The authoritative public forum
  for Metal Finishing 1989-2024
  

  -----

Complete setup of an electroforming system

2007

Hello,
We have been doing standard electrolysis applications until recently. But we decided to bring electroforming tech. to our place. I will write down the chemicals and the system we use in an another topic . But firstly , I would like to ask you the proper set of an electroforming system. This is a very basic question. But I am really new at this and I need starting point. I would be glad if you see my weak position and short time, and help me..

Thank you.

Özüm Safaoglu
student - Ankara, Turkey

---

Please explain the electrolysis applications that you presently do, and then we can extend things into electroforming by explaining what would be different, Ozum. In principle, the only difference is that the plated layer itself becomes the object in question. This in turn implies that the plating has to be thick enough to be functional as an independent object, and that the mandrel upon which it is formed must be removable in some way. The mandrel might be wax (melted away), aluminum (dissolved away), stainless steel (mechanically separated). If the mandrel is stainless, it usually needs to be cleaned and passivated before each use, and then it is electroplated.


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

---

2007

Thanks for response. I am sorry for my undetailed question. We have been doing photo-electroforming in order to produce logos and nameplates-inlets. In order to provide a bright surface finish we have been using a Nickel Sulphate bath. Here it is :

304 g/L Nickel Sulphate
45 g/L Boric Acid
55 g/L Nickel Chloride ( NiCl.sub.2)
8,5 - 9 A/dm2 , 4,5 V
Operating Variables :

pH: 4.2
Temperature : 55 C

We are producing flat letters like 40-50 micron(We are coating the mandrel with photoresist then expose it to UV light to reveal image, then we deposit nickel into the mandrel surface which has not have photoresist on it) . But the metal distribution is not good. Edges are more thick than middle places. I don't know how to gauge internal stress. Also I don't know if it is because edges drain more Amperes or it is because internal stress is too high. Can internal stress cause a problem like this? If it can , compressive stress or tensile stress ?
As you can notice I am really confused. I am an university student and not really experienced. But I have learnt a lot of things recently. Sometimes I may have troubles with combining things. But now we have this main problem of thicker edges. I had a look at foreign firm's patterns. Their products almost have circle shaped edges. They look perfect. I don't know which additives to take good products like that .
In conclusion , I need help about this thicker edges problem. I would appreciate this if you helped.

Also,
I have been working on Electroforming by using watts solution. Watts solution provides bright surface while I am trying to produce flat letters. Can I use sulphamate to provide bright surfaces ? I am having trouble with thicker edges. So I tend to change my solution with sulphamate.. If I can not provide what I want with sulphamate (it is expensive also ) what can I do with sulphate in order to prevent edges lifting more then middle?

Thank you.

Özüm Safaoglu
Student - Ankara , Turkey

---

2007
Nickel sulphamate is the usual thing for electroforming, Ozum. The sulphamate radical supports a higher concentration of metal than sulphate for faster plating, and it produces a lower stress deposit which is crucial in an electroform. A spirit of learning is to be highly admired, and we appreciate your efforts as a student! So I am not saying that you should not experiment with electroforming from sulphate, just helping you understand what the advantages of sulphamate are, and why it is usually used.

There are a variety of devices for monitoring stress. Industrial Instruments and Specialty Testing & Development have devices that will help you. Another stress testing item called "Stress Tabs" may help too. This is a hull cell panel which is painted only on one side and serrated to look like a comb, with the result that the tines will bend up or back to reveal the stress at varying current density.

While brighteners and addition agents can have some effect on variations in plating thickness, the primary approach probably must be to use shields (plastic stencils that allow current to flow through only in certain areas, forcing the current to take "the long way" to edges and corners.

Please recognize that many people have spent their entire professional lives in nickel electroforming, so it is not a matter of a quick check list of what you should do to optimize your electroforming. Thus, while you should be learning as quickly and effectively as you can, if your company has a crisis on its hand or this product launch is an urgent matter, ask them to call in a qualified expert rather than to be led by trial and error.

Good luck!


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

I couldn't get why you transferred me to other experts? You always answer questions. I wrote many questions in that post.The most crucial one was "Can I get bright surfaces with sulphamate solution". At least please answer 2-3 or three questions of me...

Özüm Safaoglu
Student - Ankara , Turkey
2007

Yes you can, Ozum. One way or the other. If you cannot get the desired brightness as plated, you can flat polish your sulphamate nickel electroformed letters. This will solve both problems. Brightness and flatness. You can also use a bright nickel topcoat over the sulphamate nickel surface but not for flatness only brightness. G. Marrufo-Mexico

Guillermo Marrufo
Monterrey, NL, Mexico
2007

---

You need to measure stress if you are to control it and to prevent the edges from lifting. For that reason I suggested several manufacturers of stress measurement devices, Ozum. Also, the readers such as myself are in the dark about what you are doing; that's why I suggest that you work with a local consultant or supplier of plating chemistry.

Brightness is relative, but sulphamate does not offer the brightness of bright nickel plating from a Watts' bath. Guillermo has answered your question about how to electroform with sulphamate nickel yet get top brightness.

As for "transferring you to other experts", Ozum, I am not an expert at electroforming, just someone who has some book learning and a small amount of actual experience. Plus, if you want to learn to fly an airplane, it is fine to read about it, but at some point someone should personally be with you in the cockpit. Without actually being there and seeing the setup, there comes a point at which I can't help much further. Sorry.

Good luck.

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

If the surface at the bottom is matte, wouldn't the surface at the top be matte too even it was plated with sulphate solution?

Özüm Safaoglu
- Turkey
2007

---

Not necessarily, Ozum. The surface at the bottom will exactly match the mandrel; the surface at the top is free to be responsive to the influence of brighteners. If you have the opportunity to see a plating "blister", you may find that it is rather matte on the underside, and bright on the topside. Letters 29693 and 35945 include photographs showing that effect.

Bright nickel plating solutions are usually based on nickel sulphate / nickel chloride "Watts" baths with a brightening agent. These baths "self level" and can give a bright finish, such as is done with nickel-chrome plated truck bumpers. Good luck.

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

---

September 6, 2008

Hello Ozum ... I think you perfected your process of forming letters.. I am also manufacturing similar parts but am having problems in removal of parts...

1. I would like to know the what photoresist ink are you using..

2. in which apparatus do you develop your plates...

3. what material are you using as mandrel ....

4. what stress reducing agent can be used in bright nickel

5. the adhesion between mandrel and the product formed is very high and how can I reduce it ...

Shobhit

help please

Shobhit Tuteja
- Delhi

The reason than the alphabet letters are thick at the edges is as there is no friction in the mandrel surface so as they are being formed they release from the surface

Amit Jain
- Delhi, India
December 6, 2008

---

hi, about your problems about edges:

I'm student too, and I don't have experimental information. but as I know about theoretical knowledge, you can use two cathodes. first your mandrel and the second is another metal that its shape is complex. for example, if your mandrel is cubic with low thickness,your second cathode should be like a frame with that dimensions. you know,theory is this: where you have edges or spots, the current density is high there. so there becomes thick after electroforming. so you should decrease current density or nickel concentration around there to make the electroform thickness uniform.if you use a second cathode around that edge,it use your nickel ions around edge and make its concentration low there.so your mandrel's uniformity improves.you should use two sources and the voltage of both cathodes should be same.their distance should be around ten cm.

Majid Mazhar
msc student - Tehran, Iran
June 18, 2010