What’s Electroplating? Definition, How It Works & Applications

Finishing the machined or manufactured components using the appropriate method ensures their longer durability. It is also critical for the functionality of some high-performance applications. Electroplating is one of the popular finishing methods that can customize the mechanical properties and appearance with the use of suitable plating metals. 

You can use gold, silver, copper, zinc, platinum, and other metals and alloys based on your requirements. It means you have enough options to achieve the desired aesthetic, corrosion resistance, enhanced hardness, and conductivity. 

This article will elaborate on the process, types, benefits, applications, and other various aspects to guide you through the electroplating finishes and how they can bring change to your products.

What is Electroplating?

Electroplating is an old surface treatment process in metal fabrication and manufacturing, invented back in 1805 by Brugnatelli. Initially, it was popular to plate gold on other metals. However, it is continuously evolving and becoming more and more applicable across all industries for both aesthetic and protection purposes. 

It involves adding a layer of superior metal or alloys on the substrate metal through electrochemical deposition. The workpiece(cathode) and plating source metal (anode) are immersed in the electrolyte solution and connected through a power supply. As current flows through the circuit, the metal ions from the anode move towards a negatively charged workpiece and form a layer all over the surface.

The hard plating of chrome, nickel alloy, and zinc can significantly enhance wear resistance, corrosion resistance, and durability of manufactured components. On the other hand, decorative plating like gold and silver is popular in jewelry and ornament finishing.

When to Use Electroplating?

You may have thought that electroplated coating is only for aesthetic appeal and protection from external conditions, but there are other uses too. It can customize the surface properties by adding a layer of suitable metal through electrolysis. Here are the five conditions or scenarios when you can use the electroplating finish. 

Dimensional Precision (Build thickness)

If any parts or products are shorter in dimensions than expected values, the layers of plating material can correct that through a successive building. It allows for control of the plating thickness through process variables, such as voltage, time, and electrolyte concentration.

Aesthetic Requirements

You can use electroplating finishes to customize the surface appearance. Simply, the deposition of aesthetically pleasing metal and alloys on the substrate surface gives the permanent appearance of that metal or alloy. This way you can achieve the desired luster, brightness, and texture. For example, chrome plating on aluminum and steel parts makes their surface shiny and reflective.

Need for Corrosion Protection

If your manufactured parts are made from corrosion-prone materials, you can coat them with hard and resistive metal. The plated layer sacrifices itself in harsh operational and environmental conditions like chemical and moisture exposure to protect the underlying material.

Electrical Conductivity

You can easily achieve high conductivity on the connectors and terminal surfaces made with ordinary metals by plating high-conduction metals or alloys. Often, metals like gold, silver, and copper are electroplated onto components where high conductivity is required. 

Heat Resistance

For high-temperature applications, plating the components with metals nickel and chrome helps maintain the integrity of the underlying material at elevated temperatures. For example, plating the chrome-nickel coats on the automotive exhaust parts.

How Does Electroplating Work?

Electroplating works by dissolving and depositing a metal onto another surface through an electric current. There are four primary components of this process.

Anode: The electroplating metal or alloy that is going to be a plate on the substrate surface and connected with a positive (+) terminal. 

Cathode: The workpiece, connected with a negative (-) terminal. 

Plating Solution: The electrolyte that will carry the metal anions toward the cathode. It contains the metal ions that are to be deposited. E.g. CuSO₄ for copper plating.

Power Source: A DC supply to drive the metal ions from the anode to the cathode.

Electroplating Working Principle

The working principle of the electroplating process is based on the electrolysis mechanism. It says that passing current on an aqueous solution causes a non-spontaneous chemical reaction, where ions in the solution move toward electrodes. As a result, oxidation occurs at the anode.

Here, how does electroplating work;

1. Ionization of Electrolyte 

An electrolytic solution decomposes into metal anions cations when passing the electricity. For example, copper sulfate (CuSO₄) dissociates into Cu²⁺ (copper ions) and SO₄²⁻ (sulfate ions).

CuSO₄ (aq.) →Cu²⁺+SO₄²⁻ 

2. Oxidation at Anode or Plating material 

The anode continuously oxidizes (M→Mn⁺+ne²⁻) itself as its ions continuously move and build layers on the workpiece surface, continuously supplying the plating ions. For example, let’s consider the above example again copper as an anode;

Cu→Cu²⁺+2e²⁻ 

3. Deposition of Anions on the Workpiece Surface 

As the power continuously flows, the metal ions from the anode will travel to the cathode and will build the layer there uniformly. The thickness mainly depends on the concentration of irons and the time of electrolysis.

