The science behind the process
In Electrocoating, positively charged paint particles are deposited on to a negatively charged work piece. Its is a relatively environmentally friendly process and it is largely water based.
Pre-treatment is key to achieving the best possible finish. It begins with cleaning; ideally the piece should be presented to us in a clean condition, the cleaner the part to begin with the higher the quality of the end coating. However, we use mild alkaline cleaners both on and off line so as to avoid contamination of the system, so workpieces with a light coating of water soluble oils are fluids are ok. However, heavy oils, grease, rust and scale can all reduce the effectiveness of the cleaners. Once parts are cleaned, they are rinsed and have a layer of zinc phosphate crystal applied. This enhances corrosion resistance of the coating, prevents creep and consolidates the subsequent paint finish.
After pre-treatment and rinses, the work pieces enter the electrocoat bath. At this stage a negative charge is placed through the work piece, causing the positively charged particles in the paint solution to become deposited (opposites attract) in a uniform coating. As the work piece gradually becomes covered, it is insulated from the current, meaning the process spreads across the surface of the work area until it reaches all recesses and coats them evenly. We use PPG Powercron 6200 HE cathodic epoxy paint, the very latest in edge protection protective coatings to ensure that even even sharp edges on metal pressings have improved coverage.
Once the part is coated it is submerged in a series of post paint rinses which remain part of the "closed-loop" paint system. The purpose is to recover any carry-over of paint solids to the rinse tanks (also known as cream coat). These solids are returned to the paint tank as part of a complex filtration system. The advantages of this are cleanliness, consistency and minimal paint wastage, all of which aids efficiencies and keeps costs low.
.The final stage of the automated coating process is the oven bake cycle, here the coating is cured to tightly controlled time and temperature requirements. Once cooled parts are ready for our individual inspection, packing, further assembly operations (where required) and shipping.