MadSci Network: Engineering

Re: How do you get rid of static charges

Date: Thu Jul 27 16:18:39 2000
Posted By: William Beaty, Electrical Engineer / Physics explainer / K-6 science textbook content provider
Area of science: Engineering
ID: 962517505.Eg

Hi Lanny!

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 would stop.

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.

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