1、Designation: F 548 09Standard Test Method forIntensity of Scratches on Aerospace Transparent Plastics1This standard is issued under the fixed designation F 548; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. 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 of shallowor superficial scratches on the surface of aerospace transparentplastic
3、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. Re
4、ferenced Documents2.1 ASTM Standards:2F 428 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
5、 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 affe
6、ct the structural integrityof the part, their appearance in certain locations may bedistracting to the observer looking through the plastic. There-fore, a procedure to define these scratches is useful.5. Reference MaterialsNOTE 1Adjuncts for scratches on plastic are not currently available.However,
7、adjuncts are available for scratches on glass surfaces and a studyhas been done to equate the two (see the Appendix). Refer to F 428 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 neutralb
8、ackground, 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
9、 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 re
10、cord 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 noncritic
11、al 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
12、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
13、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
14、 F07 onAerospace and 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 1981. Last previous edition approved in 2003 as F 548 03a1.2For referenced ASTM standards, v
15、isit 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:F07-1007.1Copy
16、right ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.10. Keywords10.1 comparison standard; scratches; transparent plasticAPPENDIX(Nonmandatory Information)X1. COMPARISON OF GLASS AND PLASTIC SCRATCH RATINGSX1.1 A study was performed to determi
17、ne equivalentrelationships 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 available tojudge the intensity of the scratches i
18、n glass, or (3) it is desirableto convert between the glass and 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 th
19、ere be at least fivetrials 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 number of trialsfor each observ
20、er and scratch having a particular scratch ratingwhen compared with either glass or plastic adjunct.NOTE 1The 3 means near (P = 11,G=3)andthe2means near (P = 15,G=8)were not used since they contained multiple trials where the glassrating was either 3 or 8+.FIG. X1.1 Non-Linear Regression Fit of Mean
21、 Scratch Ratings (N = 15)F548092FIG. X1.2 Number of Trials for Each Observer and Scratch (N = 3) Having a Particular Scratch Ratingwhen Compared with Either Glass or Plastic AdjunctF548093ASTM International takes no position respecting the validity of any patent rights asserted in connection with an
22、y 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 rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical
23、 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 additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration a
24、t 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 ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor
25、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).F548094
