Electroplating is a popular metal finishing and improving process used in a wide range of industries for various applications. Despite the popularity of electroplating, however, very few outside of the industry are familiar with the process, what it is and how it works. If you're considering using electroplating in your next manufacturing process, you need to know how the process works and what material and process options are available to you.
What Is Electroplating?
Electroplating is also known as electrodeposition. As the name suggests, the process involves depositing material using an electric current. This process results in a thin layer of metal being deposited onto the surface of a workpiece called the substrate. Electroplating is primarily used to change the physical properties of an object. This process can be used to give objects increased wear resistance, corrosion protection or aesthetic appeal, as well as increased thickness.
While electroplating may seem like advanced technology, it is actually a centuries-old process. The very first electroplating experiments occurred in the early 18th century, and the process was officially formalized by Brugnatelli in the first half of the 19th century. After Brugnatelli's experiments, the electroplating process was adopted and developed across Europe. As manufacturing practices advanced over the next two centuries through the Industrial Revolution and two world wars, the electroplating process also evolved to keep up with demand, resulting in the process Sharretts Plating Company uses today.
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The electroplating process uses an electric current to dissolve metal and deposit it onto a surface. The process works using four primary components:
- Anode: The anode, or positively charged electrode, in the circuit is the metal that will form the plating.
- Cathode: The cathode in the electroplating circuit is the part that needs to be plated. It is also called the substrate. This part acts as the negatively charged electrode in the circuit.
- Solution: The electrodepositing reaction takes place in an electrolytic solution. This solution contains one or more metal salts, usually including copper sulfate, to facilitate the flow of electricity.
- Power source: Current is added to the circuit using a power source. This power source applies a current to the anode, introducing electricity to the system.
Once the anode and cathode are placed in solution and connected, the power supply supplies a direct current (DC) to the anode. This current causes the metal to oxidize, allowing metal atoms to dissolve in the electrolyte solution as positive ions. The current then causes the metal ions to move to the negatively charged substrate and deposit onto the piece in a thin layer of metal.
As an example, consider the process of plating gold onto metal jewelry. The gold plating metal is the anode in the circuit, while the metal jewelry is the cathode. Both are placed in solution and DC power is supplied to the gold, which dissolves in solution. The dissolved gold atoms then adhere to the surface of the base metal jewelry, creating a gold coating.
While this process is constant, three factors can impact the quality of the plating. These factors are the following:
- Bath conditions: Both the temperature and the chemical composition of the bath impact how effective the electroplating process is.
- Part placement: The distance the dissolved metal needs to travel will affect how effectively the substrate is plated, so the placement of the anode relative to the cathode is important.
- Electrical current: Both the voltage level and the application time of the electrical current plays a role in the efficacy of the electroplating process.
Which Metals Are Used in the Electroplating Process?
Plating can occur with individual metals or in various combinations (alloys) that can provide additional value to the electroplating process. Some of the most commonly used metals for electroplating include:
- Copper: Copper is often used for its conductivity and heat resistance. It is also commonly used to improve adhesion between layers of material.
- Zinc: Zinc is highly corrosion-resistant. Often, zinc is alloyed with other metals to enhance this property. For example, when alloyed with nickel, zinc is particularly resistant to atmospheric corrosion.
- Tin: This matte, bright metal is highly solderable and corrosion resistant as well as environmentally friendly. It is also inexpensive compared to other metals.
- Nickel: Nickel offers excellent wear resistance, which can be improved through heat treatment. Its alloys are also very valuable, offering elemental resistance, hardness and conductivity. Electroless nickel plating is also valued for its corrosion resistance, magnetism, low friction and hardness.
- Gold: This precious metal offers high corrosion, tarnish and wear resistance and is coveted for its conductivity and aesthetic appeal.
- Silver: Silver is not as corrosion resistant as gold, but it is highly ductile and malleable, has excellent resistance to contact wear and offers excellent aesthetics. It is also an alternative to gold in applications where thermal and electrical conductivity is needed.
