1、 FORD LABORATORY TEST METHOD BB 117-01 Date Action Revisions Rev. 0 2014 04 01 Released E. Hetrick / W. Moision, NA Controlled document at www.MATS Copyright 2014, Ford Global Technologies, Inc. Page 1 of 8 RESISTANCE SPOT WELDING ACCEPTANCE TEST FOR ALUMINUM Application The procedure outlined herei
2、n is a standard welding acceptance test for a given aluminum alloy + pretreatment + lubricant + heat treatment system of a specific gauge from a specific supplier. Upon passing this procedure, the aluminum alloy system (gauge, pretreatment, lubricant, and heat treatment-specific) is recognized as re
3、sistance weldable by Ford Motor Company. Essentially, it is a procedure to approve the capability of a supplier or Company activity to obtain a spot weldable surface. This procedure shall constitute a method by which such a supplier or Company activity may become an approved supplier of spot weldabl
4、e aluminum and as a quality control procedure for checking consistency of weldability. 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. Equipment Required Res
5、istance Spot Welder This test shall be conducted using a Medium Frequency Direct Current (MFDC) inverter combined with servo-actuated force including force feedback and servo-inverter synchronization. The weld gun shall be capable of electrode forces up to 10 kN. It shall be equipped with a Ford app
6、roved aluminum resistance welding control and gun. The weld controller shall have current capacities to meet the requirements of the range of material to be tested at a minimum rate of 10 welds per minute. The welder must be equipped with electrode holders capable of sufficient water flow capacity s
7、o that a minimum of 2.0 gal/min will flow through each electrode holder with a 20 psi pressure differential. In addition, other cooling circuits (e.g. transformer, secondary conductors, and control panel) must meet the minimum manufacturer-specified flow rates and temperature requirements at the req
8、uisite duty cycle. Welding Electrodes Ford standard, male, ”, “hi water flow“ electrode caps, with two inch radius face (Ford part number: WC11R263), as specified in WC1-002, will be used for all tests. The electrode caps must be made from RWMA Class 2 CuCr (ISO Type A2/1) material, unless otherwise
9、 specified by the Ford Vehicle Operations Joining Supervisor. The electrode caps, adapters and holders to be used will be found under the following standards: Identification Ford Standard Designation Electrode Cap WC1-002 WC11R263-A2/1 Cap Adapter WB1 WB1S36-1XX Tip Dresser An electric or pneumatic,
10、 automatic tip dresser or a handheld tip dresser is required to dress the top and bottom electrodes to clean, fresh copper during the test setup and test procedures. Cutter blade and holder must be matched to the WC11R263 electrode cap face. Changer & Dresser Corporation Cutter Part Number KTW(U)-14
11、0 and Holder Part Number KTWH(U)-140 or equivalent are required. Knife Edge Caliper Mitutoyo Absolute Digimatic Model No. CD-6”CSX or equivalent is required to measure weld button diameter. FORD LABORATORY TEST METHOD BB 117-01 Copyright 2014, Ford Global Technologies, Inc. Page 2 of 8 Instrumentati
12、on Calibrated Miyachi Weld Tester MM-380A or equivalent, capable of simultaneous measurement of force AND current and/or voltage, is required to set up and document weld schedule. Metallurgical Sample Preparation and Microstructural Feature Measurement Suitable equipment shall be available to cross
13、section, polish, etch, and examine at 10x magnification welded samples. Procedure Surface Preparation of Material The material submitted for approval shall be prepared according to the practice proposed to be used for production quantities. A letter shall accompany the material noting all pertinent
14、data to identify completely the method of preparation. A minimum of 7.5 square meters of material shall be submitted in a width equal to the maximum capability of the surface preparation equipment. The material shall be sheared in 25 mm x 300 mm and 100 mm x 300 mm pieces. Care shall be exercised to
15、 obtain pieces of each size from various positions of its width. All material is to be welded in the as-received condition, with no modification to the temper or surface condition. The Welding Acceptance Test shall be conducted as outlined herein. If failure occurs, the material is rejected. If the
16、material passes the initial Welding Acceptance Test, the unused portion of the submitted material shall be stored on a rack permitting exposure of both surfaces of the sheets to normal shop atmosphere for 90 days. The Welding Acceptance Test is then repeated on the material after 90 days of exposure
