FLTM BI 107-1涂层试验片的碎石冲击试验.pdf

FORD LABORATORY TEST METHOD BI 107-01 CHIP RESISTANCE TEST FOR PAINTED PANELS Application This method is used to determine the chip resistance of painted panels and body parts and painted plastic panels and parts. Apparatus Required Gravelometer The gravelometer (see Figure 1) consists of an elongated box with a hopper and nozzle system on one end and a slot for the insertion of a test panel on the other end. Steel shot is poured into the hopper where a stream of air propels the shot onto the test panel. The nozzle-system consists, beginning from the main line air supply side of a 200 mm, 12.7 mm air inlet pipe with an inner diameter of 11.5 mm, a tee-piece to fix a pressure gage with a range of 0 to 1.6 bars, a 150 mm, 12.7 mm air inlet pipe with an inner diameter of 11.5 mm, and a nozzle which is exactly described in Figure 2. To guarantee a laminar air stream during the test, all pipes have to be polished on the inner surface. From the inlet to the outlet of the air the inner diameter of the pipe system must be exactly 11.5 mm. The joint from the main line air pressure to the pipe has to be made by a 2 m, 25 mm metal hose. The test air pressure will be adjusted by a ball cock. This cock is fixed behind the main line air pressure gage. This gage has a range of 0 to 16 bars, and it is used to control the static pressure at closed cock. During the test the flow pressure must be controlled by this gage all the time. A second gage of a range from 0 to 6 bars must be fixed immediately behind the ball cock. By this gage it