ZINC ELECTROPLATING ON ID OF TUBULAR COMPONENTS

[rknjs]

Dears

We have a product of size 320mm long and ID 80mm , which requires to be zinc electroplated as per ASTM B633 TYP 3.But at the time of electroplating we observed that the ID portions are not getting zinc depositions and hence parts are getting rejected on coating.Can anyone pls advise how we can process zinc plating on ID area.We are doing plating by hanging the parts in the bath(vat plating) with air supplied into the bath to ensure flow.

 

[moltenmetal]

I don't know a thing about electroplating, but the process seems simple enough. You have decent mixing and hence you're not depleted in zinc ions inside the ID, so what else could it be? It must be current flow distribution- the liquid column is at least 1.6 m in length to the midpoint of the ID from each end, which is an awfully long conductor. A counter-electrode on the ID may be required to get sufficient current flow to have proper coating all the way into the ID.

 

[Compositepro]

You need to run a wire through the tubing and keep it centralized to act as an electrode inside the tube.

 

[MikeHalloran]

I'm not convinced that 'a wire' will do as an electrode.

You may have to hang a round zinc bar in the center of each tube, and connect those bars as the counter-electrodes.



Mike Halloran
Pembroke Pines, FL, USA

 

[dik]

The DC charge will 'push' the charge from the inside to the outside, the same way voltage is only on the outside surface of a wire. Also Van de Graff (sp?) generator has a 'dome' and the charge concentrates on the outside.

Dik