Plating diamond grit on tools

A. Hi Akshay. I can't offer much help but I do think you are misunderstanding. To my knowledge, "glueing" or "tacking" or "resin bonding" the diamond to the wheel is for the most part an old-fashioned -- and generally regarded as inferior -- alternative to plating them on, although Jeffrey Holmes knows of tacking large diamonds in place before plating. Plating them occludes them into the nickel deposit so they're really stuck on good :-)

Luck & Regards,

A. Hi Brian, Hi Manmohan.
General Electric offered electroless nickel plated diamond particles at one time. They might still offer them, or another company may, or you may find an expired patent on how to do this.

But if you are trying to encapsulate the diamonds into a nickel matrix, I don't think that it's necessary to make them conductive first. I think you just plate and let the diamond particles be occluded into the plating.

The principle is fairly easy, but the execution is not. Diamond particles are suspended in an electroless nickel, electrolytic nickel, or chrome plating solution in a fluidized bed, possibly with the assistance of thixotropic addition agents. With the proper dispersing agents, when the plating occurs, the diamond particles are occluded into the deposit.

There are a number of energetically enforced patents in this technology though, and what isn't patented is held as trade secret. So the fastest entry into the technology, and perhaps the best, is to license it. Good luck!

A. First of all do a world wide patent search. The technology for composite coating with diamond is well established. There are two basic ways of doing it. The first is to hold the diamond particles in suspension by agitating the electrolyte and have the workpiece at the bottom of the tank, where it is being coated in nickel. By controlling the rate of settling of the particles, you can alter the percentage diamond in the composite. Secondly, you need to use a good surfactant that will keep the diamond particles in a suitably charged solvent sheath. This will make the particle act like a cation and it will be co-deposited with the nickel. In both cases the practice is harder than the theory!

A. Your posting presents little information about your process, Mr. Patel, and more information would be needed in order to make the most helpful suggestions. We don't know your electrolyte, or the temperature or volume of the bath, or the plating time, or the surface area of the parts you are plating. Does the pH nosedive early on and then hold steady, or does it gradually decline as you sequentially plate hundreds of pieces?

Regarding the second question, you can buy diamond powder that is already nickel plated if you wish to see if that helps, but generally you need to keep the diamond dust in suspension to be occluded into the deposit; and that may involve designing a fluidized bed instead of simple agitation, and/or adding thixotropic agents to the process. The technology is licensable if you wish to go that way. Good luck!

A. Getting diamond to co-deposit is not easy. You need a very good way to keep them in suspension. This might be a pumper plate or it might be a pump that picks up off of an inclined tank bottom and puts out the suspension in a uniform manner at the top of the tank. The diamonds might need to be periodically treated with peroxide to remove an organic slime from the surface that will reduce the co deposition. Deposition is temperature and current density dependent. It may require a special wetting agent. Specifics are very proprietary and I doubt seriously if any one is going to give you very much in specifics. The people that develop these process have zero need to share information that will eventually hurt their business growth.

A. There are numerous issues concerning nickel/diamond co-deposition. The first one is to get the diamond particles of the required size; this is down to your supplier. secondly, you need to get them wetted, so you need a suitable surfactant. A lot of work was done in the 1970's and 80's related to this, but it was wrapped up in patents. These patents have now expired and the technical side of the science is available in the technical literature.

The next problem is to get the diamond to deposit onto the cathode in the required manner. Since it is not highly charged, this is a significant problem, but one neat way I have seen is to let gravity do the job. This requires the cathode to be horizontal and on the base of the plating tank. If necessary, it can be rotated in the horizontal plane. The electrolyte is agitated from the base of the tank, thereby creating a gentle up-flow. This will help keep the diamond in suspension and will control the rate at which it falls onto the cathode. You then need to balance the deposition rate of the diamond with that of the nickel, so you get the correct composite composition. Good luck.

A. I have seen this done, using a tiny bit of adhesive (epoxy?) to secure the individual diamonds in the desired pattern before nickel plating to lock them into place. I believe it is done with only large diamonds (> 0.1 carat?).

A. Surely a better way is to use the correct surfactant that will allow the diamond surface to become receptive to aqueous nickel, thereby forming a better bond between the diamond surface and the nickel? The "art" in creating composites is to have good surface interactions between the electrodepositing metal and the material being entrapped. Glue will not offer this as well as direct entrapment will.

