1、 FORD LABORATORY TEST METHOD BU 003-02 Date Action Revisions 2000 11 10 Revised Editorial no tech nical change A. Cockman 1992 03 02 Printed copies are uncontrolled Page 1 of 4 Copyright 2000, Ford Global Technologies, Inc. BLOCK SHEAR STRENGTH OF METAL TO METAL ADHESIVES Application This procedure
2、is used to test the block shear strength of thermosetting adhesives used for bonding metal to metal. Apparatus Required Press An air driven press which will deliver a constan t pressure to the test specimens during cure is required. The press is equipped with controlled electric heaters which heat t
3、he test specimens to required temperature during cure under pressure. (See sketch.) Oven A mechanical convection oven maintained at 175 +/ - 5 F is required for drying the adhesive coating. Tensile Tester A tensile testing machine with a scale range of 0 - 10,000 lbs and capable of applying a load a
4、t a uniform rate of 0.050 inch/minute is required. The tensile machine shall have an indicator for recording the shear strength in pounds of the adhesive at the moment of rupture. Shear Strength Fixture The fixture for holding the bonded test specimen during loading is shown in the attached sketch.
5、The fixture is equipped with an elec trically controlled heater for determining shear strength at elevated temperatures. Abrasive Paper or Sand Blast Alundum, 4/0 150 grit with cloth backing, is used for polishing the mating surfaces of the test specimens or sand blast (depending on surface desired)
6、. Sand or Grit Size on #20 Sieve - 12 % max on #50 Sieve - 1 % max Pressure used - 100 psi FORD LABORATORY TEST METHOD BU 003-02 Page 2 of 4 Copyright 2000, Ford Global Technologies, Inc. Exposure time - 30 seconds per square inch Nozzle distance to specimen - 3 inches Nozzle size - 3/8 inch Test Sp
7、ecimens Each test specimen assembly consists of one strip and one disc of 24ST aluminum. The strip is 1 1/8 by 4 3/8 x 1/4 inch and the disc is 1 1/8 inch diameter by 1/4 inch thick. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled a
8、tmosphere of 23 +/ - 2 C and 50 +/ - 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure 1. Polish the mating surfaces of an aluminum strip and disc to a sm ooth uniform surface with 4/0 150 grit alundum polishing c
9、loth. 2. Wipe clean with a cloth wetted with ESF - M5B99 - A Trichloroethylene. 3. Lay a number of the aluminum strips on a flat surface with their long edges touching and parallel. Lay three layers of 0.007 inch thick tape across each end of the test specimens as shown. This buildup of tape will as
10、sist in leveling a 0.021 inch thick layer of wet adhesive across the center of each test specimen. Spread and level the adhesive with a spatula. FORD LABORATORY TEST METHOD BU 003-02 Page 3 of 4 Copyright 2000, Ford Global Technologies, Inc. Note: This procedure should give approximately a 0.007 inc
11、h thick dry film thickness with a 40 % total solids adhesive. To obtain the 0.006 - 0.008 inch total dry film thickness desired with less total solids, more thickness of tape will be necessary. Four layers of 0.007 inch tape would be required with 26 % solids adhesive. 4. Remove the tape and air dry
12、 the specimens for 15 minutes followed by a bake in the oven for 20 minutes at 175 +/ - 5 F. 5. Cool to 23 +/ - 2 C and bond an aluminum disc to t he coated area of each aluminum strip with finger pressure. 6. Position the test specimen in the press, locating the hole in the disc over the pin in the
13、 press and apply the required load for the time and temperature as indicated by the material specifica tion or laboratory request. 7. Allow the bonded specimens to cool, position in the test fixture used for shear adhesion (see sketch) and apply a load at 0.050 inch per minute to failure of the bond
14、. The temperature at which the shear strength test is det ermined shall be as specified on the laboratory request. 8. Report the shear strength of the specimen in pounds, temperature of the test, type of adhesive, cure time and temperature. Chemicals, materials, parts, and equipment referenced in th
15、is document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD BU 003-02 Page 4 of 4 Copyright 2000, Ford Global Technologies, Inc. BLOCK SHEAR STRENGTH OF METAL TO METAL ADHESIVES Block Shear Strength Test Fixture (Exploded View)
