Electrocoating or electroplating is also known as electrophoresis or electrodeposition or electropainting. It is a major development from in waterborne coating. Principally it is used the electric attraction force between the different charge. The metal painted object is charged as anode or cathode while the paint solution are the ionic solution with the opposite electric charged. The ionic paint is attracted to attached to the metal object. Although it is seem simple but the processing for applying the coating are rigorous and very careful formulating is very important.
It only work for metal object.The metal need to be pretreated well before go to the painting process. The metal objects to be painted are hung at the overhead conveyor and substantial electrical connection are made. The objects are immersed in the paint solution with the opposite charge. The solution is a low solid (about 5% - 20% solution) and waterborne. The object can be anode or cathode, while the particle paint carry an opposite charged from the object being painted.
The anodic system is the system when the object being paint is the anode or positive electrode. The paint immersion is negatively charged. The paint thickness is controlled by the adjust the immersing time, the voltage and the bath solution. Usually a thin film coating is used about 1 or 2 mill thickness. After the object has coated, they emerged from the pollution and go to the cleaning when they are cleaned from the paint excess and then go for the baking. Baking scheduled are vary according to the type of paint and final properties needed.
The cathodic system is the opposite. The paint solution carries positive charged while the object is the negative electrode. Both the anodic and and cathodic system is very similar but the properties of paint result is not the same. Anodic systems apply paint to positively charged substrates. The negatively charged pigment and resin particles deposit onto the substrate (anode). One disadvantage of this process is that substrate metals dissolve and become incorporated into the coating, which affects surface properties.
Cathodic electrocoating deposits paint onto negatively charged substrates and offers several advantages over anodic electrocoating. The metal dissolution of the substrate does not occur, cathodic electrocoating has the ability to deposit over contaminants, corrosion resistance is improved, and a better color consistency occurs over welded areas.
The paint bath has to be stirred or circulated to keep at the workable concentration. The replacement of coating material must be added regularly to keep the paint concentration. The pH value of the solution also need to be maintained at the proper value.
The electroplating finish for metal furniture
It is not suitable to do finish to the complex and big product. The big object will need a big tank of paint solution that may be very very expensive. It also cannot make a complex and artistic finish. It is more suitable to do finishing process for the similar product and with big volume. The simple form products such as the filing cabinet for office furniture, leg or other component part are the suitable product.