Again, the same example 

Cu2+(aq.) +2e−→Cu (s): Deposition on the cathode, i.e. aluminum, stainless steel, etc. 

Meanwhile, the free salt ions (SO₄²⁻ in this case) go to the anode and form the metal sulfate, facilitating the continuous oxidation. 

Precautions in The Electroplating Process

• Handle the electroplating batch with great care, as it contains sulfuric acid and is highly corrosive. If the solution or electrolyte comes into contact with your eyes, rinse them thoroughly with water and seek medical attention immediately.
• Always wear safety gear such as goggles and gloves to avoid direct contact between electrolytes and skin. Additional important equipment includes an apron and a fume hood. Ensure the fume hood is in use to prevent electrolyte fumes from reaching your face.
• Avoid any contact between electrolytes and household chemicals, as such contact can trigger reactions that may render the electrolyte useless or release hazardous gases into the atmosphere.
• Store electrolytes at an ideal temperature between 40 to 95 degrees Fahrenheit. Additionally, always keep them in the original container with the lid tightly sealed.
• Follow all electrical safety precautions, including using rubber mats, grounding, fusing, and insulated gloves.
• Please refrain from wearing rings or other jewelry during the process, as they are often metallic and could cause electrocution.
• Keep plating solutions out of the reach of animals and young children.
• Use a plastic funnel when transferring the electrolyte from the electroplating kit.

Types of Electroplating Techniques

There are different types of electroplating methods to employ when coating a substrate. These include:

• Barrel Plating
• Rack Plating
• Brush Plating
• Pulse Plating

Let us discuss these methods in more detail.

Barrel Plating

The barrel electroplating type uses a “barrel”, usually made with strong and chemically resistive material like polypropylene as an electrolysis container. The substrate parts are immersed inside the barrel with an electrolytic solution and anode. Then, the rotation of the barrel ensures the uniform coating of each part. However, it can cause minor imperfections and scratches.

You can use barrel plating to coat large volumes of small-sized parts at low cost. It is especially suitable for hard material parts like tool steel bolts, screws, liners, etc. 

Rack Plating 

In the rack plating, several parts are attached to a large rack structure inside the electrolytic bath. It can accommodate multiple parts at a single time holding with hooks, bands, or screws. Consequently, the work parts suffer minimal tumbling effect and can coat intricate features precisely.

The rack plating is suitable for both large-size parts and mass electroplating. However, the upfront installation cost and high labor cost are the drawbacks. You can plate copper, gold, nickel, etc. with this method.

Brush Plating

Although it is not exactly like painting the surface with brushes, a soft cloth (or cotton) wrapped electrode performs the electroplating.  First, the cotton is soaked in a plating solution containing the metal ions then operators manually apply the coating onto the specific areas.

Unlike the conventional setup, it is portable and offers high customization. You can achieve localized coating both for selective coating and repair purposes.  However, it is not suitable for parts with large and complex surfaces.

Pulse Plating

This type of electroplating finish uses electrical pulses to coat the substrate, the current switches quickly between two different levels and becomes zero in between, which generates the pulse. Meanwhile, controlling the pulse width and amplitude deposits the finer grains and achieves high uniformity.

The pulse plating is suitable for parts requiring a finish with minimal porosity, micro cracking, and roughness. However, the setup and operation are relatively more complex than other types of electroplating, 

Metal Materials Suitable for Electroplating

You can electroplate with either one metal or a combination of metals. There are many metals that engineers use for this process. However, below are the most common metals used.

Zinc Plating

Zinc is a low-cost plating metal that protects from moisture and gives a silver-like shiny appearance. It develops a sacrificial layer on the materials that are prone to rust formation, such as steel, iron, copper, aluminum, etc. As the electroplated product reacts with moisture over time, the zinc layer degrades itself first to shield the underlying material. You can use zinc plating for screws, springs, switch plates, brake pipes, and other small-size hardware.

Gold Plating 

First, gold plating gives a luxurious appearance to various decorative items, light fixtures, and jewelry components. Although foil coating is also popular for these uses, electroplated is much more strongly bonded and durable. 

Consequently, gold is a superior electrical conductor, and the coating lasts longer than other electroplating materials. It makes good plating perfect for high-performance electrical components like connectors, circuit cables, contact points in PCB boards, microelectronics, etc. 

