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Cadmium plating over aluminum and aluminum die casting using electroless as undercoat

2007

Q. Dear Sir,

I read your site it is very interesting.I have some question for regarding my plating line hope you will throw some light on it. Myself Mr. kamlesh M.Bhatt. Having 20 years exp. in electroplating.We are in the field of manufacturing connecters in India Company as Amphenol Interconnect India Pvt. Ltd.

I want to know cleaning cycle over aluminum & aluminum die castings for Electroless Nickel plating as undercoat & cadmium plating as overcoat followed by olive green passivation.Aluminum die casting used of 6061 grade & aluminum used of 7075 T-6 .We are facing Blistering problem.

Please suggest cleaning cycle for both the processes.

Regards,

K.M.Bhatt.

Dy. MANAGER.

KAMLESH M.BHATT.
Manufacturing all types of connecters.r - PUNE, MAHARASTRA, India

A. Hi Kamlesh. Rather than asking people to describe perfect plating cycles (which may not exist, and which are better described in books than public forums anyway, and which may be impractical for you to install considering the realities of your parts, their shape, your existing installation, and available floor space), please try to tell us the cycle that you use and where the blisters seems to occur. Then people can hopefully narrow down from a hundred broad possibilities to some tenable solutions. Thanks.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

2007

Q. Cleaning cycle degreasing T-C-E -10-15 MIN SOAK CLEAN: sodium carbonate / washing soda [affil links] - 30-35 G/L 2 MIN.; trisodium phosphate [on eBay or Amazon]30-35 G/L; TEEPOL 2-3 ML/L
RINSE PLAIN WATER 30 SEC -1 MIN
DESMUTTING: NITRIC ACID 95 % 1.5-2 MIN; HYDROFLUORIC ACID 5 %
RINSE PLAIN WATER 30 SEC-1 MIN.
ZINCATING ALBOND DIP ( CMP ) 100 % 1-1.5MIN
RINSE PLAIN WATER 30SEC-1 MIN.
NITRIC ACID NITRIC ACID 80 % 1 MIN.
RINSE PLAIN WATER 30SEC. -1 MIN
DESMUTTING: NITRIC ACID 95 % 1.0-1.5 MIN; HYDROFLUORIC ACID 5 %
RINSE PLAIN WATER 30 SEC-1 MIN.
ZINCATING ALBOND DIP ( CMP ) 100 % 20-30 SEC
RINSE PLAIN WATER 30 SEC- 1 MIN
E. NICKEL (MID PHOS) ATOTECH 15-20 MIN 2.5-3 MIC
RINSE PLAIN WATER 30 SEC-1 MIN.
CADMIUM PLATING: METAL:25 G/L T.CN :150 35- 40 MIN 10-12 MIC
RINSE PLAIN WATER 30SEC 1 MIN
O.5 % NITRIC NITRIC ACID 30 SEC.
OLIVE GREEN ATOTECH 30 35 SEC.
DRY 5 MIN
OVEN TEST 150 DEGREE 1 HR.

BLISTERS OBSERVED IN KNURLING AREA & FLANGE IN CASTING WHERE DARK CASTING MARKS INSIDE MOSTLY BLISTER SIZE IS MICRO ONLY CAN BE SEEN IN 10 X MAGNIFICATION.

PL. SPECIFY ANY PROCEDURE OR SPEC FOR CHECKING CADMIUM PLATED PARTS.

THANKS,

K.M.BHATT.

Kamlesh
- Pune, Maharastra, INDIA

A. If I read the verbal description correctly, the problem appears to be in recessed areas like the knurled area. So I would strongly suspect the cleaning cycle.

I think what I would do is to scrub a number of parts with pumice [on eBay or Amazon] and a tampico brush before starting the cleaning cycle, and monitor whether this improved cleaning solves the problem. If it does, perhaps an improved proprietary soak cleaner will be a good production tool. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

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