1、Designation: B926 09Standard Method forPinhole Determination in Aluminum and Aluminum AlloyPlain Foil by Means of a Light Table1This standard is issued under the fixed designation B926; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This method covers the identification and counting ofpinholes, including roll holes, in plain foil usi
3、ng a light table,and inspector with normal 20/20 or corrected 20/20 vision, anda darkened inspection area.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not
4、 considered standard.1.3 This method 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 pract
5、ices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B881 Terminology Relating toAluminum- and Magnesium-Alloy Products3. Terminology3.1 DefinitionsRefer to Terminology B881 for definitionsof product terms used in this specification.
6、3.2 Definitions of Terms Specific to This Standard:3.2.1 calibrationdetermination of the values of the sig-nificant parameter(s) by comparison with a value(s) indicatedby a reference instrument or by a set of reference standards.3.2.2 pinholeany small void in the foil that will permit thetransmissio
7、n of light. Classification criteria for pinholes limitsthese voids to those that are too small in size to be clearlyvisible to the unaided eye (13 visual inspection).3.2.3 roll holethe producers classification of a pinholecaused by an imperfection on any type of roll the foil contactsduring producti
8、on. The distinguishing feature of a roll hole(s)is the repeatability of this void on a regular interval. Thisinterval is directly proportional to the circumference of the rollcausing the void (this interval will also increase proportionallyto subsequent thickness reductions).4. Summary of Method4.1
9、This method contains guidelines for determining thenumber of pinholes present in the area with the highest pinholeconcentration in a sample of foil.4.2 A full width sample is placed on the light table, and thepinholes are counted in a sample of known area (five or moresquare feet).5. Significance an
10、d Use5.1 Foil in thickness of about 0.002 in. (0.05 mm) andheavier is virtually free of pinholes. With decrease in thickness,the number of pinholes may increase.5.2 This method is provided to develop and maintainuniformity in the methods of evaluating pinholes in aluminumfoil. The pinhole data provi
11、des assessments of process capa-bility and quality levels of the foil as well.6. Apparatus6.1 A light table which provides illumination between 1500and 1800 lux light intensity with a smooth and uniforminspection surface on which the foil is examined. The lighttable must be in a black booth or in an
12、 area where the lights areturned off to provide darkness of less than 50 lux. The lighttable should be able to accommodate the widest width of foilto be examined. The usual construction of the light tableconsists of a shallow box painted white on the inside with rowsof fluorescent lights and with a
13、frosted or milk glass coveringto provide uniform light diffusion.6.2 One or more counting frames (grids) that have openingsof one square foot (one square decimeter for SI counts).1This test method is under the jurisdiction of ASTM Committee B07 on LightMetals and Alloys and is the direct responsibil
14、ity of Subcommittee B07.03 onAluminum Alloy Wrought Products.Current edition approved Dec. 1, 2009. Published January 2010. Originallyapproved in 2003. Last previous edition approved in 2003 as B926 03. DOI:10.1520/B0926-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcont
15、act ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
16、 Conshohocken, PA 19428-2959, United States.6.3 Sheet of foil to be tested.6.4 Calibration of the necessary light intensities can beaccomplished using a standard light meter.7. Procedure7.1 Test a full-width representative sample with a minimumof five square feet. Examine the full width of the sheet
17、. The foilgage should be within tolerance.7.2 Place the foil sample on the light table carefully to avoidwrinkling/creasing with the long direction of the bulbs perpen-dicular to the rolling direction of the foil and turn the lights onin the light table and off in the booth or area. Allow areasonabl
18、e time for eyes to adjust to darkened conditions.7.3 If necessary, move the foil on the light table until theentire width has been examined. (Move the foil carefully andas little as possible because moving the sample may createvoids in the sample.)7.4 If a counting frame is used, place it over the a
19、rea andcount the holes. The person should be approximately 18 in.from the sample when counting.7.5 Record the count.8. Report8.1 The report shall include the following:8.1.1 Identification of the roll from which the sample wastaken,8.1.2 The average number of pinholes per square foot ofsample,8.1.3
20、Gage of the foil sample, and8.1.4 Sample lot identification.9. Precision and Bias9.1 PrecisionIt is not practicable to specify the precisionof the procedure in Method B926 for counting pinholesbecause as the gage decreases, their variability and numberincrease.9.2 BiasSince the vision of the inspect
21、or(s) are the mostsignificant aspect of bias in counting pinholes, it is recom-mended that samples of known counts be used routinely toverify if bias exists. Operating outside of the range of lightintensities stated will also cause biased counts.SUMMARY OF CHANGESCommittee B07 has identified the loc
22、ation of selected changes to this standard since the last issue (B926 03)that may impact the use of this standard. (Approved Dec. 1, 2009.)(1) ASTM references B373, B479 and E252 are not referencedin this document and were removed from Section 2.(2) ASTM B881 was added to Section 2 and referenced in
23、Section 3.(3) Foil was removed from Section 3.2, because it is includedin ASTM B881.ASTM 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
24、 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 revised, either reapproved or withdrawn. Your
25、 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 you may attend. If you feel that your comments
26、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 multi
27、ple 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).B926 092
