The hanger for plastic electroplating should be able to fix the plated parts, ensure conductivity, and install necessary auxiliary anodes and shielding shields. The hook part is made of copper to ensure good conduction. If the passing current is large or the parts are unstable, it must be equipped with screw clamping. The path through which the current passes must be able to withstand the amount of electricity passed without causing heat, so copper can roughly withstand 2A/mm2, aluminum 1.5A/mm2, and steel can only be 1A/mm2. The contact between the hanger and the part should be tight to prevent excessive resistance If it is too large and generates heat, the contact area should not be too large, otherwise contacts and underplating spots will be revealed on the plating layer. In order to reduce or eliminate such imprints and ensure the completeness and uniformity of the coating, the contact points should be easily replaced during the plastic electroplating process. The hanger should not be too cumbersome, and the hanger of the crane should be equipped with a hook.
The most common problem encountered when placing more than one plated part on the hanger is uneven current distribution. The plating parts should be buried 50mm below the liquid surface of the plating tank and not less than 200mm from the bottom of the tank. There should be no additional obstruction to the current path between the cathode and anode. Except for the conductive areas such as hooks, the hanger must be coated with a protective layer or wrapped with plastic tape to avoid current dispersion and unnecessary loss. If there is coating accumulation, it must be removed in time. The arrangement of the parts should not interfere with each other, and the gas in the cavity and hole can be discharged smoothly. Lax bandaging and retention of plating solution will cause cross contamination between plating tanks.
The auxiliary anode or baffle used to promote uniform current distribution should be able to be directly fixed on the hanger, or be installed in other ways to ensure that the position is suitable and does not change randomly. Regardless of the arrangement, the relative position between it and the plated parts must be determined after calibration according to the test results. The interference of racks and plating parts is often due to excessive loading in the plating tank. Excessive loading of plating parts makes the plating solution unable to stabilize and the plating thickness between the parts cannot be guaranteed to be balanced. At the same time, the convection, stirring and heating and heat preservation of the plating solution cannot be guaranteed to be normal.
The success or failure of local insulation work is closely related to the type of electroplating solution, dispersion ability, surface tension and corrosion; it is also related to the material of the part, the location of the insulation requirement, the surface finish and corrosion resistance, etc., so it cannot be generally affirmed. Which method can solve all problems. It is one thing to partially block the coating so that the coating cannot be deposited, but whether the edge junction can meet the standard and whether the parts are easily corroded is another matter. So in practice this kind of work must be treated differently and acted cautiously.