First progress report on a multi-channel magnetic drum inner ...

IX-14
ribbon consisting of a sturdy backing strip coated with the magnetic
substance. This strip is wound spirally around and around the drum
in a manner similar to the taping of the handle of a tennis raquet.
This winding is done with the magnetically coated side of the strip
down against the surface of the drum. Each turn slightly overlaps the
preceding turn so that the entire drum is covered with the inagnetic
material. The drum is now placed in an oven and baked. Upon comple-
tion of the baking process, the drun. is removed from the oven and the
coil backing is stripped off. Of course, in the process of peeling
off the backing, patches of magnetic material are pulled off the surface
of the drum. Also the drum is imperfectly coated along the spiral
joint of the coiled coated material. These bare spots on the surface
of the drum are touched up by hand with a brush using the same magnetic
material suspended in a suitable thinner,
3. Spraying Process:
The first operation in this process is to spray the
driim with a base coat of a suitable cement. Next, the drum is sprayed
with one or more coats of the magnetic material suspended in a suitable
thinner. This thinner has the property of softening or dissolving the
base coat of cement on the drum slightly so that there will be a good
bond between the magnetic material and the drum. To secure a uniform
coating, the drum is rotated while being sprayed. During the spraying