Turn Plastic into Real Metal: The Secrets to Electroplating 3D Prints

Besides the electrolyte solution that should be handled and disposed of carefully, preparing 3D printed parts and electroplating them should always be executed with the appropriate protective equipment—proper clothes, gloves, goggles, and a respiratory mask are necessary. Spraying and electroplating should also be done in a well-ventilated area to avoid breathing in harmful substances. As always, follow the handling and storage instructions for the used materials. But for now, let’s look at the necessary steps before plating.

3D Printing the Part

When plastic 3D printing for electroplating, the most used technologies are SLA and FDM, but SLS and material jetting are also possible, yet more expensive.SLA printing has a competitive edge due to the achievable detail resolution. In both cases, the better the printer resolution and the lower the layer thickness, the less post-processing the part requires. In terms of material, anything that the conductive paint sticks to can be 3D printed. Some specialty service providers can even print and plate industrial materials like Nylon and PEEK.

Sanding the Part

One of the most elementary requirements for electroplating is a smooth surface to yield good results from the fragile film that’s only a few hundred microns thick. The smoother the surface, the shinier the final metal coating. Especially for FDM printed parts, this means several rounds of vigorous sanding and filler spraying. Polyurethane varnish also helps fill any gap in the print.

Cleaning the Part

Just as important as a smooth surface is a clean surface, not just before starting the electroplating process but between every step. Dust and grease are the mortal enemies of electroplating, as they prevent the filler, conductive paint, and subsequent metal coatings from binding uniformly to the part. Clean and degrease your part thoroughly before placing it into the bath and clean it with distilled water between the electroplating steps.

Making the Part Conductive

To make the part conductive, apply a layer of conductive paint. Copper or Nickel paint is most commonly used, but much cheaper graphite paint will also do the trick if sanded once more before dipping it into the electrolyte. Not every filler is compatible with graphite paint, however. Youtube creator HEN3DRIK has a formidable tutorial on graphite electroplating along with a wealth of other electroplating resources. There have also been attempts at printing with conductive filament to avoid having to apply a conductive paint layer, but results have been mixed, so going the way of the spray is recommended, especially for novices.

Immersing the part

Set up the electrical circuit by attaching the electrodes to your power supply. The anode needs to be attached to the metal forming the plating. The cathode will be connected to your part. Cut a metal wire to length and shape it so your 3D printed, primed, and cleaned part can sit in it. Some 3D prints want to float, so hold them down with the wire if necessary. Remember to reposition the piece while plating periodically, or it will weld to the wire. Fill a glass or plastic container with the appropriate electrolyte and ensure the part to be plated is completely submerged.

Electroplating the Part

Everything is set up, and you can turn on the power supply. The needed current depends on your model’s thickness, surface area, and tank volume. There are online calculators that help you figure out the required voltage. For best results, it makes sense to increase power as the deposited layer gets thicker gradually. Too much current will lead to uneven coating with rough and grainy deposits and faster electrolyte degradation. A weak current will result in insufficient metal deposition leading to thin or patchy plating.

Further Processing the Part

The electroplated part can then be further plated with other metals like nickel, gold, or palladium. This can be done either through further electrolysis or other methods like brush plating. The part can also be chemically cleaned to increase the film’s reflectivity further.

Electroplating is a complex process requiring a high level of diligence and experience to satisfy results. This section summarizes some of the most common defects, how they happen, and what can be done to avoid them.

Part Geometry Defects and Issues

The geometry of a part plays a crucial role in guaranteeing electroplating success. Conventionally manufactured substrates made with plastic injection molding or metal casting often exhibit surface irregularities that make even metal deposition challenging. Cold shuts, for example, occur when materials harden at different stages of the injection process, leaving behind visible flow marks or lines. Pitting, another common issue, refers to small holes on the substrate’s surface.

Their equivalents in the 3D printing realm are layer lines and material under- or overextrusion issues. These process-specific phenomena cause deviation from the final part dimensions. They must be handled via sanding and priming before electroplating because such significant irregularities can not be fixed once the metal film has been deposited.

Even intentional part geometries like sharp edges or intricate designs like lattices can cause issues during plating because of current distribution issues. Current density is higher at sharp edges, meaning excessive coating will occur in these areas, leading to a brittle layer that easily breaks. The opposite of that is shadowing, which can be understood similarly to the sun casting a shadow. Parts of the substrate that are covered from the anodes will receive less deposition. This can be solved by rearranging the anodes or continuously turning the substrate within the electrolyte for distributed part exposure.

