1、Designation: D 5796 03Standard 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 D 5796; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, 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 test method covers the measurement of dry filmthickness (DFT) of coa
3、ting 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 Ap
4、paratus, 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 super
5、sedes 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
6、.NOTE 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 orga
7、nic 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 us
8、ed 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 stat
9、ed 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 an
10、d health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 3794 Guide for Testing Coil Coatings23. Significance and Use3.1 Measurement of dry film thickness of organic coatingsby physically cutting through the film and optic
11、ally 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 sufficie
12、nt.(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,3It is an apparatus consist-ing of either a manual or automated carbide-tipped drill thatraises and lowers the boring
13、tip perpendicular to the surface tobe 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 circular incision in
14、 the paint film at aprecise angle to the surface (see Fig. 1).44.3 Optical Magnification:1This 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 edi
15、tion approved May 10, 2003. Published June 2003. Originallyapproved in 1995. Last previous edition approved in 1999 as D 5796 99.2Annual Book of ASTM Standards, Vol 06.02.3The sole source of supply of the dry film thickness device known to thecommittee at this time is DJH Designs, 2366 Wyecroft Rd.,
16、 Unit D4, Oakville, Ont.,Canada L6L 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, whichyou may attend.4The manufactured angle form
17、ed between the surface of the coating and thesubstrate is 5 42 389 and the resulting crater is circular.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3.1 Method A, Video CameraIt is attached to an illumi-nated microscope and conv
18、eys the image onto a closed-circuittelevision (CCTV) monitor, so that it is an easy matter to lineup the cross-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
19、 to amicroscope with external lighting and conveys the image viasoftware onto a computer monitor. The monitor and 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
20、 a shallow-angle crater of known configuration throughthe coating(s) film into the substrate. The microscope facili-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.5Calibration is a p
21、rocedure that is done during setup andwill require recalibration if changes are made to the micro-scope, boring 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
22、 measuring device.5. Test Specimens5.1 If multiple coats of paint are to be measured, successivecontiguous coats 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 she
23、et) to berepresentative of localized coating thickness and variability.5.3 If test panels are to be laboratory prepared, this shouldbe done using accepted industry practices, in accordance withGuide D 3794.6. Procedure6.1 Select a test panel or choose a site for thicknessmeasurement.6.2 Using an app
24、ropriate surface marker6of contrastingcolor, mark a line on the surface about 25-mm long and 12-mmwide. In most 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 m
25、arker to be absorbed into the coating, up to0.2-mils (5-m) deep. This effect can make it difficult todetermine the 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 a
26、nd lighting shall be agreed upon betweenthe user and customer.6.3 Place the test panel on the borer stage (align the markedline, if required) so that it is positioned under the bit. Clamp thepanel into place.6.4 With a small brush, clean debris from the borer bit, the“depth stop surface,” and the su
27、rface of the test panel. Debrisin these areas will result in a shallower and smaller crater, withconsequently inaccurate results.6.5 Adjust the depth control wheel so that the carbide borerbit just penetrates the metallic substrate, to avoid undue wearon the borer tip. This can only be done by trial
28、 and error dueto substrate thickness variation.6.6 If the boring device is automated, follow the instructionsin 6.6.1; if the boring device is manually operated, follow theinstructions in 6.6.2.6.6.1 Automated Boring DevicePush the button to acti-vate boring device. Do not make a second stroke into
29、the samecrater; do not allow the borer head to penetrate a previouslytested crater.6.6.2 Manual Boring DeviceMove the borer head downin a smooth, slow action to its full travel position, thenimmediately return it to its full rest position. Do not allow theborer head to rest in the “down” position; r
30、agged 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 previouslytested crater.6.7 Place the test panel on the measure stage, and locate thecrater on the monitor by mov
31、ing the panel either with yourhands, or with the two micrometers that control the movementof the stage.6.8 If the viewing method is optical, follow the instructionsin 6.8.1; if the viewing method is software generated, followthe instructions in 6.8.2.6.8.1 Method A, Optical MeasurementAdjust the zoo
32、mlens to 4.5, re-center the crater, and focus. Align the cross-hairin the center of the crater, and using the micrometer adjust-ments that control the vertical and horizontal movement of thestage, move the cross-hair to the inner edge of the crater in thepaint film for which the film thickness needs
33、 to be measured.Zero the micrometer. Then move the microscope stage with themicrometer adjustments so that the cross-hairs are aligned atthe rim of the crater in the paint film. Determine the amount of5The supplier of the standard used to generate the precision statement and usedfor calibration (sil
34、ver-plated, 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
35、 Program, Building 202, Room 204, Gaithersburg, Maryland 20899. Allstandards must be traceable to the National Research Council or the NationalInstitute of Science and Technology.6The marker Sanford Sharpiet used by the committee at this time for this testmethod is Sanford Corp., Bellwood, IL 60104.
