1、 FORD LABORATORY TEST METHOD BB 115-01 Date Action Revisions Rev. 1 2014 06 11 Editorial See Summary of Revisions C. Mracna, NA 2013 11 20 Released C. Mracna,NA Controlled document at www.MATS Copyright 2014, Ford Global Technologies, LLC Page 1 of 12 FLAT HEM TEST PROCEDURE FOR ALUMINUM ALLOY SHEET
2、 Application Scope This document covers the operation of a three station die set for testing the flat hemmability of aluminum sheet for closure applications. Significance and Use This procedure shall be used to establish the maximum pre-strain for which an aluminum alloy sheet can be flat hemmed. Fl
3、at hem acceptability is based on the visual inspection and rating of the hem surface appearance. Applicable materials This test applies to aluminum alloy sheet used in closure applications. Applicable Documents ASTM Standard E290-97a Test Methods for the Bend Testing of Material for Ductility ISO 74
4、38 Metallic Materials Bend Test Conflicts In the event of a conflict between the text of this procedure and the references cited herein, the text of this procedure shall take precedence. Definitions Orange Peel - A pebble-grained surface that develops in forming coarse-grained aluminum sheet. Orange
5、 peel roughening is linked with the less constrained deformation of individual grains, with different orientations, at a free surface. It is related to grain size and is not noticeable on fine-grained material, since the individual crystals produce only extremely fine slip lines1. Quality Assurance
6、Requirements Unless otherwise specified, the users of this procedure are responsible for all inspection and the test requirements specified herein, and may use internal testing facilities as long as they meet the requirements of this procedure and any other test agencies acceptable to Ford Motor Com
7、pany. Sampling Samples shall be prepared from a single production lot of alloy. The test report shall contain as a minimum, the following information. (a) Generic and specific product description of each alloy including lot number and date alloy was made. (b) Baseline material properties for each al
8、uminum alloy. (c) Material processing information. (d) Flat hem test ratings for each specimen tested. Replicates At least four (4) sample replicates are required per test condition. FORD LABORATORY TEST METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC Page 2 of 12 Data Reporting All p
9、hysical and mechanical data shall be submitted using the Supplemental Data Reporting Package (SDRP) in Table 1, which is comprised of the form in the reporting section. The SDRP serves as the required reporting format for submitting material data. All material data requested herein shall be manually
10、 recorded onto the reporting forms. Graphs and other requested materials shall be packaged and sent with the SDRP. Apparatus Required Three Station Flat Hemming Die A flat hemming die is described below and shown in Figures 1 and 2. The die set can function within a single action press or load frame
11、. The die set has three discrete forming stations positioned in consecutive order performing each step of a typical press (flat) hem process. An air spring within the die set provides a second action holding the specimen prior to and during the forming operation of each station. The first station cr
12、eates a 900 bend in the outer sheet of the specimen (Fig. 2a, 2b) by flanging over a radius block. The second station closes the outer sheet flange an additional 450 (Fig. 2c, 2d). The third station completes the flat hem of the outer sheet over an inner sheet (Fig. 2e, 2f). Maintenance The die face
13、s of each hemming station should be cleaned with acetone periodically to remove oil and residue from test specimens. All threads, sliding blocks, and bearings must be kept clean and lightly lubricated. FORD LABORATORY TEST METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC Page 3 of 12 (
14、a) (b) Figure 1. (a) Three stations of die set within a manual hydraulic press. (b) Flat hem station lineup within die set. Hydraulic Press Flat Hem Die Set Station 3 Flat Hem Station 2 45 flange Station 1 90 flange FORD LABORATORY TEST METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC
15、Page 4 of 12 (a) Station 1, 90 flanging, Open (b) Station 1, 90 flanging, Closed (c) Station 2, 45 flanging, Open (d) Station 2, 45 flanging, Closed (e) Station 3, Flat hemming, Open (f) Station 3, Flat hemming, Close Figure 2. Open and close positions for each flat hem station. FORD LABORATORY TEST
