Heat treating and inspection of metals Page: 56
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48-49 AIR CORPS
(3) Demagnetization.-As previously mentioned, parts must be de-
magnetized after each inspection and prior to final cleaning. In all
cases, this is accomplished by passing the parts slowly though one of
the demagnetizer coils shown in figure 10. When demagnetizing
parts that are small in comparison to the demagnetizing unit, care
should be used to pass the part close to the coil wall rather than
through the center of the opening. Demagnetization must be done
after each inspection and before final cleaning.
(4) Cleaning of parts.-After demagnetizing, parts may be freed
from adhering inspection material by dipping or vigorous "slushing"
in the rinsing bath. This operation should be carried out before the
inspection liquid has had an opportunity to dry on the surface of the
49. Maintenance.-Very little maintenance work is required in
connection with the magnaflux equipment. Maintenance consists
chiefly in proper care of the batteries and thorough cleaning of the
a. Care of batteries.-When the magnetizing unit is in constant use,
the specific gravity of the batteries should be checked daily with a
hydrometer. This reading must not fall below 1.272 (at 80 F.) and
the charger should be regulated to maintain this condition. Whenever
the electrolyte is found to be less than 1/2 inch above the plates, dis-
tilled water should be added to bring it to this level. The batteries
must be kept clean and dry at all times. Batteries may be cleaned by
means of a cloth moistened with a solution of carbonate of soda and
water. A small amount of petrolatum spread over the terminals will
help prevent corrosion.
b. Cleaning of magnetizing unit.-The unit should be kept free of
all accumulations of dried inspection material by washing with the
rinsing solution. In order to assure proper circulation of the inspec-
tion medium, the sump screen should be cleaned daily. Due to the
high amperage flow, the main contactor points must be kept free of
corrosion by frequent cleaning with fine sandpaper.
c. Miscellaneous.-(1) Inspection medium should be renewed and
the tank cleaned whenever it becomes fouled with dirt, grease, chips,
and other foreign material. Should it become low in ferromagnetic
content, magnaflux paste should be added.
(2) Pump and motor used for circulating the medium should be
checked monthly for lubrication. When necessary the bearings should
be lubricated with a suitable cup grease.
[A. G. 062.11 (1-30-41.)]
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United States. War Department. Heat treating and inspection of metals, book, September 10, 1941; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc96657/m1/58/: accessed July 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.