How to determine the anode area when the cylindrical workpiece is coated with the cavity?

When plating cylindrical workpieces, a combined cathode and anode hanger must be used. This can fix the position between the cathode and anode, avoid short-circuit and burn the workpiece, and maximize Increase the effective area of ​​the anode to the limit. Increasing the anode area can prevent trivalent chromium from accumulating too quickly for chromium plating parts, and for other plating species, it can also prevent passivation due to excessive anode current density and make The cathode current density is difficult to meet the process requirements, and the quality of the coating cannot be guaranteed.

The anode area should not be too small, but the anode area should not be too large when plating this kind of workpiece, otherwise the distance between the cathode and the anode is too close, and the gas is difficult to discharge freely during electroplating. In order to prevent such accidents, the following measures can be taken: make the anode hollow and vent holes. This method can increase the anode area by more than one-fold under the same conditions, and the effect is significant, as shown in Figure 2-3.

Using this kind of combined hanger can also avoid to a certain extent the uniformity of the coating thickness due to exhaust problems, but if the diameter of the lower section of the anode is slightly larger than the diameter of the upper section, the effect will be better.

The device shown in Figure 2-3 is most suitable for cyanide zinc plating or zincate zinc plating for the inner cavity of tubular parts. The anode can be made of iron pipe with corresponding outer diameter.

Other plating types need to use corresponding anode materials.