Builders of production and test equipment often
want to ensure that any electrostatic build-up will be safely discharged to
earth. This can sometimes be a problem with aluminium profile frames, because
the anodized layer is an electrical insulator. 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.
-CATALOGUE
Builders of production and test equipment often
want to ensure that any electrostatic build-up will be safely discharged to
earth. This can sometimes be a problem with aluminium profile frames, because
the anodized layer is an electrical insulator. 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
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.