1、 FORD LABORATORY TEST METHOD BQ 010-01 Date Action Revisions 2000 11 09 Ed itorial no technical change A. Cockman 1992 08 05 Printed copies are uncontrolled Page 1 of 7 Copyright 2000, Ford Global Technologies, Inc. TEST PROCEDURES FOR ANODIZED ALUMINUM FILM THICKNESS MEASUREMENT Application The fol
2、lowing procedures describe the use of the Zeiss light section microscope for the nondestructive measurement of anodized aluminum film thickness. This light section micr oscope has been specially designed for testing and measuring the surface quality of production parts. The operating procedures in t
3、he instrument manual are limited to this application only. However, this instrument, having its design based upon the light section principle, has been found to be adaptable to the measurement of thin film thicknesses of any transparent coating over both magnetic and nonmagnetic surfaces. (Reference
4、: Special Report MDJA 8112.4 - 5 “A Nondestructive Method for Measuring the Thic kness of Thin Transparent Coatings over Metallic and Nonmetallic Surfaces“, by T. M. Mansour, Process Development Department, Manufacturing Engineering & Development Office, Manufacturing Staff, March, 1962 - Job Nos. 1
5、 - H - 64 and 2 - A - 38.) Apparatus Required Zeiss Light Section Microscope The basic light section microscope unit, shown in the attached photograph (Figure 1) consists of the following major components: 1. A microscope with built - in illumination device, built -in measuring eyepiece and two pai
6、rs of objectives for 200X and 400X total magnifications respectively. 2. A stand with stage plate. 3. Three 6 - volt, 5 - watt incandescent lamps in centering mounts (two as spares). 4. A power supply unit for 110 - volt, 60 cycle operation. 5. A dust protec tion sheath. 6. Instrument manual. Source
7、: Carl Zeiss, Inc. or Morgan Instrument Inc. 485 Fifth Ave. 1025 E. Maple Rd. New York, NY Birmingham, MI 48011 (313) 646 - 5170 FORD LABORATORY TEST METHOD BQ 010-01 Page 2 of 7 Copyright 2000, Ford Global Technologies, Inc. Note: The ordering code number for the above mentioned basic equipment is
8、60/49/99. 7. A mechanical stage with V -bearings is available as a supplementary accessory (Code No. 60/49/96). This was found to be quite helpful in positioning relatively small test samples. Flat Glass Reference Surface A flat glass reference surfac e is required for proper alignment of the slit i
9、mage. This is recommended to be an approximately 50 x 50 mm piece of plate glass of 0.8 mm minimum thickness. Sample Holder The sample holder is recommended to be a clamping device (or equivalent) compatibl e with the size and shape of the samples to be tested, which will facilitate positioning the
10、test sample so that the test area is very nearly normal to the axis of the microscope. The test area is approximately 2.0 mm long and of negligible width. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/ - 2 C and
11、 50 +/ - 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless o therwise specified. Procedure A. Instrument Set-Up 1. Place the instrument on a flat and relatively vibration - free surface. 2. Insert the instrument cable into the plug of the power
12、 supply unit and connect the latter to a 110 volt, 60 cycle power line . 3. Switch the power supply unit on by setting the knob provided to any mark between 1 and 8 on the graduated disc. This setting may later be changed to obtain a desired level of illumination. B. Initial Focus and Alignment 1. F
13、ocus the cross lines, v isible through the eyepiece, as outlined in the instrument manual (supplied by the manufacturer). 2. Place the flat glass reference surface on the stage plate. The surfaces of this glass piece must be thoroughly clean - free of fingerprints, grease film, etc. 3. Looking into
14、the eyepiece, lower the microscope body by turning the vertical drive knob slowly, to obtain a well - focused light band. FORD LABORATORY TEST METHOD BQ 010-01 Page 3 of 7 Copyright 2000, Ford Global Technologies, Inc. 4. This light band should be parallel to the horizontal portion of the cross - li
15、nes. If it is not parallel, it should be aligned accordingly by means of the knob provided, as outlined in the instrument manual. Once this light band has been properly aligned, the aligning knob should not be touched in the course of instrument operation. 5. By means of the vertical drive knob, ele
16、vate the microscope body to a safe clearing distance between objectives and stage plate. 6. Remove the glass reference surface from the stage plate. C. Selecting the Objectives 1. Select the 400X total magnification pair of objectives. A t this level of magnification, each division on the measuring
