1、 FORD LABORATORY TEST METHOD BO 158-03 Date Action Revisions 2001 04 02 Revised Editorial no technical change A. Cockman 1992 04 30 Printed copies are uncontrolled Page 1 of 3 Copyright 2001, Ford Global Technologies, Inc. DETERMINATION OF CHEMICAL STRESS CRACK RESISTANCE OF PLASTIC PARTS UNDER MECH
2、ANICAL STRESS Application This procedure is used to determine the chemical stress crack resistance of plastic parts under specified mechanical stress. Apparatus Required Tensile Test Machine With a constant rate of jaw separation of 50 mm/minute and a recording device. Bending Template With known cu
3、rvature of radius, made of stainless steel (see Sketch 1). Glass Container Readily sealable (i.e. desiccator) for test reagent. Hose Clamps (minimum 2 pieces) For fixing the test specimen on the bending template. Sliding Caliper Water Absorbing Tissue Various Test Agents As specified by the Relevant
4、 Materials Specification. Micrometer Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere 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 other
5、wise specified. FORD LABORATORY TEST METHOD BO 158-03 Page 2 of 3 Copyright 2001, Ford Global Technologies, Inc. Procedure 1. Determine the thickness of the test specimen with a micrometer accurately to within 0.01 mm (test slab according to ISO R 527, Type B, Figure 2, but 3.2 +/- 0.05 mm thick). 2
6、. Calculate the bending radius (r) of the template by entering the thickness (d) into the attached formula to achieve the surface strain (Eb) of the test beam according to specification requirement. Calculation of the surface strain (Eb): Eb = d x 100 d = thickness of the test beam (2 x r + d) r = r
7、adius of the template Calculation Example: Thickness of test beam d: 3.20 mm Required Eb : 0.70 % Calculate the radius of the template as follows: r = (100 x d) - (E b x d) = (100 x 3.2) - (0.7 x 3.2) = 227 mm 2 x Eb 2 x 0.70 3. Tighten the test slab onto a template of suitable radius of curvature (
8、as calculated in para 2) with two hose clamps (see Sketch below). Sketch 1: Metal Template with Tightened Test Slab FORD LABORATORY TEST METHOD BO 158-03 Page 3 of 3 Copyright 2001, Ford Global Technologies, Inc. 4. Submerge the tightened test slab into the glass container filled with the test agent
9、 and seal it. 5. After storage time as described in the test specimen remove the test slab from the template and dry with water absorbing tissue. 6. Examine the sample visually for stress cracks and rupture. 7. Determine the tensile strength and/or elongation by tensile test (according to ISO R 527)
10、 within 30 minutes after removing the test slab from the test agent (according to specification requirement). 8. Repeat the test at least 5 times. Evaluation Ascertain the average value of the elongation or tensile strength measurements and determine the percentage decrease from the original value (based on 5 measurements minimum). 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.
