Plating on Leaded Parts
We have to plate leaded steels with zinc. Can you give me a procedure that will work for such substrates?
Q. We have to plate leaded steels with zinc. Can you give me a procedure that will work for such substrates? E. A.
A. This is a problem that platers continually seem to struggle with. I have addressed this issue a number of times in the last 11 years and the answer does not change. Here is what I wrote in one of my earlier columns:
The lead (0.15–0.35% by weight) is added to the steel to improve its machinability. Lead smears on the part surface during machining and tends to act as a lubricant. Use of “standard” cleaning cycles does not remove all of this lead. The following cleaning cycle should remove the lead and give you a good clean surface for your electroless nickel plating.
- 1Soak clean.
- Clean anodically at a current density of 90–100 ASF in a strong alkaline cleaner.
- Dip in an acid such as acetic, fluorboric, glycolic or citric acid.
- Rinse well between each step.
- Proceed to your zinc plating step(s).
Proprietary acids are also available. Look in the PRODUCTS FINISHING DIRECTORY & TECHNOLOGY GUIDE under Cleaning Chemicals, Aqueous for names of vendors or do a search on www.pfonline.com in the suppliers database.
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