Palladium Plating

It is the best alternative to gold and costs relatively low. Additionally, the palladium offers wear resistance and corrosion resistance while providing a shiny and bright silvery-white appearance. Palladium plating is used for copper, brass, and other metals to prevent their degradation.

Furthermore, it is often applied on a metal surface before the gold to achieve the balance of electrical conductivity and surface hardness. Other application examples include electronic connectors, medical and dental components, etc.

Silver Plating

Silver is another plating metal with high conductivity and load-bearing resistance. It also costs less than gold and provides more oxidation resistance. The silver-plated surface further reduces the coefficient of friction. Consequently, silver-plated parts are also flexible with the soldering. However, they are not as resistant to corrosion as gold or palladium.

The silver plating is best for both the finish and conductivity of the electronic connectors. It is also used in solar panels, semiconductors, connectors, bearings, etc.

Nickel Plating

The nickel plating on substrates like steel, copper, and aluminum results smooth and durable finish. Sometimes, nickel also serves as the base plate for subsequent coats like silver or gold. Moreover, it provides corrosion resistance, longevity, and magnetism, whereas it is also heat-treatable for further surface hardness. 

You can electroplate Nickel to achieve both a bright and dull surface. Meanwhile, it has numerous color options if you want to customize the appearance. 

Copper Plating 

Copper is the most common material in electroplating, which is applied to diverse types of materials for high conductivity, lubricity, biocompatibility, and relatively low cost. The smooth and consistent copper alloy plating not only provides a shiny and bright surface but also provides excellent electrical and thermal conductivity. 

Chrome Plating 

Chrome is a highly corrosion-resistant metal with excellent mechanical strength, wear and abrasion resistance, hardness, and durability. Plating the chromium gives the substrate additional strength and hardness along with the shiny luster appeal. It can be applied to aluminum, steel, and other relatively soft metals and alloys. 

Its applications range from decorative furniture to industrial components, such as automotive & aerospace parts. 

Advantages of Electroplating

Disadvantages of Electroplating

Industrial Applications of Electroplating

The electroplating method has applications in a wide range of industries. Let’s examine a few of them.

Aerospace

The protective sacrificial layer helps to improve the reliability and life of aircraft components. Manufacturers coat various titanium parts with nickel to withstand thermal changes and environmental stresses.  Additionally, precise dimensions and fits are also critical in aircraft manufacturing. The plating finish on their components resists wear and maintains the correct dimensions required for performance and safety. 

Application Examples: Engine parts and turbine blades with nickel or platinum coating, hydraulic systems, fasteners, structural items, valve bodies, sensor components, etc.

Automotive 

The reliability of automotive components is critical for vehicle performance and durability. Therefore, automotive parts require hard and environmentally unaffected coating, the chrome, zinc-nickel, or palladium-plated surfaces can address these requirements. Additionally, the automotive manufacturer also uses electroplating treatment to customize the aesthetic appeal.

Application Examples: Bumper, piston, cylinder liners, shock absorbers, radiator grill, fuel injectors, battery terminal and contacts, interior trims, etc.

Electronics

First, the coating of superior electrical conductive metals on electrical connectors, contacts, cables, and joining changes the complete electrical properties of the workpiece surface. It improves the performance and efficiency of electrical circuits.  Secondly, plating is also useful for the aesthetic design of enclosures and their protection from UV, corrosion, abrasion, and minor impacts. Moreover, gold, copper, nickel, and palladium electroplating are the most popular in the electronics industry. 

Application Examples: Connector pins, PCBs, semiconductors, capacitors, switch plates, battery contacts, sensors, and microelectronics parts.

Jewelry

Gold and gold alloys are most popular in jewelry plating to enhance the aesthetic appeal of ornamental items. It also provides a longer lifetime to them. Additionally, the combination of two or more types of metals gives unique appearances. You can apply other precious metals too, such as silver and rhodium.

Application Examples: Bracelets, rings, necklaces, watches, earrings, and custom items.

Electroplating Costs: What Influences the Price?

The prices can vary on different factors like which metal are you going to deposit, what is the thickness of the desired coating, whether the parts are too complex or not, and what is your production volume. All of these factors combined decide the electroplating cost.

Here is a brief elaboration of key influencing factors;

1. Material Selection

The overall coating cost is significantly affected by your material choices. It means which metal, alloy, or specific combination you want to electroplate. Especially, gold, platinum, and palladium are expensive than other metals. On the other hand, copper, nickel, and zinc are way cheaper.

Next, the exact material cost refers to the price of the total plating layer weight; a thicker layer means more material cost. 