16、 METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC Page 5 of 12 Test Specimen Dimensions Each hem specimen includes an outer and inner sheet. The outer sheet has dimensions of 73.5 0.5 mm long by 25.5 0.5 mm wide. The inner sheet of the hem test specimen has a length of 57 0.5 mm and a
17、width of 25.5 0.5 mm. Mark the rolling direction on each sheet in the hem. Longitudinal specimens are defined as having the length of the outer sheet parallel to the rolling direction (the bend line is perpendicular to the rolling direction). Transverse specimens are defined as having the length of
18、the outer sheet perpendicular to the rolling direction (the bend line is parallel to the rolling direction). All sheets shall be flat hemmed with the production intent lubricant and coating weight. Dummy Specimen Dimensions Dummy specimens are required for different steps of the hemming process in t
19、he first and/or third stations of the hemming die. The dummies are used to balance / shim the die set during hem press action. The dummy specimen for the third (flat hem) station is to have a thickness equal to twice that of the outer sheet and a length and width equal to that of the inner sheet of
20、the test specimen. The dummy specimen for the first station shall have the dimensions of the inner sheet. Test Specimen Preparation The inner and outer sheet for each specimen may be fabricated with a shear or by electrical discharge machining (EDM). The shear may cause a burr to form on the edge of
21、 the specimen that shall be filed down with medium grit sand paper for a smoother more uniform edge. Cracks observed within one thickness of the edge of the specimen are to be neglected in the bend surface rating analysis for both fabrication methods (shear or EDM). Number of Test Specimens No fewer
22、 than four (4) bend specimens per alloy be tested for each test condition. Flat Hem Procedure Test Conditions: Laboratory ambient conditions are assumed to be 23 2C and 50 5 % Relative Humidity. Exceptions should be noted and reported. 1. Pre-strain outer sheet materials according following procedur
23、e in Appendix B. 2. Trim outer and inner sheet specimens to proper dimensions. 3. Ensure press / die set open height is sufficient for proper loading of specimens. 4. Check setup of bend radius block in station 1 (see Fig. 3). The radius shall be equal to the thickness of the outer sheet of the test
24、 specimen. The block shall be shimmed such that the flanging gap between wipe and bend radius block is equal to outer sheet thickness. 5. Insert the proper dummy specimen into the third station of the die. Align this specimen flush with the back, left corner of the station. FORD LABORATORY TEST METH
25、OD BB 115-01 Copyright 2014, Ford Global Technologies, LLC Page 6 of 12 Figure 3: Outer sheet in first station. 6. Place outer sheet in the first station of the press. Align the sheet flush with the back, right corner of the station. 7. Close press loading die set to a force of 5 +/- 0.25 tons (50 +
26、/- 2.5 kN). 8. Open press. 9. Transfer the outer sheet with 90 flange from the first station to the second station. The sheet should be turned over with flange facing upwards. Align the sheet flush with the back, left corner of the station. 10. Insert the proper dummy specimen into the first station
27、 of the die. Align this specimen flush with the back, left corner of the station. 11. Repeat steps 6 and 7 to form 45 flange shown in Figure 4. Radius Block Outer sheet FORD LABORATORY TEST METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC Page 7 of 12 Figure 4. Outer sheet with 45 flan
28、ge in second station (note dummy specimen in third station) 12. Remove outer sheet (with 45 flange) from the second station and remove dummy specimen from third station. 13. Insert outer sheet (with 45 flange facing up) with nested inner sheet (on top) into the third station. Align both test specime
29、ns flush with the back, left corner of the station. 14. Repeat steps 6 and 7 to form flat hem test specimen as shown in Figure 5. 15. Remove flat hem specimen for post-hem analysis. Figure 5. Outer and inner sheets in 3rd, flat hem station. Outer sheet Dummy Specimen Completed Test Specimen FORD LAB
30、ORATORY TEST METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC Page 8 of 12 Analysis Flat Hem Test Rating Standard The hem surface shall be rated by visual inspection according to the acceptability and severity scales listed below. Any cracks within one thickness of the edge of the spec
