SAE J400 pdf download
SAE J400 pdf download.Test for Chip Resistance of Surface Coatings.
This SAE Recommended Practice covers a laboratory procedure for testing and evaluating the resistance of surface coating to chipping by gravel impact. The test is designed to reproduce the effect of gravel or other media stflking exposed paint or coated surfaces of an automobile and has been correlated with actual field results. The specific intent of the test is to evaluate organic surface coatings or systems on flat test panels; however, It may be possible to extend this type of testing to finished parts or other types of materials such as anodized aluminum or plated plastics if the results are interpreted with respect to the limitations and intent implied by the original testing procedures and rating system.
This document may involve hazardous materials, operahons, and equipment. This document does not purport to ad&ess all of the safety problems associated with its use. It is the responsibility of whoever uses this document to consult and establish safety and health practices and determine the applicability of regulatory limitations prior to use
All dimensions are nominal unless otherwise noted.
2. Reference
2.1 Related Publication—The following publication Is provided for information purposes only and Is not a required part of this document.
SAE PUBLICATION—Available from SAE, 400 Commonwealth Drive. Warrendale, PA 15096-0001.
SAE 680046—Measurement of Chipping of Organic Coatings for Automobiles. John T. ‘ibung and Donald
R. Hays. Ford Motor Co., Indust. and Chemical Products Div., Warrendale, PA. USA, Society of Automotive Engineers, Inc.. 1968
4.2 Gravel—The gravel for this test shall be water-worn road gravel, not crushed limestone or rock. The gravel will pass through 15.86 mm (5/8 in) space screen when graded, but be retained on 9.53 mm (318 in) space screen. It is important to note that mesh screen is not a substitute for space screen. The gravelometer has 9.53 mm (3/8 in) space screen in the bottom to separate fractured p.eces of rock and ist smaller than 9.53 mm (3/8 in) so that the retained gravel on this screen may be reused. Because the gravel tends to blunt or fragment after repeated impacts, it should be changed at a regular frequency. Foi testers that ai’e operated on a weekly basis, 2 prnts of gravel shall be replaced with fresh gravel each month. For testers that are operated on less frequent basis, 2 pints of gravel shall be replaced with fresh gravel at least every 6 months.
Gravel must be washed prior 10 initial use.
Other media may be used as agreed upon by contractual parties.
NOTE— Pint measurements refer to a 1 pint container full to the top.
4.3 PaInt Removal Tape—b cm (4 in) wide or 5 cm (2 in) wide, 3M product #898 filament strapping tape or equivalent. Other tape may be used as agreed upon by contractual parties.
NOTE— The adhesion strength of the tape use makes a significant impact on how much separated paint is removed.
4.4 Temperature CondItIoning Equipment—Gravelometer tests are usually run at ambient or a lower temperature, generally —29 C (—20 °F). which shall be mutually agreed upon by contractual parties. Tests conducted at different temperatures will employ the following:
4.4.1 METHOD A—A cold room chamber in which the gravelometer and test panels are maintained at the specified temperature of testing.
For freezers that employ a defrosting mechanism, document the method of defrosting and any temperature changes.
4.4.2 METHOD B—A freezer in which the test panels are cooled to 5.6 °C (10 F) below the test temperature before they are individually transferred and tested Immediately in a gravelometer at room temperature located nearby.
4.4.3 METHOD C—Ambient: room maintained at a temperature between 20 C (68 F) and 30 C (86 F).
4.5 Transparent Grid—A chip counting aid constructed of transparent plastic approximately 3.2 mm x 12.7 cm (118 x 5 x 5 in), on which a 10.16 x 10.16 cm (4 x 4 in) grid of 2.54 cm (1 in) squares has been etched or scribed,
4.6 ChIppIng Rating Standards—A photographic transparency, depicting the size and shape of each chip. See Figure 3 for representation of this transparency. Figure 3 IS A REPRESENTATION ONLY.
