1、Designation: D5796 10Standard Test Method forMeasurement of Dry Film Thickness of Thin-Film Coil-Coated Systems by Destructive Means Using a BoringDevice1This standard is issued under the fixed designation D5796; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the case of revision, 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. Scope1.1 This test method covers the measurement of dry filmthickness (DFT) of coatin
3、g films by microscopic observation ofa precision-cut, shallow-angle crater bored into the coatingfilm. This crater reveals cross sectional layers appearing asrings, whose width is proportional to the depth of the coatinglayer(s) and allows for direct calculation of dry film thickness.1.1.1 The Appar
4、atus, Procedure, and Precision and Biasdiscussions include Method A and Method B. Method Ainvolves the use of an optical measurement apparatus which isno longer commercially available, but remains a valid methodof dry film measurement. Method B is a software drivenmeasurement procedure that supersed
5、es Method A.1.2 The substrate may be any rigid, metallic material, suchas cold-rolled steel, hot-dipped galvanized steel, aluminum,etc. The substrate must be planar with the exception ofsubstrates exhibiting “coil set,” which may be held level by theuse of the clamping tool on the drilling device.NO
6、TE 1Variations in the surface profile of the substrate may result inmisrepresentative organic coating thickness readings. This condition mayexist over substrates such as hot-dipped, coated steel sheet. This is true ofall “precision cut” methods that are used to determine dry film thicknessof organic
7、 coatings. This is why several measurements across the stripmay be useful if substrate surface profile is suspect.1.3 The range of thickness measurement is 0 to 3.5 mils (0to 89 m).NOTE 2For DFT measurements of films greater than 3.5 mils (89m),but less than 63 mils (1600 m), a 45 borer may be used
8、in accordancewith this test method, with the exception of 6.8, where the micrometerreading would provide a direct read-out, and division by ten would beunnecessary per 4.3.1 Method A.1.4 Measurements may be made on coil-coated sheet, cer-tain formed products, or on test panels.1.5 The values stated
9、in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 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 h
10、ealth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D3794 Guide for Testing Coil Coatings33. Significance and Use3.1 Measurement of dry film thickness of organic coatingsby physically cutting through the film and opticall
11、y observingand measuring the thickness offers the advantage of directmeasurement as compared with nondestructive means.3.2 Constituent coating layers of an overall thickness of acoating system can usually be measured individually by thistest method, provide adhesion between each layer is sufficient.
12、(However, this can be difficult in cases where the primer,topcoat, or multiple coating layers have the same, or verysimilar, appearance.)4. Apparatus4.1 Dry Film Thickness Device,4It is an apparatus consist-ing of either a manual or automated carbide-tipped drill thatraises and lowers the boring tip
13、 perpendicular to the surface to1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.53 on Coil Coated Metal.Current edition approved Dec. 1, 2010. Published December 2010. Orig
14、inallyapproved in 1995. Last previous edition approved in 2010 as D5796 03 (2010).DOI: 10.1520/D5796-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standard
15、s Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4The sole source of supply of the dry film thickness device known to thecommittee at this time is DJH Designs, 2366 Wyecroft Rd., Unit D4, Oakville, Ont.,Canada L
16、6L 6M1. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box
17、C700, West Conshohocken, PA 19428-2959, United States.be tested, a cleaning brush, a marking device (optional), and avideo imaging system, which is attached to a microscope thatviews the crater formed by the boring device.4.2 Carbide Borer Bit, The configuration is designed toprovide a very smooth c
18、ircular incision in the paint film at aprecise angle to the surface (see Fig. 1).54.3 Optical Magnification:4.3.1 Method A, Video CameraIt is attached to an illumi-nated microscope and conveys the image onto a closed-circuittelevision (CCTV) monitor, so that it is an easy matter to lineup the cross-
19、hair on the enlarged image. This very effectivelyminimizes error or lack of consistency on the part of theoperator in lining up the cross-hair.4.3.2 Method B, Computer MonitorIt is attached to amicroscope with external lighting and conveys the image viasoftware onto a computer monitor. The monitor a
