ASTM_F_548_-_09_2014.pdf

Designation:F54809(Reapproved 2014)Standard Test Method forIntensity of Scratches on Aerospace Transparent Plastics1This standard is issued under the fixed designation F548;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the visual inspection of shallowor superficial scratches on the surface of aerospace transparentplastic materials.1.2 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:2F428 Test Method for Intensity of Scratches on AerospaceGlass Enclosures3.Summary of Test Method3.1 A visual comparison is made between a set of gradedscratch standards and the scratch on the plastic material todetermine the relative intensity of the scratch.4.Significance and Use4.1 Scratches exist on all transparent plastic surfaces.Usu-ally they are very fine scratches from cleaning operations thatare not visible when looking through the plastic.Deeperscratches may result from careless cleaning or handling.Whilethese may not be deep enough to affect the structural integrityof the part,their appearance in certain locations may bedistracting to the observer looking through the plastic.Therefore,a procedure to define these scratches is useful.5.Reference MaterialsNOTE1Adjuncts for scratches on plastic are not currently available.However,adjuncts are available for scratches on glass surfaces and a studyhas been done to equate the two(see the Appendix).Refer to F428 forsources of the glass adjuncts.6.Procedure6.1 Place the part in a suitable inspection position.This maybe horizontal on a padded table,vertical against a neutralbackground,or at an angle.The scratched surface shall betoward the observer.The light level shall be a minimum of 80lux.Either natural or artificial light may be used.Place thescratch in the ASTM comparison standard beside and parallelto the scratch to be assessed on the plastic material.Rotate thepart or viewing angle to get the best definition of the scratch.Disregarding the length of the scratch on the plastic materialand on the standard,select and record the highest-numberedstandard scratch that most clearly matches the appearance ofthe scratch on the plastic material.Measure and record thelength of the scratch to the nearest 1 mm(0.04 in.).7.Interpretation7.1 Customer specifications for transparent plastic materialsand parts may detail allowable frequency,location,length,andstandard number for scratches and they may assign maximumscratch limits for critical and noncritical optical viewing areas.8.Report8.1 For each scratch within the scope of the plastic scratchstandard,report its ASTM standard number(for example,ASTM F548-09),length,frequency,and location.9.Precision and Bias39.1 Precision:9.1.1 The repeatability of judging the intensity of a scratchwithin one scratch value,for the same observer,is 92%orbetter.9.1.2 The reproducibility(between observers)of judgingthe intensity of a scratch within one scratch value is 90%orbetter for scratch values 14 and above.The reproducibility ofjudging the intensity of a scratch within two scratch values is92%or better for scratch values below 14.The data reflect thatit is more difficult to judge finer scratches.9.2 BiasThe procedure in this test method has no biasbecause the scratch intensity is defined only in terms of the testmethod.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 onTransparent Enclosures and Materials.Current edition approved Dec.1,2014.Published December 2014.Originallypublished in 1981.Last previous edition approved in 2009 as F548 09.DOI:10.1520/F0548-09R14.2For 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.3A research report is available from ASTM International Headquarters.RequestRR:F07-1007.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 10.Keywords10.1 comparison standard;scratches;transparent plasticAPPENDIX(Nonmandatory Information)X1.COMPARISON OF GLASS AND PLASTIC SCRATCH RATINGSX1.1 A study was performed to determine equivalent rela-tionships between glass and plastic scratch adjuncts.Thisempirically defined relationship can be used if needed when:(1)only glass adjuncts are available to judge the intensity ofscratches in plastic,(2)only plastic adjuncts are