1、Designation: F 428 09Standard Test Method forIntensity of Scratches on Aerospace Glass Enclosures1This standard is issued under the fixed designation F 428; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 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 covers the visual inspection ofscratches on the glass surface of aerospace transparent enclo-sures.1.2 The values s
3、tated 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, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the re
4、sponsibility 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 i
5、s 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
6、 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
7、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 F 428-3 and the heaviest asASTM F 428-8.36. Procedur
8、e6.1 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 natur
9、al 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
10、. 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
11、surfacedtransparent enclosures may detail allowable frequency, loca-tion, length, and ASTM standard scratch number for scratchesand they may assign maximum scratch limits for critical andnoncritical optical viewing areas.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace a
12、nd Aircraft and is the direct responsibility of Subcommittee F07.08 onTransparent Enclosures and Materials.Current edition approved May 15, 2009. Published June 2009. Originallypublished in 1977. Last previous edition approved in 2003 as F 428 03a.2The sole source of supply of the Glass Scratch Visu
13、al 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 o
14、f the responsible technical committee,1which you may attend.3Originally an adjunct that contained seven scratches was used. The finestscratch (ASTM F 428-2) was determined to be too difficult to use and manufacture.Subsequently, it has been discontinued. Continued use of the older, seven-piece setis
15、 acceptable.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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. Pr
16、ecision and Bias49.1 Precision: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 proc
17、edure in this test method has no biasbecause the scratch intensity is defined only in terms of the testmethod.10. Keywords10.1 glass scratches; scratches; windscreen quality; wind-screen scratchesAPPENDIX(Nonmandatory Information)X1. COMPARISON OF GLASS AND PLASTIC SCRATCH RATINGSX1.1 A study was pe
18、rformed to determine equivalentrelationships between glass and plastic scratch adjuncts. Thisempirically derived 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 available tojudge the intensity
19、of scratches in glass, or (3) it is desirable toconvert between the glass and plastic scratch scales.X1.2 Five trained observers rated eight glass and eightplastic test scratches. Each scratch was rated using both glassand plastic adjuncts three times. The 96 trials for each observerwere randomized
20、with the constraint that there be at least fivetrails between replications of the same scratch and either glassor plastic adjunct.X1.3 Fig. X1.1 contains the estimated relationship betweenthe glass (G) and plastic (P) scratch ratings and between theplastic and glass ratings. Fig. X1.2 shows the numb
21、er of trialsfor each observer and scratch having a particular scratch ratingwhen compared with either glass or plastic adjunct.4A research report is available from ASTM International Headquarters. RequestRR:F07-1008.F428092NOTEThe 3 means near (P = 11,G=3)andthe2means near (P = 15,G=8)were not used
22、since they contained multiple trials where the glass ratingwas either 3 or 8+.FIG. X1.1 Non-Linear Regression Fit of Mean Scratch Ratings (N = 15)F428093FIG. X1.2 Number of Trials for Each Observer and Scratch (N = 3) Having a Particular Scratch Ratingwhen Compared with Either Glass or Plastic Adjun
23、ctF428094ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such ri
24、ghts, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additiona
25、l standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the AST
26、M Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F428095