20、nd softwareenlarge the image for viewing and measuring, while thecomputer retains the picture as an image file, if the user desires.4.4 MicroscopeThe measurement is performed by firstboring a shallow-angle crater of known configuration throughthe coating(s) film into the substrate. The microscope fa
21、cili-tates viewing and measuring the crater.4.5 The instrument is calibrated by taking measurements ona standard, which is traceable to a national standards institu-tion.6Calibration is a procedure that is done during setup andwill require recalibration if changes are made to the micro-scope, boring
22、 device, or the camera system. Calibration veri-fication should be done at intervals agreed upon between theuser and the consumer, but no less often than indicated by themanufacturer of the measuring device.5. Test Specimens5.1 If multiple coats of paint are to be measured, successivecontiguous coat
23、s should be of contrasting colors to aid sharpdiscrimination of interfaces (see 3.2).5.2 Generally, test specimens shall be prepared (as testpanels) or chosen (as sites on a coil-coated sheet) to berepresentative of localized coating thickness and variability.5.3 If test panels are to be laboratory
24、prepared, this shouldbe done using accepted industry practices, in accordance withGuide D3794.6. Procedure6.1 Select a test panel or choose a site for thicknessmeasurement.6.2 Using an appropriate surface marker7of contrastingcolor, mark a line on the surface about 25-mm long and 12-mmwide. In most
25、cases, the use of a marker is not necessary, butfor certain colors, usually whites, its use may be desirable.Depending upon the coating and the type of marker used, it ispossible for the marker to be absorbed into the coating, up to0.2-mils (5-m) deep. This effect can make it difficult todetermine t
26、he position of the top edge of the crater. Externalfluorescent lighting may be positioned to enhance the imageand eliminate the need for a marker. The use of a marker,lighting, or marker and lighting shall be agreed upon betweenthe user and customer.6.3 Select the appropriate borer bit. A typical bi
27、t used forcoil coatings has a depth range of 0 to 2 mils, but others areavailable. The bit type and depth range shall be agreed uponbetween the user and customer.6.4 Place the test panel on the borer stage (align the markedline, if required) so that it is positioned under the bit. Clamp thepanel int
28、o place.6.5 With a small brush, clean debris from the borer bit, the“depth stop surface,” and the surface of the test panel. Debrisin these areas will result in a shallower and smaller crater, withconsequently inaccurate results.6.6 Adjust the depth control wheel so that the carbide borerbit just pe
29、netrates the metallic substrate, to avoid undue wearon the borer tip. This can only be done by trial and error dueto substrate thickness variation.6.7 If the boring device is automated, follow the instructionsin 6.7.1; if the boring device is manually operated, follow theinstructions in 6.7.2.6.7.1
30、Automated Boring DevicePush the button to acti-vate boring device. Do not make a second stroke into the samecrater; do not allow the borer head to penetrate a previouslytested crater.6.7.2 Manual Boring DeviceMove the borer head downin a smooth, slow action to its full travel position, thenimmediate
31、ly return it to its full rest position. Do not allow theborer head to rest in the “down” position; ragged edges orsmeared coating may result, rendering accurate film measure-ment more difficult. Do not make a second stroke into the samecrater; do not allow the borer head to penetrate a previouslytes
32、ted crater.6.8 Place the test panel on the measure stage, and locate thecrater on the monitor by moving the panel either with yourhands, or with the two micrometers that control the movementof the stage.6.9 If the viewing method is optical, follow the instructionsin 6.9.1; if the viewing method is s
33、oftware generated, followthe instructions in 6.9.2.5The manufactured angle formed between the surface of the coating and thesubstrate is 5 42 ft 38 in. and the resulting crater is circular.6The supplier of the standard used to generate the precision statement and usedfor calibration (silver-plated,
34、copper substrate) is DJH Designs. The DJH Designsstandard is traceable to the NRC, Montreal Road Building M-36, Ottawa, Canada,K1A 0R6. An additional acceptable standard for calibration (copper and chromiumcoating on steel, SRM 1357) may be obtained from NIST, Standard ReferenceMaterials Program, Bu