- Palladium: This bright metal is often used instead of gold or platinum for its hardness, corrosion resistance and beautiful finish. When alloyed with nickel, this metal achieves excellent hardness and plating quality.
Price, substrate composition and desired result are key factors when determining the most appropriate electroplating material for your application.
There are several different plating techniques available, each of which can be used in various applications. Some of these types of electroplating are described in more detail below:
- Barrel plating: Barrel plating is a method used to plate large groups of small parts. In this process, parts are placed inside a barrel filled with an electrolyte solution. The electroplating process proceeds while the barrel is rotated, agitating the parts so that they receive consistently even finishes. Barrel plating is best used on small, durable parts, but offers a cheap, efficient and flexible solution.
- Rack electroplating: Rack or wiring plating is a good option if you need to plate large groups of parts. In this method, parts are placed on a wire rack, allowing each part to come into physical contact with the electrical power source. Though more expensive, this option is optimal for more delicate parts that cannot undergo barrel plating. It is important to note that rack plating is more difficult for parts that are sensitive to electricity or have an irregular shape.
- Electroless plating: Electroless plating, also known as autocatalytic plating, uses a similar process as electrodeposition but does not directly apply electricity to the part. Instead, the plating metal is dissolved and deposited using a chemical reaction in place of an electrical one. While this option is useful for parts that are incompatible with electrical currents, it is more costly and less productive than other options.
While these methods accomplish electrodeposition in different ways, they all use the same basic principles.
Uses of Electroplating
While electroplating is often used to improve the aesthetic appearance of a base material, this technique is used for several other purposes across multiple industries. These uses include the following:
- Build thickness: Electroplating is often used to build up the thickness of a substrate through the progressive use of thin layers.
- Protect substrate: Electroplated layers serve as sacrificial metal coatings. This means that when a part is placed in a harmful environment, the plated layer breaks down before the base material, protecting the substrate from damage.
- Lend surface properties: Electroplating allows substrates to benefit from the properties of the metals they are plated with. For example, some metals protect against corrosion, improve electrical conductivity, reduce friction or prepare a surface for better paint adhesion. Different metals lend different properties.
- Improve appearance: Of course, electroplating is also commonly used to improve the aesthetic appearance of a substrate. This can mean plating the substrate with an aesthetically pleasing metal or simply applying a layer to improve surface uniformity and quality.
Benefits of Electroplating
Electroplating offers a range of benefits for components. Some of the specific benefits of electroplating include the following:
- Protective barrier: Electroplating creates a barrier on the substrate, protecting it against environmental conditions. In some cases, this barrier can protect against corrosion caused by the atmosphere. This property specifically benefits components because the parts last longer in more harsh conditions, meaning that they need less frequent replacement.
- Enhanced appearance: Exterior pieces are often plated with thin layers of precious metals to make them more lustrous and attractive to look at. This plating lends aesthetic appeal without exorbitant costs, meaning that attractive parts can be sold at lower prices. Additionally, electroplating is often used to prevent tarnishing on silverware, improving longevity and aesthetic appearance over time.
- Electrical conductivity: Silver and copper plating help improve electrical conductivity in parts, offering a cost-effective, efficient solution for improving conductivity in electronics and electrical components.
- Heat resistance: Several metals, including gold and zinc-nickel, are resistant to high temperatures, improving the ability of the substrate to resist heat damage. This, in turn, can improve the lifespan of plated parts.
- Improved hardness: Electroplating is often used to improve the strength and durability of substrate materials, making them less susceptible to damage from stress or rough use. This quality can help increase the lifespan of plated parts, reducing the need for replacement.
Some benefits offered are metal-specific. For example, nickel plating is useful for reducing friction, which helps to reduce wear and tear and improve part longevity. Zinc-nickel alloys, on the other hand, are used to prevent the formation of sharp protrusions during manufacturing, which can result in part damage. Copper is also specifically used as an undercoating in many applications, as it facilitates adhesion with additional metal coatings to improve the surface quality of the final part.
