VII Accessibility
Most designs of closed construction require access
to the interior. In many cases, this is a removable
slip-fit cover or a bolted access cover plate. If pos-
sible, the cover should be located on a side parallel
to the interference field in order to minimize the
magnetic impedence effects of the resulting air gap.
Cover to main shield joints should have metal to
metal contact and one-half inch minimum overlap to
maintain flux transfer.Access ports of various sizes are often required. Aspreviously stated, an interference field will penetrate
any shield opening to a depth of approximately one
diameter. As an alternative to locating sensitive
equipment away from openings, uncapped extension
cylinders approximately one opening diameter long
can be welded to the main cylinder. Extensions will
prevent interference fields from entering the shield
chamber through the ports.To maintain uniform flux density, the
shielding mate-rial between holes should equal one hole diameter.
Of course, to minimize
shielding costs, the number of
access ports, covers and extensions should be kept
to a minimum.
IX Operation at High Vacuum
CO-NETIC AAAlloy is specially formulated for maxi-
mum magnetic
shielding properties and has some
physical properties similar to stainless steels. Out-
gassing is minimal and cleaning for high vacuum
applications can follow the same procedures used for
stainless steel. Handle annealed magnetic shields
carefully to avoid severe deformation which causes
reduced attenuation.
X Source for Shielding
Magnetic Shield Corporation has provided many dif-
ferent shapes and sizes of
shielding chambers, up to
8 feet in diameter. We have annealing facilities avail-
able that are capable of accommodating large
shields.Please call to discuss design or fabrication require-ments or send a sketch for prompt quotation.
VIII Construction
Preferred chamber construction is heliarc butt seam
welds. To make a uniform, full fusion joint, a strip of
the parent alloy is used as a filler rod during welding.
After fabrication, controlled atmosphere annealing isrequired to develop maximum permeability in the
material. After annealing, any required non-magnetic
spacers are assembled between layers of multi-layer
shields to maintain concentricity. Shields manufac-
tured by Magnetic Shield Corporation are inspected
after each operation and the complete assembly is
given a magnetic attenuation test to confirm the
theoretical performance calculations.
Magnetic Shield.... the Preferred Source
MAGNETIC SHIELD CORP. Perfection Mica Co.740 N. Thomas Drive
Bensenville, IL60106 U.S.A.
CATALOG CV-1D Fax 630-766-2813 Phone 630-766-7800
Printed in the U.S.A.
