ASTM_F_428_-_09_2014.pdf

Designation:F42809(Reapproved 2014)Standard Test Method forIntensity of Scratches on Aerospace Glass Enclosures1This standard is issued under the fixed designation F428;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 ofscratches on the glass surface of aerospace transparent enclo-sures.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard may involve hazardous materials,operations,and equipment.This standard does not purport toaddress all of the safety concerns,if any,associated with itsuse.It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 Other Standards:2Glass Scratch Visual Comparison Standard3.Summary of Test Method3.1 A visual comparison is made between a set of gradedscratch standards and the scratch on the glass aerospacetransparency to determine the relative intensity of the scratch.4.Significance and Use4.1 Scratches exist on all glass surfaces.Often there are veryfine scratches from cleaning operations that are not visiblewhen looking through the glass.Visible scratches may bedistracting to the observer looking through the transparency.Therefore,a procedure to define the severity scratches isuseful.A visual standard is used because it is not practical tomeasure the dimensions of the fine scratches in the scope ofthis test method.5.Reference Materials5.1 Glass Scratch Visual Comparison Standard consists of aset of six hermetically sealed glass plates 38 mm square withscratches of graded intensity on the inside surface.The lightestscratch is identified as ASTM F428-3 and the heaviest asASTM F428-8.36.Procedure6.1 Place the part in a suitable inspection position.This maybe horizontal on a padded table,vertical against a neutral todark background,or at an angle simulating the installedposition.The scratched surface shall be toward the observer.The light level shall be a minimum of 80 lux.Either natural orartificial light may be used.If possible,move the light until thescratch has the highest contrast against the background.Placethe scratch in the visual comparison standard beside andparallel to the scratch in question.Rotate the part or viewingangle to get the best definition of the scratch.Disregarding thelength of the scratch on the part and on the standard,select andrecord the standard that most closely matches the appearanceof the scratch on the part.Measure and record the length of thescratch to the nearest 1 mm.7.Interpretation7.1 Customer specifications for aerospace glass surfacedtransparent enclosures may detail allowable frequency,location,length,and ASTM standard scratch number forscratches and they may assign maximum scratch limits forcritical and noncritical optical viewing areas.8.Report8.1 For each scratch within the scope of the glass scratchstandard,report its ASTM standard number(for example,ASTM F428-5),length,frequency,and location.9.Precision and Bias49.1 Precision: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 1977.Last previous edition approved in 2009 as F428 09.DOI:10.1520/F0428-09R14.2The sole source of supply of the Glass Scratch Visual Comparison Standardknown to the committee at this time is Davidson Optronics,Inc.,2223 RamonaBlvd.,West Covina,CA 91790.If you are aware of alternative suppliers,pleaseprovide this information to ASTM International Headquarters.Your comments willreceive careful consideration at a meeting of the responsible technical committee,1which you may attend.3Originally an adjunct that contained seven scratches was used.The finestscratch(ASTM F428-2)was determined to be too difficult to use and manufacture.Subsequently,it has been discontinued.Continued use of the older,seven-piece setis acceptable.4A research report is available from ASTM International Headquarters.RequestRR:F07-1008.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 9.1.1 The repeatability of judging the intensity of a scratchwithin one scratch value,for the same observer,is 90%orbetter.9.1.2 The reproducibility(between observers)of judgingthe intensity of a scratch within two scratch values is 87%orbetter.9.2 BiasThe procedure in this test method has no biasbecause the scratch intensity is defined only in terms of the testmethod.10.Keywords10.1 glass scratches;scratches;windscr