Chromium plating in the inner hole is often encountered in hard chrome plating, and local unplated layers are also common due to electrical conductivity or anode problems. In the repair process, how to deal with the iron matrix and chromium layer, and the joints can not have steps, to ensure that the plating of the binding force is the key to repair. The repair steps are as follows:
1) Grinding and polishing. If the part is large, the inner circle can be polished conditionally, and the boundary between the chrome plating layer and the non-chromium layer can be eliminated. If the part is small, it cannot be mechanically polished, sanding or oilstone can be used to make a smooth transition and then measured. Good inner hole size, calculate plating time, enter the next process.
2) Degreasing. First scrub the surface of the inner hole with gasoline, scrub it with chemical degreasing soaking, and then use hot water to rinse the contents of the hole.
3) Rinse the inner hole with tap water and flush any residue in the hole.
4) Warm up. Put the parts on a good rack, do a good cathodic protection, put it into the plating tank and preheat it. The warm-up time depends on the part size.
5) Plating. First reverse plating with 20A/dm2 current l0 ~ 20s, and then transferred to positive plating. Stepped power supply during positive plating and normal current in 15 minutes