What You Need to Know About Electroplating, and When to ...

Originally published on fastradius.com on October 28,

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Most consumers don&#;t think about the surface finishes of their favorite products, but post-processing is top of mind for engineers and product teams. The difference between an inferior product and a superior one often comes down to finishing, and engineers treat parts after manufacturing to achieve certain aesthetic and mechanical properties. For example, sand or bead blasting creates a smooth surface texture that&#;s very noticeable in softer metals and buffing acrylic improves appearance.

Electroplating, also known as electrodeposition, is a common metal finishing process that uses electricity to coat a part with metal to improve certain properties. Here&#;s everything you need to know about electroplating, from how it&#;s done to its most useful applications.

How does electroplating work?

Electroplating using electrical currents to dissolve metal, transform it into a thin layer, and deposit it on to the surface of a part. The electroplating process is comprised of four components &#; an anode, a cathode or substrate, an electrolytic solution that includes salts and the metal to be plated, and a power source.

First, the anode and cathode are placed in a bath of the electrolytic solution and connected to each other. Then, the power source sends a direct current (DC) of electricity to the anode. The current oxidizes the metal and allows the metal alloys to dissolve into the solution as positive ions. From there, the positive metal ions move over to the negatively charged substrate and settle onto the part as a thin layer of metal over time.

A wide variety of metals and combinations of metal alloys are compatible with electroplating, and each material offers different properties. Engineers often electroplate with copper for added heat resistance, zinc for added corrosion resistance, and nickel for added wear resistance. Careful material selection and requirements evaluation are key to achieving success with electroplating, as certain materials are ill-suited for this finishing option. Product teams must do their due diligence to ensure they&#;re using the best material for their project.

Although plastic generally doesn&#;t conduct electricity, it&#;s possible to electroplate plastic parts if the material is given a few extra treatments. Once plastics like nylon or polycarbonate have been electroplated, they have all the benefits of plastic, but feature a shiny, metallic finish. Plated plastic is also lighter and cheaper than metal, and doesn&#;t require any polishing in post-processing, making it an ideal choice for some product teams.

Outside of material considerations, there are a number of other factors that can impact the success of electroplating, including solution conditions, part placement, and electrical current. The temperature and chemical composition of the electrolyte bath can impact the effectiveness of electroplating, and so can the voltage of the electrical current. The placement of the anode relative to the cathode also matters &#; the distance that the dissolved metal must travel will impact how well the substrate is plated. Product teams should be sure to account for these factors.

Advantages and disadvantages of electroplating

The primary benefits of electroplating can be broken down into three broad categories &#; aesthetics, protection, and conductivity. This finishing process is a cost-effective way to improve the surface appearance of a substrate by coating it with an aesthetically pleasing material. Costume jewelry is an excellent example &#; manufacturers can use electroplating to coat a cheaper metal like pewter in a thin layer of gold or silver to offer the luxurious appearance of precious metals at a fraction of the cost.

Electroplating places a protective barrier around the substrate that protects the part from environmental wear, which adds hardness, corrosion-resistance, heat-resistance, and thickness.

What&#;s more, electroplating offers a cost-effective and efficient conductivity solution. Gold and silver are excellent electrical conductors, but they&#;re prohibitively expensive for many product teams. However, coating a part in just a thin layer of these materials via electroplating is enough to offer superior conductivity to electrical components and integrated circuits.

On the downside, electroplating is relatively time-consuming and does not provide the most uniform finish. Also, if the electroplating solution is not disposed of properly, it can become an environmental hazard, so pollution is a concern.

Common applications for electroplating

These limitations notwithstanding, electroplating is a versatile finishing process that&#;s applicable to a wide range of industries. Electroplating is very common in medical device manufacturing because many devices contain nickel, but nickel cannot come into contact with the body. To work around this and improve biocompatibility, engineers often plate with palladium or gold. This process also improves catalytic converter performance in the automotive industry and improves the conductivity of circuits, making it well-suited for a variety of applications in the semiconductor industry.

Getting started with electroplating

Engineers should consider electroplating if they want to protect their part from heat, corrosion, wear, and other environmental factors, or give their part an attractive, decorative finish. As always, it&#;s important for product teams to do their research and make sure they&#;re considering all of the factors at hand &#; cost, aesthetics, function, and other relevant project-specific requirements &#; when selecting a post-processing or finishing option.

After 40+ years of making jewellery (and avoiding electroplating) I have an order for a bunch of silver pins that require a gold border and script.
I am not a fan of electroplated pieces at all but this is a requirement.

The piece is a bit complicated in that the centre must remain silver and there is an enamel inlay with gold plated lettering and border. (dimensions are 1 inch x 3/4 inch of cast sterling)

Couple questions to you who may be willing to make a suggestion.

