|
The fasteners used usually do not guarantee an
electrical connection, particularly over the longer
term: once even the smallest amount of corrosion has set
into the joint area, any continuity may be lost. Many
tests have been conducted by Item over a long period to
solve this problem. Item has now introduced a version
of its Standard Fastener (a two-part fastener consisting
of a special button-head screw and load-spreading
plate), whereby the screw has been subtly altered just
under the head. This alteration guarantees that when
tightened, the screw destroys and displaces the
anodising immediately around it, giving a guaranteed
connection to one piece of profile. The other piece is
already connected by virtue of the machined thread in
the profile. The screw is designed such that the normal
function of assembly and ease of fitting the two
profiles together before tightening the screw, is not
affected.
 For
the Universal and Automatic type fasteners, which cannot
be easily altered, a simple ESD steel pin is available
which is lightly driven into the central bore of one
profile, making good contact. The pin head then destroys
the anodising of any subsequent profile to which the
first profile is fitted, making electrical contact.
Both ESD fittings work in such a way that if the
profiles are subsequently disassembled, the marks are
hardly noticeable, so the increasingly important
re-usability feature of the profiles and parts is not
compromised.
The ESD fittings are the latest addition to the Item
range of electrical discharge related products. These
include Potential Equalisers which can be retro-fitted
to provide ESD connections, and Earthing Terminals where
a safety circuit is needed.
|
