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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Electroless nickel plating inside blind holes
Q. Hi Guys
We are into coil winding and manufacture relay metal parts for relays. We have plating problem on the rectangular cores made of soft magnetic Iron . These cores have blind holes of dia 0.12 inches/2.7 mm and 0.250 inches deep, on two sides and are then tapped by using #6-32 UNC-2B. After annealing to below 10 Rockwell, plating process ENP is done.The Plating is approximately 2 to 4 microns.The core gets rusted when dipped in water for 15 minutes and viewed under microscope. The ENP does not reach the interiors near the threads because of air entrapped inside the blind holes.
Is there a solution to rectify this plating lapse.I would be great help if some one can help me to overcome this problem.
Best Regards
Buyer - Mumbai, Maharashtra, India
December 7, 2010
A. 1st, 2 microns of EN is not enough to "prevent" rust.
2nd, it requires an extreme amount of rack manipulation to get even some of the blind holes to plate. If the parts are not too big and too heavy, you may have better luck plating them in a barrel with heavy air agitation under the barrel.
Unfortunately, the part design did not consider plating.
- Navarre, Florida
December 7, 2010
December 16, 2010
A. To start with, ask your supplier to add a wetter to the solution.
Another solution which maybe less practical is to take out the parts from the EN every 3-5 minutes, tap on the rack and return it to the solution
Sara Michaeli
Tel-Aviv-Yafo, Israel
A. Another reason can be insufficient degreasing or pretreatment of the pieces. If you do not rinse the pieces well enough, it can happen that the holes will not receive the right amount of ENP.
A wetting agent is very easy to make, so there is no need to buy such a thing.
- Genk, Limburg, Belgium
January 12, 2011
Q. What is a wetter solution?
What is its chemical name ?
How does the wetter solution improve Electroless Nickel coverage in features with high diameter to bore depth ratio?
- Irvine, California
January 10, 2012
A. Hi, Laban.
A wetter solution is a surfactant that reduces surface tension. One such chemical is sodium lauryl sulphate. Wetter is not so much something you add to improve coverage in holes, as something you maintain for good plating. But one of the ways it may assist in plating in holes is by removing clinging hydrogen bubbles.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 10, 2012
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