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TAPE WOUND CORE CONSTRUCTION
Tape wound cores are fabricated on specially designed machines
which wind insulated tape onto a mandrel under controlled tension
to provide an extrememly uniform
cross-section.
The wound cores are then annealed in a hydrogen or other atmospheres. This develops
the required magnetic characteristics previously determined by careful raw material
selection and process control.
Annealed cores are sensitive to mechanical strain in varying degrees depending
upon the alloy. These strains cause changes in the magnetic characteristics of
the material which may severely alter the performance of the finished core. To
prevent these changes from taking place, the annealed tape cores are housed within
cases which protect them from the strains of electrical winding and other external
disturbances. (see Figure 3.)
The cases are fabricated of various materials depending upon the intended application:
Plastics, such as phenolic, nylon, glass reinforced nylon and metals, like aluminum
are used.
A damping medium fills the space between the core and the case to minimize the
motion of the core within the case, thus reducing the possibility of change in
electrical characteristics under shock and vibration.
The non-metallic cases (glass-filled nylon, phenolic, nylon) are the most widely
used. The glass filled nylon case has proven superior to the phenolic case because
of its greater strength. Aluminum cases provide greater environmental protection
and this quality can be further enhanced by the application of an epoxy finish
over the case.
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