? If it is a secret how this is to be used, no one can help you. If not, what it the final product used for, and why is diamond necessary if it is not obvious to most of us.

? Maybe if you were more specific someone could give you an idea. What size is (or are) the particle(s), what shape, what conditions, but most important, what for? I can think of single piece large and sharp diamonds used to dress grinding wheels, also jewelry files coated with numerous tiny diamond particles or parts designed for extreme abrasion against delicate materials plated with microscopic rounded synthetic diamond embedded in metallic matrixes.

A. Hi. I could be reading wrong, but it sounds to me like Vipul is asking how people get diamond particles to adhere to steel for use in grinding wheels ... and the short answer is that the steel is electrolessly plated or electroplated with a nickel solution which contains diamond particles, and the diamond are occluded and incorporated into the nickel plating: the nickel plating has outstanding adhesion to the steel and the diamonds can't fall out because the nickel plating encapsulates them.

Regards,

A. Put the diamond dust in the sulfamate nickel plating solution and keep it suspended with vigorous agitation. With some experimentation you will find the right parameters to occlude the diamond dust in the electroplated nickel deposit. It does not "electroplate", the diamond dust merely "occludes".

A. Having just seen Will Smith's "The Pursuit of Happyness", I'm not going to tell you that you can't do it, Dan :-)

But I will tell you that it will likely be faster, easier, cheaper, and you'll get a much better product by having it done by a jobshop that specializes in it. If you do it with Electroless Nickel rather nickel plating, it can be heat treated.

Try to make sure that what you do is not covered by patent as the patents in this particular field are very aggressively defended. Good luck.

A. Hi, Mary Jane. Is there a reason why my suggestion of contracting the work to a plating shop isn't satisfactory. Perhaps you are a plating shop yourself?

You can google for "composite diamond electroless nickel" or "composite diamond nickel plating" and license the process from the suppliers who have developed it if you wish; that way you'll be told everything about it in exchange for keeping it confidential and paying a license fee.

You won't see the details fully shared because people still regard them as proprietary trade secrets, and because some of the people who are doing it apparently fear that they might be violating patents. In this particular field the patents are very aggressively defended, so even if people aren't violating them, they tend to keep a low profile.

In general, though, you do composite plating like this by keeping the diamond particles in suspension. Designing a fluidized bed under the cathode would seem to be one way to do that; surfactants for wetting the diamond particles, and dispersing agents in the bath are probably important; I have also been told that thixotropic agents like barium sulphate or fumed silica are sometimes added to the baths. The diamond particles can cause severe stability problems in an autocatalytic process like electroless nickel, so the bath has to be adjusted to prevent spontaneous plate-out. I myself have been curious about some of the details for years.

The technical article "The Environmental Benefits of Composite Electroless Nickel Coatings" will tell you some things, but again, the author is licensing the technology and is careful to not tell you enough to be able to do it. But follow the patents he has cited and you'll learn more. Good luck!

Regards,

A. Hi Ray. The fastest way into the business would be to contact Surface Technology Inc. (STI) in Ewing, NJ who developed and introduced most of the technologies. My understanding is that they license the technology rather than consult on it, but that would be a discussion between you and them. Good luck.

Regards,

? Hi Ray. Sorry, I can't interpret what went on in e-mails between you and them, and why they were/seemed uninterested in your custom. I suppose it's possible that they felt that you would not be a big enough customer to warrant a licensing arrangement and they don't want to risk revealing their technologies to small customers, or perhaps they feel occluding diamond grit onto tooling with nickel plating was too common for them, and they only want to be involved with the electroless method anymore ... sorry, there is no way I can say.

Regards,

Ummm, well, Ted,

I have been in the largest nickel encapsulated diamond facility in the country.

While I cannot reveal what I know about their technology, suffice to say it is far more sophisticated than simply keeping the diamond in solution.

It is, as they say, a very sophisticated process.

Hi Jeffrey. Sorry if you feel I implied that electroplating of diamonds is easy; I was trying to say that perhaps it is common enough that vendors either don't find it feasible to license their technology to small producers anymore or prefer to steer them in the electroless direction.

