1、 FORD LABORATORY TEST METHODBO 127-03Date Action Revisions 2006 06 21 Revised Updated application, test bars, Step #1, 3, 5, 6, 7 Added Possible Chemical Agents for Chemical Compatability L. Schmalz 2005 01 12 Revised Rev Text Fixtures, Stereo Microscope; Procedure 1, 3, 5, 6, 8, 9, 10; Chart 1; del
2、eted Figure 2 L. Soreide 1994 12 20 Printed copies are uncontrolled Copyright 2006, Ford Global Technologies, LLC Page 1 of 3 STRESS CRACKING TEST FOR PLASTICS Application This procedure is used to determine the resistance of thermoplastic materials to stress cracking when they are used in direct co
3、ntact with other materials, such as oil, grease, cleaners, gasketing, plasticizers and elastomers. All amorphous materials (such as PC, PC/ABS ABS, SMA, ASA, PPO) should be evaluated for potential incompatibility with other materials that they may come in contact with. For example, polycarbonate sho
4、uld be tested with grease used on fasteners; vinyl should be tested for compatibility with the substrate material they are covering. If in doubt, contact the Design and Release Engineer for a specific list of agents. Apparatus Required Oven As described in ASTM D 573 Test Fixtures Construct a mandre
5、l from chemically inert materials such as wood or aluminum with the radius needed to achieve the required percent strain. The samples should be attached to the mandrel in a manner which will not interfere with the test results. The bars shall be bent per Figure 1 to achieve the desired strain level
6、and attached at the ends to maintain the desired radius. Source: Automate Industries Inc. 1906 Brinston Troy, MI 48083 Phone: 248-740-7022 Fax: 248-740-7033 Stereo Microscope 20X magnification minimum Conditioning and Test Conditions All test values indicated herein are based on material conditioned
7、 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 otherwise specified. FORD LABORATORY TEST METHODBO 127-03Printed copies are uncontrolled Copyright 2006, Ford Global Technologies, LLC Page 2
8、of 3 Procedure 1. Prepare Type 1A and 1B bars per ISO 527-2 or as agreed upon by the Ford Materials Engineer. A minimum of four tensile bars shall be prepared. In the instance of material suspected of exhibiting anisotropy, specimens should be obtained parallel and perpendicular to the “material flo
9、w“ and should be identified as such. 2. Condition test bars for 24 h at 23 +/- 2 C and 50 +/- 5% relative humidity. 3. Assemble the tensile bars in the appropriate test fixtures to achieve the 1% (or as specified in the engineering document) strain level. Care should be taken to assure that the test
10、 fixtures are carefully cleaned prior to each test to avoid possible contamination from previous tests. Bend the samples over the test fixture and attach the samples. The back of the samples should fully contact the mandrel to achieve the desired strain level. 4. Examine the samples for cracks using
11、 the stereo microscope (after application of stress, but prior to application of the “contact“ material). This is to establish the initial strained condition. 5. Apply the contact material (within 2 hrs. of assembling the test bar onto the fixture) to a minimum of three tensile bars of each strain l
12、evel to assure intimate contact. (Do not apply the contact material to one bar at each strain level. This bar will serve as a “control“ sample for the specific strain level.) . Contact material should be prepared as specified per the manufacturers directions. . Contact material that is flexible such
13、 as sheet vinyl, gasketing or elastomers may be overlaid on the test specimen and secured in the fixture. . Contact materials with high viscosity such as grease and paste should be applied by coating the tensile bar. . If applicable, the test bar and fixture assembly should be totally immersed in li
14、quid contact materials. Otherwise, gauze should be placed in the strained area of the part, saturate the gauze with the contact material, replenish every 24 hours or as needed to keep the gauze saturated. 6. Expose the samples for 72 hours at 80 +/- 2 C. Expose the control sample in a separate oven
15、in order to avoid contamination. 7. At the end of the test period, remove the contact material mechanically or by wiping with a soft cloth. DO NOT USE A SOLVENT. 8. Allow the strained sample to condition for 1 h at 23 +/- 2 C and 50 +/- 5% relative humidity. 9. Using a stereo microscope, examine the
16、 strained sample for cracking and crazing at 20X magnification while the sample is still in the straining fixture. 10. Report presence of cracking or crazing. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for deter
17、mining proper use and handling in its facilities. FORD LABORATORY TEST METHODBO 127-03Printed copies are uncontrolled Copyright 2006, Ford Global Technologies, LLC Page 3 of 3 Figure 1 Deflection (D) in 63.50 mm % Strain 3.35 mm 1.0 Mandrel Radii Required to Produce 1% Strain for 4.00 mm Thickness S
18、ample Thickness (mm) % Strain Mandrel Radius (mm) 3.2 1 158 4.0 198 For other sample thicknesses, the following formula may be used to determine the correct mandrel radius: R = T x 100 1 2 E Where R = mandrel radius T = test sample thickness E = % strain Possible Chemical Agents for Chemical Compati
19、bility Chemical Type Example Window Cleaner WindexTM Vinyl Protectant Motorcraft Custom Vinyl Protectant ZC-40A After Market Cleaners Motorcraft Dash and Vinyl Cleaners ZC-38-A or Motorcraft Spot and Stain Remover-Upholstery ZC-14 Sunscreens Coppertone SPF30TMWaterproof Suntan Lotion Lubricants Mult
20、ipurpose Grease XG-4 Perspiration, Perspiration solution per FLTM BI 113-07 Soft drinks, orange juice Coke, Pepsi, Minute Maid etc Acetone Finger nail polish remover, Methyl Ethyl Ketone (MEK) Paint products, adhesives VM & P Naptha Petroleum based cleaners Phthalate Ester PVC Methyl Alcohol Windshield washer solvent Ethylene Glycol 50/50 coolant water mix Fuel I-Gasoline Fuel C + 15% by volume ethanol Engine Oil Commercially available engine oil