Industries That Use Electroplating
Whether your company is looking for corrosion protection, improved durability or increased electrical conductivity, electroplating offers solutions. That's why electroplating is widely used across a variety of industries. Listed below are some of the industries SPC serves and how they apply electroplating:
- Automotive industry: Plating is commonly used in the automotive industry to prevent corrosion in harsh environmental conditions. Zinc-nickel plating solutions help prevent rust formation, while electroless nickel plating serves as a great alternative for chrome on catalytic converters and plastic parts.
- Electronics industry: Electronics companies often use gold plating for its conductivity, applying it to semiconductors and connectors. Gold is also coveted for its corrosion resistance in this industry. Copper plating is another commonly used metal in this industry, used as an alternative to gold when the focus is on conductivity. Palladium alloys are also commonly used as protective coatings on electronic equipment and components.
- Medical industry: The medical equipment industry often uses metal electroplating to improve the biocompatibility of components, especially implants. Gold, silver and titanium are commonly used in this industry for their biocompatibility, corrosion resistance, hardness and wear resistance, all of which are essential for implants and joint replacements.
- Aerospace industry: The aerospace industry frequently uses titanium for aircraft manufacturing due to its high strength-to-weight ratio. Nickel plating is also commonly used in this industry to protect against corrosion and wear, while copper is used to improve heat resistance.
- Oil and gas industry: Corrosion protection is a primary concern of the oil and gas industry due to the nature of petrochemicals. Electroless nickel plating is often used in this industry to help protect piping and other components from corrosion, which helps improve the longevity of parts.
Many other industries, including the firearms, military and defense industries, also use electroplating in various applications. All of these industries favor electroplating for its functional capabilities, as well as its low cost and flexibility of application.
There are many specific examples of electroplating applications across various industries. Some of these are detailed below:
- Copper plating of semiconductors: Various metal plating options are used in the electronics industry. Copper plating is commonly used to increase the ability of semiconductors and circuits to conduct electricity.
- Nickel plating of hard drives: Nickel is a magnetic metal, which is an essential property for hard drives. Hard drives require magnetism to improve disc reading, so hard drives are commonly electroplated with nickel during the manufacturing process.
- Palladium plating of catalytic converters: Palladium plating is commonly used in the automotive industry, specifically on catalytic converters. Palladium absorbs excess hydrogen during the manufacturing process, an element that negatively impacts the functionality of catalytic converters. Plating with palladium absorbs this excess hydrogen, improving catalytic converter performance.
- Electroless nickel plating of aerospace components: Black electroless nickel plating is capable of absorbing light and energy. This is an essential quality in the manufacturing of various types of defense vehicles. Many defense and aerospace industry manufacturers choose to use this plating option to ensure compliance with industry standards, including the Department of Defense guidelines.
With our extensive experience in a range of industries, SPC can assist with these electroplating applications and more, offering a range of cost-effective plating services.
Determining your best manufacturing options is essential for your company's efficiency. Electroplating serves as a functionally and financially beneficial option for a variety of applications, but you need to partner with the right plating company to see all the benefits. Sharretts Plating Company can help.
SPC has over nine decades of experience in the industry, developing a wide range of cost-effective plating and metal finishing processes to suit the needs of companies across numerous industries. We can help you determine the best plating method for your project, as well as the type of metal you'll want to use. With SPC, you can trust us to provide experienced, customer-focused service from start to finish.
Contact SPC to learn more about the electroplating process and how it could benefit your business and request a free quote now!
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"I would like to thank you for the help you have provided us in developing an electroless nickel plating technique on an unusual substrate. The sample platings you provided show that we should be able to reach our goals. I especially appreciate your willingness to take on an unusual job, with the uncertainties that that entails...We are looking forward to working with you in the future on our plating needs."
– Robert K.