Where theworld gathers for metal finishing
Q&As since 1989
-----
Plating problems on aluminum diecastings
Q. Could anyone kindly help me providing the composition of chromating solution for MAZAC(4% Al) ?
Thank you.
Stephen R [last name deleted for privacy by Editor]- New York, USA
2001
A. Hi, Stephen.
I honestly don't know any shops that formulate their own chromates; almost everybody uses proprietary formulations. If you are willing to do that, any of the plating process vendors will be able to offer a good chromate. These days you'll probably want to use a trivalent chromate so you can comply with RoHS requirements, and in that case a proprietary chromate will be a necessity. Best of luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 22, 2009
Q. We are one of the manufacturers of industrial products.
For our products we need various mechanical items. A few items are die cast, then plated.
At present we are procuring aluminium die cast items (it is called ZAMAK or MAZAC material). We do machining on the casting like grinding, tapping, etc. After that on the surface we do electrolytic bright nickel plating and on a few jobs nickel-chrome plating.
During all these processes we face following problems:
1) Plating aesthetic is not good
2) Plating dust is observed on the job
3) Plating quality is not consistent
4) Some small ball type structure is observed
Our main question is whether this type of plating is recommended on this type of casting? Or some additional treatment has to be applied on the surface before plating? Finally we require plating with ROHS compliance only.
Any pre heat treatment is required before doing plating?
We are facing this problem; we need firm solution.
buyer - Pune, Maharashtra, India
A. Hi, Anand. Some good news is that this material is very plateable and not particularly a problem. Heat treatment is not necessary. Also, it will not be a problem for the plating to comply with RoHS.
But the bad news is that electroplating is not drop-dead easy; there are whole books just on nickel and chrome plating, as well as books on inspection of die-castings for plateability. The host of problems you are encountering like poor brightness, star dusting or burning, entrapped particles from poor filtration, nodule growth, etc., is going to require some substantial on-site time by someone who knows electroplating very well.
Your plating process supplier should have competent tech service people who can advise you of the more obvious things that are not right; but you probably need to retain a plating consultant if you don't have knowledgable platers on staff. I apologize that this wasn't much help, but realistically it can take a plater with decades of experience a couple of weeks or a month to sort out this list of problems, and it's just not going to be possible for inexperienced personnel to fix it via internet postings. Best of luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 24, 2009
Q, A, or Comment on THIS thread -or- Start a NEW Thread