1、Designation: B 926 03Standard Method forPinhole Determination in Aluminum and Aluminum AlloyPlain Foil by Means of a Light Table1This standard is issued under the fixed designation B 926; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the year of last revision. 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 method covers the identification and counting ofpinholes, including roll holes, in plain foil u
3、sing a light table,and inspector with normal 20/20 or corrected 20/20 vision, anda darkened inspection area.1.2 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 resp
4、onsibility 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 ASTM Standards:B 373 Specification for Aluminum Foil for Capacitors2B 479 Specification for Annealed Aluminum
5、 andAluminum-Alloy Foil for Flexible Barrier, Food Contact,and Other Applications2E 252 Test Method for Thickness of Thin Foil and Film byWeighing23. Terminology3.1 Definitions:3.1.1 calibrationdetermination of the values of the sig-nificant parameter(s) by comparison with a value(s) indicatedby a r
6、eference instrument or by a set of reference standards.3.1.2 foila rolled metallic product rectangular in cross-section and of a thickness less than 0.006 in. (0.15 mm). Thismethod was developed based on aluminum foil, but could beapplied to other types of metallic foil as well.3.1.3 pinholeany smal
7、l void in the foil that will permit thetransmission 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).3.1.4 roll holethe producers classification of a pinholecaused by an imperfection on
8、 any type of roll the foil contactsduring production. 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 subsequ
9、ent thickness reductions).4. Summary of Method4.1 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
10、 area (five or moresquare feet).5. Significance and 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 evaluatin
11、g pinholes in aluminumfoil. The pinhole data provides 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
12、. The lighttable must be in a black booth or in an 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
13、 inside with rowsof fluorescent lights and with a 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).6.3 Sheet of foil to be tested.6.4 Calibration of the necessary light i
14、ntensities can beaccomplished using a standard light meter.1This test method is under the jurisdiction of ASTM Committee B07 on LightMetals and Alloys and is the direct responsibility of Subcommittee B07.03 onAluminum Alloy Wrought Products.Current edition approved April 10, 2003. Published August 2
15、003.2Annual Book of ASTM Standards, Vol 02.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Procedure7.1 Test a full-width representative sample with a minimumof five square feet. Examine the full width of the sheet. The foilgag
16、e 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 areasonable time for ey
17、es 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 area andcount
18、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 Gage of the f
19、oil sample, and8.1.4 Sample lot identification.9. Precision and Bias9.1 PrecisionIt is not practicable to specify the precisionof the procedure in Method B 926 for counting pinholesbecause as the gage decreases, their variability and numberincrease.9.2 BiasSince the vision of the inspector(s) are th
20、e mostsignificant aspect of bias in counting pinholes, it is recom-mended that samples of know counts be used routinely toverify if bias exists. Operating outside of the range of lightintensities stated will also cause biased counts.ASTM International takes no position respecting the validity of any
21、 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 rights, are entirely their own responsibility.This standard is subject to revi
22、sion 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 additional standardsand should be addressed to ASTM International Headquarters. Your
23、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 ASTM Committee on Standards, at the address shown below.This standard is copyri
24、ghted 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).B926032
