Plating Problem - 12L14 steel - Zinc per ES-1030 - Yellow chromate per ES-1100

[Connie]

Hi everyone!

I'm looking for some answers on a plating issue. Here is the scoop:

We have some shafts made with 12L14 steele which get plated with Zinc per ES-1030 and then coated with yellow chromate per ES-1100 at a thickness of .0004-.0006. The problem I am seeing is they are comming back with what looks like a chemical corrosion in spots. It looks like the metal actually was eaten away leaving pitting spots. the platers don't seem to have any idea why this is happening since they do not use that strong of chemicals.

Any Ideas!!!!

Connie

[M Greenaway]

Are you sure these pitting spots were not there on the unplated material ?

[Claes Gefvenberg]

Ok.. Some questions:

• Is this a new product, or have you done it before with better results? If so, has the process been changed?
• Is every part, or just the odd one affected? Difference between batches?
• Do you have any other similar products/processes that could have been affected, but are not?

And a few possibilities:

Are the parts really clean before the plating?
No residue from the cleaning?
Any chance of contamination in the plating process?

Let us know what it was when you find it, because find it you will... Good luck

Btw: I'm moving this thread to "Nonconformance and corrective action" I think we'll get more answers to it there.

/Claes

[Sam]

Although I couldn't find 12L14 in my "Jogensen" steel book; the "L" signifies a leaded barstock.
It is possible that the plating process is etching the material causing the pits.

[Connie]

Thanks for the reply on my question.
In answer; I'm pretty sure the pitting was not in the material. we have been machining these parts for over three years but we just switched to a different plating supplier. These are barrel plated if that makes any diffference. I'm not sure on their cleaning process we send the parts in oil to prevent rusting befor the plating operation. I have contacted the previous supplier they were unable to give me any answers either.

[Claes Gefvenberg]

Connie said:
---X---
we have been machining these parts for over three years but we just switched to a different plating supplier.
---X---

Aha... If that's when the problems started I'd follow that lead. Please let us know what you find.

/Claes

[CarolX]

Hi Connie and welcome to the Cove,

I am surprised that your plater won't give you an answer. My history with plating shops is they have at least one person on staff that knows all. I would try them again.

Or...what about sending it to an outside lab and have them analyze what it is.

Regards,
CarolX

Hi Connie,

I’ve been in the Metal Finishing Industries for over 10 yrs and it sound like your plater isn’t playing fair with you. Ask them what's in their cleaner and don’t they have an acid bath, most zinc plater do. It sound like they could be storing finished product near the production line, more specifically the tanks. Go for a surprise vendor visit, your parts may be getting splashed with product from the platers tanks. If it’s not in the metal, it may be from the barrel tumble the parts during processing that could be causing the dings or a pit in the shaft. My advice may have come to late but I would be glad to help you with your plating issues (e-mail me if you like), my feeling is that you are getting the run around from your plating sources. Keep in touch.