The authoritative public forum
  for Metal Finishing since 1989
-----

Zinc nickel reel to reel plating

I would like to plate zinc/nickel in a alkaline bath (for reduced surface stress and good formability) on wire in a reel to reel system is there a bath with a high enough current density to be effective. Is it possible to plate in a reel to reel system with a alkaline bath? What chemistry will do this?

Harvey P [last name deleted for privacy by Editor]
- Bedford Hts., Ohio
2003

---

I'm not sure about that, but if good formability is required, I would think you would be much better off with a soft plating like tin-zinc.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

---

Ted,

Thanks for your help with our plating project. Let me give you some basic specification for the plating. We are seeking a sacrificial corrosion protection coating that will be used on high carbon steel wire (AISI 1070) of .036 square mean size (size range .015 to .047). It must have a thickness of .000150Ÿ, pass an ASTM 50 hr. salt spray test to red rust. Also be able to be wound into a tight index coil spring (similar to winding on .125 arbor) without flaking off due to brittleness or gouging the plated surface from the mechanics of the coiling machine (we have to develop a Vickers Hardness # for spec.). We have tried zinc sulphate bath plating and it is too soft and gouges off during spring coiling. We have been successful with an Alkaline Zinc Nickel bath (5 to 8% Ni) that was rack plated. The goal is to be able to plate the wire in a reel to reel system @ a minimum of 500 fpm and have an acceptable product.

Harvey P [last name deleted for privacy by Editor]
- Bedford Hts., Ohio, USA
2003

---

I don't exactly understand your machinery, but if it gouges soft plating it will probably gouge tin-zinc, which is a soft malleable coating. If the alkaline zinc-nickel works when rack plated, I don't see why it should be any different when plated continuously on a wire plater.

I don't think 500 FPM expresses the problem in the significant units because the question is not how fast the wire is moving, but how much time you have to plate it. High speed plating of alloys is indeed problematical because the close anode to cathode spacing and extreme agitation will change the alloy balance compared to when it is rack plated. It certainly sounds doable, but exactly what adjustments you need to make to plate at high speed is hard to say without experimentation.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003