The six steps taken in the fusible alloy process are as follows:
Coat the inner surface of the tube to be bent with a light
engine oil, specifications MIL-L-6082A.
Close one end of the tube.
Place fusible alloy in a clean steel ladle and submerge both
tube and ladle in a hot water tank. The fusible alloy stays in
the ladle, not combining with the hot water.
When the alloy has melted, pour it into the tube to be bent,
keeping both the tube and ladle under water. As it fills the
tube, the alloy displaces the water from the tube.
After the
tube is full of alloy, remove it from the water and quench it
in cold water or air cool until the alloy is completely
solidified.
The tube is now solid and can be bent with any suitable bending
tool.
As this alloy bends readily when cold but breaks when
warm or under suddenly applied loads, care must be taken that
the alloy in the tube is bent slowly.
When the bending is completed submerge the tube in hot water
and allow the alloy to run out of the tube into the ladle or
other suitable container.
All of the alloy must be removed
from the bent tubing, as the alloy will cause corrosion. Also,
any alloy left in the tube will obstruct the tube and alter the
flow characteristics of the fluid.
TUBE CONNECTIONS
Three basic types of connections are used with aircraft tubing. The
two most common, the military standard (MS) flareless connection and
the flared connection, are depicted in Figure 2-7.
The third, less
frequently used is the beaded connection.
NOTE:
Army-Navy
standards
(AN)
designated
for
government standards were changed over to
military standard (MS) designations.
38
AL0907
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