31、imen are not considered in the rating process. Acceptable square4 1: No cracking, no to mild orange peel square4 2: No cracking, mild to heavy orange peel. Not acceptable square4 3: Crack initiation lines (i.e. lines of localized thinning or crazing) parallel to the bend line or discontinuous cracks
32、 parallel to bend line. square4 4: Continuous cracks or complete, through-thickness fracture. *Picture examples of each hem rating are available in appendix A. The maximum pre-strain is determined by finding the highest level of pre-strain where all four specimens demonstrate acceptable flat hems ha
33、ving a rating of 1 or 2. Reporting 1. Complete identification of the material(s) tested, including alloy, manufacturer, lot / coil number, production data, gauge, and test date. 2. Complete identification of specimen test condition (i.e. fabrication method, hem orientation, pre-hem procedure, and tr
34、eatments performed on test specimens). 3. The individual hem rating of each specimen is to be recorded noting any unique or out of the ordinary observances. Each specimen should be marked for independent identification for future examination. FORD LABORATORY TEST METHOD BB 115-01 Copyright 2014, For
35、d Global Technologies, LLC Page 9 of 12 Table 1 - Supplemental Data Reporting Package (SDRP) for Pre-Strain Example ID# Manufacturer: External - 2.9 1.0 inches (64 x 25 mm) Internal - 2.25 1.0 inches (57 x 25 mm) Ford Spec No.: Lot/Coil: Alloy: External Gauge: Manuf. Location: Internal Gauge: Recd d
36、ate: Test date: Test Lab: Specimen Orientation Pre-strain (%) Test 1 Test 2 Test 3 Test 4 Max Acceptable Pre-Strain Notes: Rating Guidelines: 1: No cracking, no to mild orange peel 2: No cracking, mild to heavy orange peel. 3: Crack initiation lines (i.e. lines of localized thinning or crazing) para
37、llel to the bend line or any discontinuous cracks parallel to bend line. 4: Continuous cracks or complete, through-thickness fracture. References 1. Altenpohl, D.G., Aluminum: Technology, Application, and Environment, The Aluminum Association and The Minerals, Metals, and Material Society, pp. 438,
38、1998 FORD LABORATORY TEST METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC Page 10 of 12 Appendix A Hem Sample Ratings Figure 6. Rating scale from 4 to 1. Figure 7. Rating 1 vs. rating 2 4 3 3 3 2 1 1 2 FORD LABORATORY TEST METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC
39、 Page 11 of 12 Figure 8. Rating 3 Figure 9. Rating 4 FORD LABORATORY TEST METHOD BB 115-01 Copyright 2014, Ford Global Technologies, LLC Page 12 of 12 Appendix B Method for Applying Nominal Pre-Strain 1. Find the initial length, g1838g2868, to cut the specimen to using formula 1, which is derived fr
40、om the basic strain formula and accounts for added length to be gripped by the tensile machine. g1838g2868 = g1838g30331 + % g1871g1872g1870g1853g1861g1866100%+ 50.8 g1865g1865 (1) For the three station flat hemming die, g1838g3033 is taken to be 2.9 inches (64 mm). % strain is the prescribed pre-st
41、rain defined in the Material Specification. 2. Cut specimen to length g1838g2868 and a width of 1 inch. 3. Use calipers to create a line 1.0 inch (25 mm) from each edge of the initial specimen to guide placement of the tensile machine grips. 4. Secure the specimen in the tensile machine grips. The s
42、pecimen should be centered in the grips and they should reach from the ends of the specimen to the 1.0 inch (25 mm) lines. It is important that the grips do not reach beyond the 1.0 inch (25 mm) lines, as this would cause a lack of pre-strained material in the specimen. However, it is acceptable for
43、 the grips to come slightly short of the line, as this will merely cause an excess of pre-strained material that can be discarded later. 5. Pre-strain sheet within tensile machine using an axial extensometer. 6. Following pre-strain remove the specimen from tensile machine and trim it to 2.9 inches
44、(64 mm) in length. To ensure uniformity among the pre-strained specimens, this is a four step process when using a hand shear. 6.1. Cut off one end of the specimen approximately 0.13 inches (3.2 mm) away from the 1.0 inch (25 mm) line. 6.2. Cut off opposite end directly on 1.0 inch (25 mm) line. 6.3
45、. Use calipers to mark a line exactly 2.9 inches (64 mm) from the end in step 6.2. 6.4. Cut directly on the line created in step 6.3. Note: The reason for the first cut being offset from the line is due to deformation in the specimen causing alignment problems while attempting to make right angle cuts. Summary of Revisions 2014 06 11 Updated Figure 6 to correct typo. Cropped and clarified a portion of Figure 9.
