This question is frequently asked of paint systems and equipment suppliers, and, in most cases, the answer is “Yes”. Since Harold Ransburg invented the electrostatic process just after WWII, there has been more than a few refinements and improvements to the process. Today, most plastic parts for automobiles are finished with electrostatic applicators. Non-conductive substrates are made conductive by basically two methods: the application of a prep coat, conductive primer, or conductive adhesion promoter, prior to the electrostatic application; or by the introduction of a conductive “buck” to the part racks. Wood substrates can be finished electrostatically by maintaining 6% moisture content or by the prep coat method. Applying a conductive material prior to the electrostatic application can be done with conventional applicators or, if a prep coat material is used, with a prep coat tunnel. It is important that the racks are conductive and that a good ground is maintained from the rack to the conveyor to ground. The conductive material must also be used to “paint” the part to the rack thus causing the part to be grounded to the rack. Failure to “paint” the part to the rack can greatly reduce transfer efficiency and even create the conditions that could lead to a static build up on the parts with the potential for a discharge of electrostatic energy.
Grounding is the key to reaping the benefits of electrostatics’ transfer efficiency while insuring maximum system safety. Metal bucks employ the same concept as a magnet through a piece of paper. When you place a piece of metal on a paper and place a magnet under the paper you can move the metal with the magnet. A similar event occurs when a metal casting of the back of a plastic part is incorporated in to the paint rack for that part. The grounded rack and casting is what attracts the charged paint. The plastic part just “gets in the way”. Most automobile fascias are processed in this manner. The paint cost savings and quality improvements of electrostatic painting are huge. Often the return on investment is in weeks rather than years. Cost savings along with reductions in VOCs make electrostatic painting an ever improving method for finishing your parts. Thierica Equipment Co. has the experience and knowledge to guide you through this decision making process no matter if you are purchasing a new paint system or looking for ways to improve your existing line. All our sales people have “process engineering” experience with companies very much like yours. No one is better suited to help you with your paint finishing needs.