17、. Approval Criteria Approval is granted when all of the following conditions are met: (1) Welding Acceptance Test on material before and after 90 days exposure to shop atmosphere produces a minimum of 2500 consecutive acceptable welds on panels without failure. Identical weld parameters are to be us
18、ed on both sets of material (i.e. fresh and post-90-day storage). (2) 25 mm x 300 mm test strips are free of surface expulsion (whiskers), not assignable to operator error. (3) Surface indentation (I1 and I2), as shown in Figure 1, does not exceed 15% of original sheet thickness (t1 and t2, respecti
19、vely). (4) No sheet separation or buckling occurs due to indentation. (5) Surface roughness meets applicable paintability specification requirements. (6) Metallographic acceptance criteria are achieved at setup and at the 2500th weld interval. Following approval, no changes in material or processing
20、 may be made without prior written approval from the responsible Ford activity. I1t1I2t2Figure 1. Measurement of surface indentation FORD LABORATORY TEST METHOD BB 117-01 Copyright 2014, Ford Global Technologies, Inc. Page 3 of 8 Welding Acceptance Test Equipment Setup The electrode caps shall be in
21、stalled in the machine so that they are in precise alignment in the vertical plane and their welding faces are parallel under the electrode force requirement for the thickness of the material under test. Test Setup Procedure The following procedural details shall be followed during the test setup: (
22、1) Contact Ford Vehicle Operations Joining Supervisor for initial weld schedules and weld setup procedures. (2) Dress electrodes prior to commencing setup and after every 5 setup strips. Top and bottom electrode cap faces shall be dressed to clean, fresh copper at each dress interval. (3) Using 25 m
23、m x 300 mm test strips, make six welds on the centerline approximately 35 mm50 mm apart, as shown in Figure 2. (4) Do not measure the first weld on each test strip (the “shunt weld”). (5) Measure the minimum and maximum diameter of the remaining five weld buttons using the method described in the se
24、ction entitled “Determination of Spot Weld Diameter” and record the data on the sheet provided in Appendix A (or similar). (6) Governing metal thickness (GMT) for double panel welding is defined as the thickness of the thinnest sheet. (7) Setup is achieved when the average button diameter of the fiv
25、e measured welds on the strip is 5*GMT, with no single weld falling below (5*GMT 0.5 mm). (8) Note that only button pull / plug failure is deemed an acceptable fracture mode for this weldability assessment. Partial thickness and interfacial fracture areas are not to be included in averages. (9) Setu
26、p shall be confirmed via metallographic examination. A second strip is to be welded at the same settings employed to achieve setup button size. One of the five non shunt welds shall be cross sectioned, polished, and etched as closely as possible through the weld center. The weld shall be examined at
27、 10X magnification for compliance with ESXXX-1B325-XX with respect to nugget diameter, weld penetration, indentation, porosity, cracks, and inclusions. (10) The set points as well as the actual delivered values of secondary current, weld time, and electrode force are to be recorded on the data sheet
28、. (11) After establishing the proper weld button diameter, electrode caps are to be changed and dressed and the test commenced without any additional modifications to the weld schedule. Figure 2. 25 mm x 300 mm test strip with 6 welds at 35 mm spacing FORD LABORATORY TEST METHOD BB 117-01 Copyright
29、2014, Ford Global Technologies, Inc. Page 4 of 8 Test Procedure The following procedural details shall be followed during the test: (1) New electrodes are to be inserted and dressed prior to initiating the 2500 weld test, as per step (11) in the Test Setup Procedure above. (2) Welding is to be condu
30、cted on 100 mm x 300 mm panels. (3) Welding shall be at a minimum rate of 10 spot welds per minute. (4) Welds shall be made on panels one row of welds at a time. To avoid welding on overheated panels, only five consecutive welds are to be made on any given panel before it is set aside and allowed to
31、 cool, as shown in Figure 3. Welding is then continued on different consecutive panels until the required number of panel welds per checkpoint interval is completed. A total of 70 welds per panel is typical, as shown in Figure 4. (5) Tip dress frequency shall be that specified by the Ford Vehicle Op
32、erations Joining Supervisor. Top and bottom electrode cap faces shall be dressed to clean, fresh copper at each dress interval. (6) Welding parameters are not to be altered throughout the duration of the test. Under no circumstances shall the current level be raised above that established during set
