Avoid Painting the Conveyor?

Question:

We are painting using electrostatic spray guns. Everything is fine concerning the finished parts. The problem is that the paint also coats the hangers, racks and hooks that hold the parts on the conveyor. As you can imagine, cleaning these items is quite a chore. How can we avoid applying paint on the steel hangers, racks and hooks? What are we doing wrong? B.M.

Answer:

Actually, it sounds like you are doing everything right. To take advantage of the higher transfer efficiency provided by electrostatic spraying, your parts must be at ground potential. To obtain a good ground, the conveyor line is connected electrically to an earth ground, which is usually a 6-ft-long copper rod driven into the earth.

The continuity of the electrical ground through the conveyor framework, conveyor chain, hangers, racks and hooks must be maintained with as little electrical resistance as possible for the parts to be at ground potential. Under these conditions, the hangers, racks and hooks will be painted by electrostatic attraction and must be stripped to remove the paint. On the other hand, if they are not stripped, you will diminish the electrostatic attraction because you will have increased the electrical resistance. You have to take the bad with the good.