Cathodic electrophoretic coating has many advantages, such as uniform coating film and strong adhesion, which can simplify or eliminate conventional electroplating processes, reduce production costs, shorten operation time, increase productivity, and realize automated mass production; good swimming penetration, coating film The coating has good corrosion resistance; the color of the coating is bright, and the use of different pigments and ratios can be used to obtain various color coatings; the appearance of the coating film is good, and it has good flatness and ductility during drying; closed circuit Circulating ultrafiltration device and ultrafiltrate purifier, the utilization rate of paint can reach more than 98%; especially, the paint does not contain toxic and heavy metal ions, and the discharged water almost does not need to be treated, which is beneficial to environmental protection and is a low pollution coating One of the new methods.

In view of the above advantages, cathodic electrophoretic coating has been rapidly developed in the field of metal surface treatment at home and abroad, and domestic small and medium-sized manual cathodic electrophoretic paint production lines have been continuously launched. However, some manufacturers are unable to form continuous, large-scale and stable production due to lack of technical management experience. The author summarized the work experience in the past 6 years for readers' reference.

At present, the products processed by the manual cathodic electrophoretic paint production line are mainly fishing gear, bicycles, motorcycles and various daily hardware accessories. The product features are: large number of workpieces and small surface area. Practice has shown that in the electrophoretic coating process, the design and manufacture of the hanger is very important, which directly affects the production efficiency. The following points should be paid attention to when designing, manufacturing and using electrophoretic coating hangers.

Electrical contact between the hanger and the workpiece

The hanger is treated with electrophoretic paint, and its hook is insulated by covering it with electrophoretic paint. The cathodic electrophoresis process uses high voltage and low current. Practice has shown that as long as there is a "point of needle" contact point between the workpiece and the hook, the electrical conductivity requirement can be met. At present, some manufacturers directly hang the workpiece on the hanger, and the workpiece shakes back and forth during production. It is easy to collide, and the hanger needs to be painted after each electrophoresis. The cost increases and the production efficiency is not high. Research has determined that the hook part is made of spring steel wire. The shape of the hook can be flexibly selected according to the product type. One strand adopts a three-point or four-point contact form. The tip of the hook is better to maintain a 45° bevel when cutting. When hanging the workpiece, turn the workpiece back and forth to make the electrophoretic paint on the tip of the hook. The layer is scratched, so that the paint removal treatment of the hanger can be avoided, the workpiece is ensured to be fully conductive, the cost is reduced, and the production efficiency is improved.

Fixing of the hook

At present, some manufacturers use brazing or soldering to assemble the hanger, which has the following defects: ①The melting point of copper is 1083℃. When brazing is used, the spring hook is annealed and loses its elasticity and cannot meet the production requirements; ②The cathodic electrophoretic paint The drying temperature is generally above 160°C. The tin becomes brittle tin when heated to 160°C, which is easily crushed. Using tin-welded hangers, the hook will fall off after working for a period of time.

Our factory uses mechanical assembly method to assemble the hanger. It has been used for more than 3 years without any damage, which reduces the production cost and improves the production efficiency.

Cleaning of hanger

For workpieces with complex shapes and blind holes, in order to make the solution in the blind holes clean and recover, there are handles on the top and bottom of the hanger, and the front and back are cleaned twice. Not only can the workpiece be thoroughly cleaned, but also the paint adhered to can be removed. The floating paint on the surface of the film prevents the paint film from being painted.