ASTM_D_7027_-_20.pdf

Designation:D702720Standard Test Method forEvaluation of Scratch Resistance of Polymeric Coatings andPlastics Using an Instrumented Scratch Machine1This standard is issued under the fixed designation D7027;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.Scope*1.1 This test method describes a laboratory procedure usingan instrumented scratch machine to produce and quantifysurface damage under controlled conditions.This test methodis able to characterize the scratch resistance of polymers bymeasuring many significant material parameters.The scratch-inducing and data acquisition process is automated to avoiduser-influenced effects that may affect the results.1.2 The values stated in SI units are to be regarded asstandard.The values in parentheses are for information only.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.NOTE1This standard is equivalent to ISO 19252.1.4 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:2A276/A276M Specification for Stainless Steel Bars andShapesD618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD883 Terminology Relating to PlasticsD1894 Test Method for Static and Kinetic Coefficients ofFriction of Plastic Film and SheetingE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsG99 Test Method for Wear Testing with a Pin-on-DiskApparatusG171 Test Method for Scratch Hardness of Materials Usinga Diamond Stylus3.Terminology3.1 Terms used in this standard are defined in accordancewith Terminology D883,unless otherwise specified.For termsrelating to precision and bias and associated issues,the termsused in this standard are defined in accordance with Terminol-ogy E456.3.2 Definitions:3.2.1 ASV Software,nAutomatic Scratch Visualization,acomputer program which automates the identification of thepoint of failure in a rising load scratch tests using contrast asthe failure criteria.3.2.1.1 DiscussionTheASV software determines failure ifa continuous change in contrast between the scratch groove andthe undamaged material surface reaches+3%,-3%,or 63%.The continuity criterion is defined as a region of length equalto 2 diameters of the scratch stylus with 90%or more of theregion exceeding the contrast criterion.The lowest load pointon the scratch from which there is a continuous contrastingregion is considered the point of failure.This program is usefulfor visual analysis of the test and may be used for otherapplications,such as pass-fail criterion for scratch visibility.Anexample of the application of ASV is shown in Fig.1.3.2.2 critical normal load,nthe normal load at whichfailure(see 3.2.4)of the material within the scratch groove firstoccurs.3.2.3 normal load,na load applied onto the scratch stylusthat is imposed in a vertically downward direction,perpendicu-lar to the surface of the specimen.3.2.3.1 DiscussionThe normal load is also referred to asthe“Z-direction load.”3.2.4 point of failure,nthe point along a rising-loadscratch path at which the damage to the surface is firstconsidered to be unacceptable.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved Sept.1,2020.Published October 2020.Originallyapproved in 2005.Last previous edition approved in 2013 as D702713.DOI:10.1520/D7027-20.2For 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.*A Summary of Changes section appears at the end of this standardCopyright 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.3.2.4.1 DiscussionThe point of failure for a given studyshall be d