|MadSci Network: Engineering|
This is a common problem in industry. The veneer is
accidentally being electrically charged by the production
machinery, and then when it is placed near a metal object
(your cart), the metal object also becomes electrically
charged. Physics books call this charging by induction,
and the veneer doesn't even have to touch the cart in order
to charge up the metal.
One simple solution: get rid of the metal carts, and
use plastic ones! Or use wooden carts. The "induction
effect" only causes problems with metal, and if the
carts were made from an insulating material, the shocks
A less-simple solution: find out how the veneer gets
electrically charged, and put a stop to it. Perhaps it
is getting charged up by contact with a pressure roller,
or some metal blade is dragging across it. This can
produce contact electrification on the surface
of the veneer. One way to eliminate this charge is to
raise the humidity in the room (raise it above 70% R.H).
Another method is to stetch a long piece of tinsel-covered
wire through the production machinery, so the tinsel
passes very close to the surface of the veneer as the
veneer moves along. The tinsel-wire must be placed
downstream from the spot where the veneer becomes
charged. The tinsel-wire must be connected to
electrical ground, and the sharp edges of the
tinsel will drain the charges out of the veneer.
A ground rod or ground chain on the cart will not
work unless the floor is made from a conductive material.
If you can't replace the metal carts, you could try
covering them with some sort of thick plastic, but
I doubt this will work. Since the sparks are jumping
six inches, the voltage on the carts is extremely
large, and the sparks will probably jump right
through a thin plastic coating.
Try the links in the MadSci Library for more information on Engineering.