1、Designation: F 428 03aStandard 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 (e) 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 This stand
3、ard 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 responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicabi
4、lity of regulatory limitations prior to use.2. Referenced Documents2.1 Other Standards:Glass Scratch Visual Comparison Standard23. 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 relati
5、ve 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 enclosure.Therefore, a
6、 procedure to define scratches is useful. A visualstandard is used because it is not practical to measure thedimensions of the fine scratches in the scope of this testmethod.5. Reference Materials5.1 Glass Scratch Visual Comparison Standard consists of aset of six hermetically sealed glass plates 38
7、 mm (1.5 in.)square with scratches of graded intensity on the inside surface.The lightest scratch is identified as ASTM F 428-3 and theheaviest as ASTM F 428-8.36. Procedure6.1 Place the part in a suitable inspection position. This maybe horizontal on a padded table, vertical against a neutral todar
8、k 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.
9、 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
10、 the appearanceof the scratch on the part. Measure and record the length of thescratch to the nearest 1 mm (or 0.05 in.).7. Interpretation7.1 Customer specifications for aerospace glass surfacedtransparent enclosures may detail allowable frequency, loca-tion, length, and standard number for scratche
11、s and they mayassign maximum scratch limits for critical and noncriticaloptical viewing areas.8. Report8.1 For each scratch within the scope of the glass scratchstandard, report its standard number, length, frequency, andlocation.9. Precision and Bias49.1 Precision:9.1.1 The repeatability of judging
12、 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.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and
13、 Aircraft and is the direct responsibility of Subcommittee F07.08 onTransparent Enclosures and Materials.Current edition approved Oct. 1, 2003. Published November 2003. Originallypublished in 1977. Last previous edition approved in 2003 as F 428 03.2The sole source of supply of the Glass Scratch Vis
14、ual 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
15、of the responsible technical committee,1which you may attend.3Originally an adjunct that contained seven scratches. The finest scratch (ASTMF 4282) was determined to be too difficult to use and manufacture. Subsequently,it has been discontinued. Continued use of the older, seven-piece set is accepta
16、ble.4A research report is available from ASTM International Headquarters. RequestRR:F07-1008.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.9.2 BiasThe procedure in this test method has no biasbecause the scratch intensity is define
17、d 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 performed to determine equivalentrelationships between glass and plastic scrat
18、ch 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 of scratches in glass, or (3) it is desirable toconvert between the glass an
19、d plastic scales.X1.2 Five trained observers rated eight glass and eightplastic scratches. Each scratch was rated using both glass andplastic adjuncts three times. The 96 trials for each observerwere randomized with the constraint that there be at least fivetrails between replications of the same sc
20、ratch 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 number of trialsfor each observer and scratch having a particular scratch ratingwhen compared
21、 with either glass or plastic adjunct.NOTEThe 3 means near (P = 11,G=3)andthe2means near (P = 15,G=8)were not used 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)F 428 03a2FIG. X1.2 Number of Trials fo
22、r Each Observer and Scratch (N = 3) Having a Particular Scratch Ratingwhen Compared with Either Glass or Plastic AdjunctF 428 03a3ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard a
23、re expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, 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
24、 revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which y
25、ou may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM 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).F 428 03a4
