Ask the Expert Question-and-Answer Archive
(Hard Chrome Plating)
by Randy Taylor, Advanced Tooling Corporation
Electroless Nickel-Phosphorus Plating Thickness Variation Range
Q. I have requested application of Electroless Nickel-Phosphorus Plating to a couple of aluminum hosings. These housings have quite complicated geometries, my question is how much plating thickness variation can I expect? Does variation increases with larger thicknesses? Lastly, is there a site in which a typical process is explained. I am interested on sample preparation and typical problems. Thanks!
A. Electroless nickel coatings on aluminum are successfully done all the time. Success depends on using an experienced E-nickel plating shop. You'll want to distinguish whether or not the vendor is knowledgeable of coating aluminum and are plating aluminum on a regular basis.
From your comments, the part sounds a bit more complicated, but as long as the necessary pre-treatment steps are performed well and bath chemistry is good, there's no reason you should expect trouble. If the part has a difficult geometry, your plating vendor may be required to make a special holding tool or rack frame to suspend the part into the various baths and to aid in thorough rinsing between steps. It may be necessary to turn or manipulate the part in order to minimize air pockets or purge blind holes.
All things being equal, you should expect no noticeable variation in nickel thickness on surfaces that are fully engaged with the nickel plating solution for the correct amount of time. This applies up to about 0.003 thick. Typically E-nickel coatings above 0.003 thick begin to distort and sharp corners may become rounded.
Variations in bath chemistry, in particular phosphorus content in the nickel, can affect the deposit rate and coating performance. Your plating vendor should be able to provide you with this and other technical information, physical characteristics and properties of the nickel deposit as well as recommend the best plating bath for your part. There are a wide variety of good E-nickel shops out there, shop around.
For even more information on E-nickel (electroless nickel) contact Plating Process Systems, Inc. 7561 Tyler Blvd., Suite #5, Mentor, Ohio 44060, phone number (440)951-9667. Ask for Mark Schario or John Salyards - firstname.lastname@example.org , MarkS@platingprocess.com
I hope this helps,
Best of luck, Randy Taylor