Material Cost= Weight X Cost/kg = (Surface area x thickness x density) x $/kg 

2. Complexity and Precision 

Electroplating of intricate details or hidden areas requires specialized equipment and careful handling of the process. Often, recesses, blind holes, or internal cavities require masking techniques or multiple plating cycles for uniformity. It means slower production and more strict quality control procedures, which further increases the cost.

3. Production Volume 

High volumes typically reduce the cost per unit due to economies of scale, as setup, tooling, and overhead costs are spread across more units. Conversely, low-volume production leads to relatively higher costs per unit. 

At RapidDirect, you can get an accurate quote on how much your specific electroplating project costs.

Selecting the Right Electroplating Service Provider: What to Look For

The capability and experience of your electroplating service provider decide the end quality of the surface finish. Therefore, it is essential to consider several factors to select a reliable company that can fulfill all your requirements and coating specifications.

Here are the tips you can consider;

Equipment and Tools 

Does the manufacturer have the necessary equipment and facilities to achieve your electroplating specifications, including the size of parts, precision, thickness capability, etc.? Choose the manufacturer that has all the necessary electroplaters and tools to execute your finishing requirements. The processing capabilities also decide the lead time, cost, and accuracy. 

Quality Control

Like every type of surface finish, quality control is a critical aspect of electrolytic plating to ensure that each parts are electroplated with exact specifications (Ra value, color, texture, etc.). So, ask your service providers which standards they follow and what equipment they have to conduct the tests. Some companies also provide third-party quality control facilities for sensitive items like medical and aerospace components. 

Expertise and Experience

Look for a company that has a track record of working on metal electroplating similar to your project. For example, choose a company with experience in handling surface finishing projects for automotive companies if you are looking for electroplated bumpers. The experience ensures that they have related professional expertise to meet your expectations. 

Customer Support 

Responsiveness, timely communications, technical proficiency, and other customer-related aspects matter in the seamless completion of the project on time. Meanwhile, any misunderstanding of design can lead to complete failure. Therefore, ensure the customer support team has the technical expertise to offer informed advice, resolve issues, clear updates, and follow-ups.

Electroplating vs Electroless Plating

We discussed creating a protective layer of one metal on to surface of another metal by using electricity. However, it is also possible to add layers of various metals and alloys to manufactured components without using electricity, called electroless plating. Instead, chemical reactions and heat bind the coating material onto immersed substrates. Electroless nickel and chrome plating are most common across the industries.

The electroless method is also compatible with non-conductive materials like thermosets and composites. Since there is no electrochemical process, setup is simpler and cost-effective. Many industrial components need thicker and harder layers for high-stress operations. It can achieve such hard metal coatings with superior wear resistance, and thickness up to 200 µm. 

However, the deposition rate is slower in electroless coating and the thickness control is less precise than electrochemical deposition. Unlike electrolytic plating, it is challenging to automate the process.

Electroplating vs Electroforming

First, the similarity between these two processes is that both involve electrodeposition. Electroplating builds a protective coating of metal on already manufactured items, whereas electroforming creates completely new parts by depositing the materials inside a pre-shaped mold, often called a mandrel. Then, the part is removed from the mold. It makes small and complex shapes with microfeatures.

Why Choose RapidDirect for Your Electroplating Needs

Every electrochemical metal plating process requires electrolysis as its base. However, what differentiates one electroplating process from another is the solution employed during the process as well as the expertise of the professional. If need metal parts with electroplating finishing, RapidDirect is your best bet.

To ensure your product stands out among competitors, RapidDirect applies a top-quality surface finish with exquisite materials that meet your requirements. Besides, we use high texturization standards to ensure a quality finish for metallic parts. Also, since we consider time an important factor in production, we shorten the production process using our self-owned factory and its established networks.

At RapidDirect, our manufacturing ability is versatile and aids in the production of high-precision and top-notch metal parts, ranging from CNC machining machines to sheet metal fabrication services. Our sheet metal fabrication aids in the production of high-precision and top-notch metal parts.

Besides, our strict quality assurance ensures you get high-quality metal parts with outstanding finishing and aesthetics. What’s more, you can get a quote for your electroplating, and other manufacturing needs easily by visiting our online platform.

Conclusion

The electroplating process is one technology that has been around for a long time. It aids in the production of parts that have improved properties and are durable and aesthetically pleasing. For electroplating to be successful, it requires an anode, cathode, electrolyte, and power source.

Are you looking to electroplate an object? Doing so without proper guidance or training is a risky affair. So, you should visit RapidDirect to find out about your electroplating needs.

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