Poor Adhesion

Poor adhesion between substrate and metal finish may have several reasons. Firstly, if the plastic part and conductive coating don’t bond together well, they will separate, and with it, the metal plating, even if it has been deposited as it should. Finding the right combination of plastic and paint coating is crucial. On top of good bonding qualities, the working surface also needs to be free from grease, dust, or oxidation, all of which compromise adhesion. Because plastic and metal expand differently under heat, even a perfect coating can crack and detach over time if the part is exposed to such an environment. In this case, electroplating with a different material combination or going the way of metal 3D printing may be the best solution.

Uneven Plating

Suppose the finished plating is not just dull but also rough. In that case, the electrolyte may be degraded and contaminated by particulates that will deposit on the substrate, leaving behind an uneven coating. Filtering or replacing the electrolyte will help.

Excessive current also leads to uneven coating; thus, decreasing the current will often alleviate the issue. Bubbles forming on the substrate are usually a telltale sign. However, if the current is too low, the coating may be too thin or even patchy and incomplete. Finding the right balance is one of the most critical aspects of electroplating success.

Dull and Hazy Plating

It can be frustrating when the plating is successful but does not exhibit the desired shine and reflectivity. There are many reasons why this may have happened. A chemical imbalance like too much sulfate, chromic acid, or contaminants dissolved in the electrolyte may be the cause, so changing the electrolyte could improve results. Incorrect temperatures may be another reason. Temperatures between 130 and 140°F are ideal for both the bath and the substrate.

Incorrect current density or a broken power supply leading to interrupted currents may also be the root cause. The part itself may also be placed too high in the container. Make sure that it’s at least four inches below the surface. Lastly, inadequate rinsing between electroplating steps may lead to chemical or dirt residue and subsequent dullness. If none of these fixes deliver the desired results, using a brightener can also help improve the final result as it stops large crystals from forming on the part, making it shinier.

Like any technology, electroplating has pros and cons, some of which have already been mentioned in the article and will be summarized here. In addition to common electroplating-specific considerations, a few more must be considered when combining it with 3D printing. The following list summarizes these benefits and drawbacks.

Pros of Electroplating

• Improved surface appearance
• Protects the substrate material from mechanical wear, corrosion, or tarnishing
• Improves part properties like tensile strength, stiffness, and weight
• Creates new properties like magnetism or electrical conductivity
• Enables the coating of different metals, including copper, tin, nickel, gold, palladium, chrome, and more
• Low-cost alternative to metal 3D printing that enhances plastic parts with metal characteristics

Cons of Electroplating

• While cheaper than 3D printing with metal, the required materials are expensive and add to the cost of the final part
• Tedious and manual process with process-specific defects like cold shuts, pitting, sharp edges, cleavage points, and loss of adhesion that make the process challenging to master, especially in a hobbyist setup
• The differing thermal expansion properties of plastic and metal can lead to cracks and separation of the coating from the substrate over time
• Mechanical properties do not come close to metal parts
• Lengthy process that takes several hours to days, depending on the required finish
• Toxic materials that create hazardous waste and can damage the environment if incorrectly handled and disposed of

Since electroplating is a well-established finishing technique, most manufacturing sectors, including additive manufacturing, use it in selected applications to improve part characteristics like conductivity, durability, visual enhancement, or strength. Such industries include the automotive, aerospace, electronics, medical, and fashion industry. In the latter, it has been used by shoe designers and jewelry makers to give their products a more luxurious look and feel. Electroplating a plastic or metal ring with a microscopic layer of gold will be much more affordable but provide the same elegant look. It also allows makers without access to goldsmithing equipment to upgrade their 3D printed plastic parts at relatively low costs.

This also applies to hobbyists like a model and miniature makers who want to turn their SLA 3D printed designs into shiny, heavier figurines or life-like props resembling polished metal. Many artists also combine the versatility of 3D printing with the stunning looks of electroplating to create works of art like Michael Cardacino’s “Emptiness of Shark,” a hollow  6-foot shark sculpture that was SLS-printed on an EOS P730 in several parts, assembled, and electroplated in copper and nickel by Repliform.

Moving to industrial 3D printing and electroplating, Elliptika, a radio frequency and microwave product and solutions specialist, uses additive manufacturing to design complex radiofrequency antennas that are 80% lighter at the same performance as their full-metal counterparts. The company also managed to 3D print high-performance antenna parts at 90% lower cost than conventional methods, making the production of small-volume parts quicker and much more cost-effective. In the automotive industry, electroplating is also often used to improve the visual appeal of concept cars or to manufacture spare part reproductions for classic car models.

Several on-demand 3D printing services offer electroplating, also called just plating, as a type of finishing to your 3D print. Conveniently, you can just upload your digital file and these companies will take care of printing, prepping, and plating your part.