As a plating consultant and expert witness for decades, I recognized that the patents & trade secrets in composite diamond plating were extremely aggressively defended -- far more so than any other metal finishing field that I knew of -- so I actually worked hard to avoid learning anything about it except what is published to avoid being pulled into those suits myself :-)

I knew Nate Feldstein, the best known developer of this technology, as well as his son Michael, and visited their shop, Surface Technology, a couple of times, and met with Michael several more times. We avoided discussing the technology, and although I've also been tank-side at tooling manufacturers who made electroplated nickel-diamond grinding wheels a couple of times, I've been very careful to never get involved in the deposition of diamond grit :-)

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 2017

  Hi Krishan. Maybe, maybe not, depending on whether the issue is a generic electroplating one. Was your use of the word "electrocoat", which is strongly associated with organic coating, deliberate?

Regards,

A. Hi Krishan. I may be misunderstanding you, but it sounds like you are using an old-fashioned technique of gluing the diamonds in place via electrocoating, and then electroplating. The accepted modern method, I believe, is to have the diamonds suspended in the plating solution for superior adhesion. As I have said earlier on the page, I very deliberately don't know much about composite diamond electroplating and electroless plating :-)

Regards,

? Hi Paul. Your question is quite cryptic. Is your reference to ferric chloride perhaps suggesting the possibility of occluding diamonds into electrodeposition of iron rather than into electrodeposition of nickel? Thanks.

Regards,

? Hi Matteo. In my ignorance I am wondering why old baths are discarded and new ones made up. I've known nickel plating baths to be used for many decades :-)

Regards,

A. Hi Nicholson.

1. As you can see from reading this page, I'm not going to comment on the first question.
2. Bright nickel plating operates at about 40 Amps/sq.ft. (4 Amps/sq.dm.)
3. I think you would need to plate the whole rod first, and the diamond area subsequently (otherwise nickel plating would build up over the diamonds. The diamonds won't plate, but the nickel surrounding them will).
4. Bright nickel plating employs organic additives called "levelers, brighteners, and secondary brighteners".

Please tell us what you know already, such as: Have you done any plating? Are you an experienced nickel plater?

Regards,

A. Hi again. Clarifying point #3: The whole rod looks to me like it is plated. If it is, you probably do this before the diamond plating because the diamonds are occluded into a second layer of nickel plating. If you do the overall plating last, rather than first, the nickel surrounding the occluded diamonds will grow and cover some of the diamond.

No one is going to freely give you "the total solution" of how you wet the diamonds, how you get them to remain in solution, and how you get them to be occluded onto the shaft, because it is still trade secret; and if they did, we couldn't post it anyway because we can't risk abetting the crowd sourcing of industrial espionage.

While nickel plating is generic knowledge found in technical articles and plating textbooks, pieces of this are not yet generic knowledge: you either pay someone for their knowledge of it or you experiment and develop the knowledge for yourself. If your vendor is able to do this in a very small place in his home, it sounds like he has excellent know-how that you might consider buying from him rather than spending months or years trying to learn for yourself. Best of luck.

Regards,

A. Hello Nicholson,

We manufacture tools similar to the one you showed in the picture.

Technology is not sophisticated: we use a standard sulphate bath! We just use the right current and time to have a good mixture of nickel and diamond.

I agree with Ted on one point.
This kind of production has no big margins.
If you buy tools for hundreds of thousands of dollars, then you may consider producing them.

Otherwise you will be loosing money.
Most of our costs are fixed costs (personnel, environment, etc.)

Hope this helps you.

Best regards,

Matteo

 Thanks for your inputs Mr.Ted and Mr.Moozi, based on the above explanations, I will proceed further. But I still do want to give a try for above mentioned type of plating.

A. Dear Nicholson,

I would amend your procedure as follows :

Step 0: accurate degreasing
Step 2: Use a Masking lacquer to and mask the areas which is not required for plating
Step 1: Surface preparation. We normally use sulfuric acid.
Step 3: Electrolytic nickel-plating, in a Wood bath, of the surface so activated
Step 4: Application of a powdered-diamond coating to the surface nickel-plated in stage 3, by application of a second electrolytic nickel-plating process in a Watts bath where powdered diamond is in contact with the cutters
Step 5: Stabilization of the powdered diamond by a third electrolytic nickel-plating process in a Watts bath
Step 6: de-masking
Step 7: aesthetic nickel plating

Use current densities below 0,5 A/dm2

Hope this helps you!

Best regards.