36、NOTE 1The drawing is not to scale. It is for illustration purposes only.NOTE 2u = 5 42 389Tan u = A/B = 0.1A = 0.1BFIG. 1 Typical Crater Formed by Boring DeviceD5796032travel from the micrometer and divide this reading by ten (10)to obtain the film thickness of the paint film (see Fig. 2 and Fig.3).
37、6.8.1.1 The reading on the micrometer divided by ten willbe the total mils dry film thickness (DFT). Repeat thisprocedure on the other side of the crater, and average the tworeadings.6.8.1.2 It may be possible to read both the primer and thetopcoat film thicknesses (or any of the constituent layers
38、of amulticoat system) separately. To acquire multicoat film mea-surements, 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.6.8.2 Method B, Software MeasurementAcquire t
39、he im-age by selecting the proper icon on the software menu. Turn themicroscope 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 t
40、he image.Unlike Method A, you are not required to set the zoom at a setlevel for accurate film thickness measurement. Focus themicroscope and adjust the lighting or other video optionsprovided to make the picture more refined. Capture the image.6.8.2.1 Choose the cross-hair icon and center it in the
41、middle of the crater. Mark the points of delineation where thecross-hair and substrate (and other constituent layers) converge(see Fig. 4).6.8.2.2 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
42、build. The number ofpoints chosen to measure determines the number average. 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
43、 for each locationare not needed, report the average thickness of all 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 upo
44、n in-terval of calibration and the date the work was completed.7.1.3 Method 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 w
45、as used.7.1.5 Additional Information to ConsiderReport the iden-tification 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 ap
46、plicationand pertinent physical properties.8. 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 r
47、esults forthe use of the automated boring device (described in 6.6.1) andthe manual boring device (described in 6.6.2).8.1.1 Precision Statement for the Automated Boring Devi-ce: Precision, characterized by repeatability, Sr, r, and repro-ducibility, SR, and R, has been determined for the followingm
48、aterials to be:Materials Average Sr SR r R1006 0.87889 0.05637 0.06987 0.15784 0.195631088 1.01000 0.02698 0.04207 0.07554 0.117791104 0.91333 0.04372 0.05596 0.12241 0.156701105 0.86389 0.02494 0.02755 0.06984 0.07713FIG. 2 Cross-Hair at Bottom (Inner Edge) of CraterFIG. 3 Cross-Hair at Top Edge (R
49、im) of CraterD57960338.1.1.1 RepeatabilityTwo results obtained by the sameoperator using the automated boring device should be consid-ered suspect if they differ by more than 0.11 mils (2.75 m).8.1.1.2 ReproducibilityTwo results obtained by operatorsusing the automated boring device in different laboratoriesshould be considered suspect if they differ by more than 0.14mils (3.50 m).8.1.2 Precision Statement for the Manual Boring Device:Precision, characterized by repeatability, Sr, r, and reproduc-ibility, SR, and R, has been determined for the followingmat
