Letter 36050

Chrome Bath Content  

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I am a new engineer in an injection molding facility. We hard chrome plate our molds. I am new to hard chrome plating so I may be asking very basic questions so please bear with me.

We have a set procedure to check for chromic acid content in the chromic acid bath. Many believe here that we are not following the procedure correctly or the procedure may be incorrect. Can you give me some guidelines/procedures/help with the proper way to check for the chromic acid content? Also, checking for sulfates? And, if the chromic acid level is measured low, is it as simple as adding a prescribed amount?

The main reason I am asking is that recently our chrome coating seems to wear away quite a bit faster than in previous months/years. No one seems to know why so I'm trying to start with the bath contents and work my way forward.

Again, I know these are pretty basic. But any help or links to help will be greatly appreciated!

William Belanger
Injection Mold Plating - Morristown, TN

Hello William; welcome. But please tell us what your procedure is rather than asking us to guess whether it's good or poor, sight unseen. We have no idea what analysis equipment and capability you have, so for us to suggest an AA test if you don't have one isn't helpful, nor is it helpful to assume you can only do the lowest tech tests possible. Instead, tell us what you do and let's talk about that. I don't think I'd start with the chemical analysis anyway, though; I'd probably start by finding out what the specified thickness and the actual thickness are.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

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