE3This guide is not intended to address the sampling techniquesor the measurement of film thickness for the commercial classification ofcommercial products or for quality control purposes.1.2 The values stated in SI units are to be regarded as thestandard.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.NOTE4This standard and ISO 4593 address the same subject matterbut differ in technical content.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensD6287 Practice for Cutting Film and Sheeting Test Speci-mens2.2 ISO Standard:ISO 472 PlasticsVocabulary33.Terminology3.1 DefinitionsSee Terminologies D883 and ISO 472 fordefinitions pertinent to this guide.3.2 Definitions of Terms Specific to This Standard:3.2.1 absolute uncertainty(of a measurement),nthesmallest division that can be read directly on the instrumentused for measurement.3.2.2 calibration,nthe set of operations that establishes,under specified conditions,the relationship between valuesmeasured or indicated by an instrument or system,and thecorresponding reference standard or known values derivedfrom the appropriate reference standards.3.2.3 dead-weight micrometer,nan instrument capable ofmeasuring the thickness of thin films utilizing a weight to applyuniform pressure to the specimen.3.2.4 verification,nproof,with the use of calibrated stan-dards or standard reference materials that the calibrated instru-ment is operating within specified requirements.4.Summary of Methods4.1 This guide describes four different methods for thethickness measurement of plastic film specimens.The methods(identified as Methods A,B,C,and D)use different microm-eters that actuate the weights in different manners or utilizedifferent means of reading the thickness.4.2 It is permissible to use other instruments,includingnon-contact instruments and instruments using alternativereadout systems in place of dials provided they meet or exceedthe precision requirements noted in this practice.5.Significance and Use5.1 This guide is intended to provide recommendations andsuggested good practices to determine precise dimensionswhen necessary for the calculation of properties expressed in1This guide is under the jurisdiction of ASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.19 on Film,Sheeting,and MoldedProducts.Current edition approved Oct.1,2021.Published November 2021.Originallyapproved in 2003.Last previous edition approved in 2013 as D6988-13.DOI:10.1520/D6988-21.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1physical units.It is not intended to replace practical thicknessmeasurements