35、ilding 202, Room 204, Gaithersburg, Maryland 20899. Allstandards must be traceable to the National Research Council or the NationalInstitute of Science and Technology.7The marker Sanford Sharpie, a registered trademark of Sanford, used by thecommittee at this time for this test method is Sanford Cor
36、p., Bellwood, IL 60104.NOTE 1The drawing is not to scale. It is for illustration purposes only.NOTE 2u =542ft38in.Tan u = A/B = 0.1A = 0.1BFIG. 1 Typical Crater Formed by Boring DeviceD5796 1026.9.1 Method A, Optical MeasurementAdjust the zoomlens to the maximum allowable zoom to fill the screen wit
37、h theimage of the crater. Re-center the crater, and focus. Adjust thelightning to give maximum visual contrast between coatingsand coating/substrate. Align the cross-hair in the center of thecrater, and using the micrometer adjustments that control thevertical and horizontal movement of the stage, m
38、ove thecross-hair to the inner edge of the crater in the paint film forwhich the film thickness needs to be measured. Carefully alignthe outer edge of the corsshair with the edge of the coating.Zero the micrometer. Then move the microscope stage with themicrometer adjustments so that the outer edge
39、of the cross-hairs are aligned at the rim of the crater in the paint film.Determine the amount of travel from the micrometer anddivide this reading by ten (10) to obtain the film thickness ofthe paint film (see Fig. 2 and Fig. 3).6.9.1.1 The reading on the micrometer divided by ten willbe the total
40、mils dry film thickness (DFT). Repeat thisprocedure on the other side of the crater, and average the tworeadings.6.9.1.2 It may be possible to read both the primer and thetopcoat film thicknesses (or any of the constituent layers of amulticoat system) separately. To acquire multicoat film mea-sureme
41、nts, each coating layer must exhibit good adhesion,which appears as a smooth circular cut without ragged edges ordebris so a definite, visible delineation of the film layers ispossible.6.9.2 Method B, Software MeasurementAcquire the im-age by selecting the proper icon on the software menu. Turn them
42、icroscope lens so it zooms out and center the image of thecrater on the screen by turning the micrometers attached to thestage. Zoom in again to fill the screen with the crater whileadjusting the micrometers to maintain a fix on the image.Unlike Method A, you are not required to set the zoom at a se
43、tlevel for accurate film thickness measurement. Focus themicroscope and adjust the lighting or other video optionsprovided to make the picture more refined. Capture the image.6.9.2.1 Choose the cross-hair icon and center it in themiddle of the crater. Mark the points of delineation where thecross-ha
44、ir and substrate (and other constituent layers) converge(see Fig. 4).6.9.2.2 The average readings with respect to the placementof the identified points on the cross-hairs will appear on thescreen along with the total average film build. The number ofpoints chosen to measure determines the number ave
45、rage. Ifthe user desires, the software will show each reading separatelyon the screen.7. Report7.1 Report the following information:7.1.1 Results of a Thickness DeterminationIf more thanone measurement is made and specific results for each locationare not needed, report the average thickness of all
46、readings andthe number of readings taken. It is not necessary to drill morethan one crater, but it is suggested that the maximum numberof readings be taken in each crater measured.7.1.2 Interval of CalibrationReport the agreed upon in-terval of calibration and the date the work was completed.7.1.3 M
47、ethod Used for TestingNote if Method A orMethod B use used to perform the testing. Report the devicemodel used to perform the testing.7.1.4 Choice of Marker or LightingReport the type ofmarker used, if any, and what light source was used.7.1.5 Additional Information to ConsiderReport the iden-tifica
48、tion of the coating(s) or sample(s) examined. Considerincluding a physically descriptive form of the test substrate,(for example, lab applied hot-dipped steel test panel, lineapplied cold rolled steel sample), the parameters of applicationand pertinent physical properties.FIG. 2 Cross-Hair at Bottom
49、 (Inner Edge) of CraterFIG. 3 Cross-Hair at Top Edge (Rim) of CraterD5796 1038. Precision and Bias8.1 PrecisionStatistical analysis of an intralaboratory (re-peatability) and interlaboratory (reproducibility) round robinstudy (conducted using silver-on-copper standards, identifiedas Materials 1006, 1088, and 1105) yielded separate results forthe use of the automated boring device (described in 6.7.1) andthe manual boring device (described in 6.7.2).8.1.1 Precision Statement for the Automated Boring Devi-ce: Precision, characterized by repeatability, Sr, r,
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