1 Would a pen plating setup create a decent thickness of gold for a pin like this?

2 For a full bath setup (I have been researching) do you have any recommendations ?

Thanks in advance for any guidance.

Cheers

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For more information, please visit electroplating machine.

TerryV

Thank you &#; Appreciate your suggestion &#; I am actually looking into a local company to get a quote. I am in Canada and the border/customs is nightmarish now. Even ordering from Stuller has become dreadful. Packages hit customs in Montreal&#;sit often for a month, then without even looking at the invoice that I have paid taxes, access maximum and when I finally get the package have to pay through the nose &#; Thank you very much for your reply! I realize that plating is not something most of us go to. Personally I love the look of natural metal , not covering it up and hiding it. (But jobs are very scarce these days so one does what one must) cheers&#; TerryV

If you decide to try it yourself, it&#;s my understanding that gold plating over silver,
without first plating it with a nickel plating, will allow the silver to oxidize fairly rapidly. The gold plating is too porous to prevent the oxidation. Plating first with the nickel seals the silver and puts a hard layer on, so it won&#;t oxidize when you use the gold plating. I found this out many years ago when I was putting together a sample line of CZ and silver rings that I needed to be gold color. I end up having to nickel plate them all before using gold plating.

I just looked at them, and they look ok, all things considered, for being close to 30 years old. As Jo Haemer mentioned in another thread, &#;Electro plating is only molecules thick and will wear away.&#;

On the areas that will remain silver, you&#;d have to mask them, to protect them form being plated. For this, I used a bright red finger nail polish.

I&#;ve only used a pen plating set on rare occasions, and it might work for the lettering. Not sure what effect the oxidation would be without the nickel under the gold.

My experience was a long time ago and there might be newer, better ways to accomplish what you are trying to achieve. But, what ever approach you try, it probably will be labor intensive, so take that into account when you estimate your costs, just saying.

Tjones
Goldsmith

Some of you work over the years

Yes indeed &#; There is likely a reason I have avoided using this process in any of my work since beginning in the late &#;s.
I have never been a fan of the commercial trickery stuff &#; or bringing cyanide into my studio.
I can certainly see now that my quest is to job this stage out to someone who knows the techniques and is willing to take it on.
Now I am waiting for some vintage dies (I haven&#;t seen them yet) that I believe are steel to make pins in a hydraulic press. Another road I have not travelled &#; Years ago I would have been excited to take out a loan to buy new equipment but in today&#;s shaky marketplace //// Maybe not!
Thanks again to everyone

TerryV

No, pen plating isn&#;t thick enough. Silver requires a &#;strike coat&#; of either Nickle or Palladium before the gold. Palladium is preferred due to Nickle allergies. Also a sufficient coat of Palladium prevents copper migration to the surface where you get tarnishing. We do 2 minutes in the Palladium to achieve this.

Setting up plating is not terribly difficult. Check with your supplier to see if they have jewelers who can answer your questions and help you. For example both Rio Grande and Stuller have this available. I found that very helpful when I started with plating.

Equipment has to include a rectifier which converts the AC from the outlet to the DC that plating requires. Small scale can be done in glass beakers or glass dishes. You can get an all in one set-up with multiple tanks and rectifier included. The budget can vary broadly. You might find plating machines in the thousands of dollars or buy the things needed for significantly less. I set up 2 lines that run production and the equipment can be minimal. We opted for NOT using plating machines because it&#;s easier to swap out equipment on an open line. Here&#;s your sequence:

Electro Cleaner (degreaser)>Rinse>Acid Dip (neutralizer)>Rinse>Palladium>Rinse>Gold>Final Rinse and steam or dry

All water MUST be distilled or deionized. You need at least one Rinse tank between baths (two is even better). Electro Cleaner, Palladium and Gold all need heat. There are non-cyanide based Gold solutions available. You would need anodes, which are the pieces of metal connecting the current to the liquid. Electro Cleaner uses stainless steel (some people use a stainless steel container so that becomes the anode, Palladium uses platinized titanium, most Gold can use either.

It is possible to be very safe and environmentally friendly in plating. I&#;ve set up several small production plating lines at our company and this is a must for a business. Best if you have an area that is dedicated to plating, it&#;s easier to keep from contaminating other things and easier set-up.

And after all that, it may be that sending your plating out is more economical and easier for you. There does have to be testing per your situation. Plating is easy once things are set up. I can train someone in an hour and they can run the plating line as long as someone can answer their questions, etc&#; If you REALLY want to learn plating, that is a steeper learning curve. There are very few resources (books) geared toward the contemporary small shop. Specific information is more easily acquired from other jewelers or suppliers.

Good Luck,

Ruthanne

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