33、up. (7) After every 125 welds on 100 mm x 300 mm panels and before tip dressing, make six welds on the centerline of completely overlapping 25 mm x 300 mm test strips, as shown in Figure 2. Tear down the welds via peel and measure the minimum and maximum diameter of the weld buttons using the method
34、 described in the section entitled “Determination of Spot Weld Diameter”. Record the data on the sheet provided in Appendix B (or similar). If the button diameter of each of the five welds on the teardown strip exceeds 4*GMT, the test passes that 125-weld increment. (8) The above steps shall be repe
35、ated until 2500 spot welds are obtained on the 100 mm x 300 mm panels or any one of the five welds on a 25 mm x 300 mm teardown coupon has a button diameter of less than 4*GMT. When this first undersized button is encountered (note that only button diametersnot partial thickness or interfacial fract
36、ure diametersare to be considered), an additional 25 mm x 300 mm test strip shall be welded, torn down, and measured. Failure at a given 125-weld increment shall be firmly established whenever the average button diameter of two or more of the five welds on the second teardown strip fall below the re
37、quired minimum or if there is a single “no weld” / weld with no evidence of fusion (classification 8 in Figure 7), not assignable to welder malfunction or operator error. Note that the determination of button diameter shall be conducted at the 2500 spot weld interval, as well. (9) At the 2500 spot w
38、eld interval, a second metallographic sample is to be prepared. An additional strip shall be welded without tip dressing. One of the five non shunt welds shall be cross sectioned, polished, and etched as closely as possible through the weld center. The weld shall be examined at 10X magnification for
39、 compliance with ESXXX-1B325-XX with respect to nugget diameter, weld penetration, indentation, porosity, cracks, and inclusions. FORD LABORATORY TEST METHOD BB 117-01 Copyright 2014, Ford Global Technologies, Inc. Page 5 of 8 12345678910111213141516171819202627282930212223242531323334353637383940Pa
40、nel 1Panel 6Panel 5Panel 4Panel 3Panel 2Figure 3. Example panel welding sequence 100 mm300 mmFigure 4. Total welds per panel = 70 (5 rows of 14) FORD LABORATORY TEST METHOD BB 117-01 Copyright 2014, Ford Global Technologies, Inc. Page 6 of 8 Determination of Spot Weld Diameter The teardown weld diam
41、eter is the average of the smallest (dmin) and the largest (dmax) diameter of fused material, ( 2 maxmin dd + ), as measured with a knife-edge calipers in a destructive test (see Figure 5). The ratio between dmax and dmin is not to exceed 2:1. dmaxdminWeld buttonFigure 5. Measurement of button size
42、Figure 6. Teardown strip with five buttons Figure 6 shows five buttons pulled out of a welded strip. It should be noted that the fracture mode in a destructive test may not always be a button pull. Additional fracture classifications are shown in Figure 7, but only button pull / plug failure is deem
43、ed an acceptable fracture mode for this weldability assessment. The specific fracture mode must be identified on the test data sheet along with the corresponding average diameter measurement. Note that only a trained and certified operator is to characterize and measure weld buttons. Figure 7. Weld
44、fracture classification (figure source: A/SP) FORD LABORATORY TEST METHOD BB 117-01 Copyright 2014, Ford Global Technologies, Inc. Page 7 of 8 Appendix A: Weld Setup Data Sheet Min button diameter (mm):Setup button diameter (mm):Electrode:Min Max Min Max Min Max Min Max Min MaxS1 boxshadowdwnS2 boxs
45、hadowdwnS3 boxshadowdwnS4 boxshadowdwnS5 boxshadowdwnS6 boxshadowdwnS7 boxshadowdwnS8 boxshadowdwnS9 boxshadowdwnS10 boxshadowdwnS11 boxshadowdwnS12 boxshadowdwnS13 boxshadowdwnS14 boxshadowdwnS15 boxshadowdwnS16 boxshadowdwnS17 boxshadowdwnS18 boxshadowdwnS19 boxshadowdwnS20 boxshadowdwnWeld 1 Weld
46、 2 Weld 3 Weld 4 Weld 5 AverageF1 PreheatF2 CoolF3 WeldF4 CoolF5 ForgePreheat Current Settting: Measured:Top: Bottom:Weld Setup Data SheetTest ID: Test Date:Test Operator:Weld Time SetupStackup (thickness, alloy, pretreatment, lubricant, heat treatment) Preheat Force Settting: Measured:Weld 1 Weld 2
47、 Weld 3 Weld 4 Weld 5 Average button diameter (mm)Button diameter (mm) Button diameter (mm) Button diameter (mm) Button diameter (mm) Expulsion?Button diameter (mm)Final Weld ScheduleCurrent (kA)Force (kN)Time (ms)Strip ID Forge Current (kA) Indicate IForgeIndentationForge Current SetupStrip ID Time
48、 (ms)Indicate Tmin, Tsetup, TexpulsionForge Force Settting: Measured:Forge CurrentForce (kN) and Current (kA) ChecksSettting: Measured:Weld Force Settting: Measured:Weld Current Settting: Measured:FORD LABORATORY TEST METHOD BB 117-01 Copyright 2014, Ford Global Technologies, Inc. Page 8 of 8 Append
49、ix B: Weld Teardown Data Sheet Min Max Min Max Min Max Top Bottomboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxshadowdwn boxshadowdwnboxs
