1、 FORD LABORATORY TEST METHOD BO 127-03 Date Action Revisions Rev. 04 2016 07 05 Revised See Summary of Revisions L. Schmalz, NA 2006 06 21 Revised Updated application, test bars, Step #5 under Procedure, the percent Strain rate deflection Added chemical in agent table L. Schmalz 1994 12 20 Released
2、Controlled document at www.MATS Copyright 2016, 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 contact with other materials, such as
3、oil, grease, cleaners, flexible PVC 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 should be tested with grease used on fasteners; vi
4、nyl 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 Mechanical Convection Oven Conforming to ASTM E145 Type IIA normal oven or equivalent and capable of maintainin
5、g the specified temperature within +/- 1 C. Test Fixtures Construct a mandrel 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 resul
6、ts. Source: Automate Industries Inc. 1906 Brinston Troy, MI 48083 Phone: 248-740-7022 Stereo Microscope 20X magnification AATCC Crockmeter Cloth (style 3) 80 x 84 thread count, combed cotton, desized, bleached (no optical brightener or finishing material present). Source: Test Fabrics, Inc. P.O. Bo
7、x 26 415 Delaware Ave. West Pittston, PA 18643 Phone: (717) 603-0432 FORD LABORATORY TEST METHOD BO 127-03 Copyright 2016, Ford Global Technologies, LLC Page 2 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 bar
8、s shall be prepared. In the instance of material suspected of exhibiting anisotropy, specimens should be obtained parallel and perpendicular to the “material flow“ and should be identified as such. 2. Care should be taken to assure that the test fixtures are carefully cleaned prior to each test to a
9、void possible contamination from previous tests. Assemble the tensile bars in the test fixtures to achieve the 1% strain level (or as specified in the engineering document). The back of the samples should fully contact the test fixture to achieve the desired strain level. 4. Examine the samples thro
10、ughout the gauge length for cracks using 20X on the stereo microscope (after application of stress, but prior to application of the chemical agent). This is to establish the initial strained condition. 5. Apply the chemical agent (within 2 hrs. of assembling the test bar onto the test fixture) to a
11、minimum of three tensile bars. (Do not apply the chemical agent to one bar that will serve as the “control”). . Liquid Chemical Agent (oil or cleaners) Test bar and fixture should be totally immersed in liquid chemical agent. Otherwise, 2 pieces of cotton crock cloth should be placed on top of each
12、other in the strained area of the test bar, and saturated with approximately 1 ml of the agent. Replenish every 24 hours with new crock cloth. High Viscosity Chemical Agents (grease) 0.2 grams applied to the strained area of the test bar. Flexible Chemical Agents (PVC or elastomer sheets) Overlaid o
13、n the strained area of the test bar. 6. Expose the samples for 72 hours at 80 +/- 2C. Expose the control sample in a separate oven in order to avoid contamination. 7. At the end of the test period, remove the chemical agent mechanically or by wiping with a soft cloth. DO NOT USE A SOLVENT. 8. Allow
14、the strained sample to condition for 1 h at 23 +/- 2C and 50 +/- 5% relative humidity. 9. Using a stereo microscope, examine the strained sample for cracking and crazing at 20X magnification while the sample is still in the test fixture. 10. Report the chemical agent, amount, application frequency a
15、nd the presence of cracking or crazing. Bend Radii Required to Produce 1% Strain for 4.00 mm Thickness Sample Thickness (mm) % Strain Radius (mm) 4.0 1 198 For other sample thicknesses, the following formula may be used to determine the correct radius: R = T x 100 1 2 E Where R = radius T = test sam
16、ple thickness E = % strain FORD LABORATORY TEST METHOD BO 127-03 Copyright 2016, Ford Global Technologies, LLC Page 3 of 3 Summary of Revisions 2016 07 05 Removed ASTM D573 reference for oven, as it referenced ASTM E145. Added AATCC Crockmeter Cloth (style 3) Removed initial conditioning Removed Chemical Agent table 2006 06 21 Updated application, test bars, Step #1, 3, 5, 6, 7 Added Possible Chemical Agents for Chemical Compatability 2005 01 12 Revised Text Fixtures, Stereo Microscope; Procedure 1, 3, 5, 6, 8, 9, 10; Chart 1; deleted Figure 2 2001 03 28 Editorial Revision