17、drum is equivalent to micron. Anodic film thickness up to 0.8 mils (20 microns) are easily measured at this magnification level. For measurements of thicker films, the 200X total magnificati on pair of objectives are used, in which case each division on the measuring drum will be equivalent to 1 mic
18、ron. D. Coating Thickness Measurement 1. Place the test sample directly below the microscope objectives. A relatively small sample may be placed on the stage plate. For measurements on larger samples, the microscope body can be swiveled through 180 degrees about its vertical axis. 2. Looking into th
19、e eyepiece, turn the focusing drive knob slowly, advancing the microscope toward the test area, un til a focused three - lined image of the light band appears in the field of view. In some cases a four -lined image will appear in the field of view, particularly in the case of thicker coatings. Adjus
20、t the power supply unit knob to obtain the desired level of illumination. Note: This multiple - lined image will consist of three (or four) essentially parallel and equidistant bands: The first (from the bottom) adopting the profile of the top surface of the coating, and the second band adopting the
21、 surface p rofile of the coated surface. 3. In the case of a flat test surface, the light bands should be essentially parallel to the horizontal cross -line, if the test area is properly positioned (normal to the axis of the microscope). See Figure 2. If these are not parallel, the test sample posit
22、ion should be altered accordingly. Care must be taken when adjusting the sample position, to avoid bumping the microscope objectives. 4. In the case of a curved test surface, these light bands will, of course, appear cu rved accordingly. Here the test area needs to be positioned so that the center o
23、f curvature lies on the axis of the microscope (or an extension of it, depending on whether this curvature is concave or convex). This position is easily achieved by adjustin g the sample position until a well - defined image similar to that in Figure 3 (or an inverted image of it, depending on the
24、type of curvature) is visible in the field of view. 5. Disregarding the vertical portion of the cross - lines visible in he eyepiece, set the horizontal portion of the third band from the bottom and record the measuring drum setting. See first position of horizontal cross - line in Figures 2 and 3.
25、FORD LABORATORY TEST METHOD BQ 010-01 Page 4 of 7 Copyright 2000, Ford Global Technologies, Inc. 6. Turn the micrometer measuring drum to move the horizontal cross - line to the center of the first band (from the bottom), (second position of horizontal cross - line Figures 1 and 2), and record this
26、measuring drum setting. 7. Subtract the first reading from the second to obtain the instrument reading in 1/2 microns. 8. Refer to the attached conversion chart to obtain the film thickness in mils from this reading. This chart is especially prepared for direct conversion of the 1/2 micron reading b
27、etween the first and third bands, for anodized aluminum, into mils of film thickness. The convers ion factor here (which includes the correction factor and the microns - to - mils ratio) is: Number of divisions times 0.209. (Reference: Special Report MDJA 8112.4 - 5, referred to in the introduction
28、section.) Routine Care and Maintenance 1. Keep all expo sed parts of the instrument clean and covered with the supplied protective sheath when not in use. 2. Avoid sudden jarring or bumping of the instrument. 3. To prolong the life of the illumination lamp, do not set the power supply unit higher th
29、an the #8 mark on the graduated disc and turn off when not in use. Refer to the instrument manual for lamp replacements. 4. The instrument can, in some cases, be operated with room overhead lights on, however, the distinctness of image will be appreciably enhanced when viewed in a dark surrounding.
30、Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD BQ 010-01 Page 5 of 7 Copyright 2000, Ford Global Technologies, Inc. TEST PROCEDU
31、RES FOR ANODIZED ALUMINUM FILM THICKNESS MEASUREMENT Figure 1 FORD LABORATORY TEST METHOD BQ 010-01 Page 6 of 7 Copyright 2000, Ford Global Technologies, Inc. TEST PROCEDURES FOR ANODIZED ALUMINUM FILM THICKNESS MEASUREMENT Typical Image from Flat Test Surface Figure 2 Typical Image from Curved Test Surface Figure 3 FORD LABORATORY TEST METHOD BQ 010-01 Page 7 of 7 Copyright 2000, Ford Global Technologies, Inc. TEST PROCEDURES FOR ANODIZED ALUMINUM FILM THICKNESS MEASUREMENT
