Metal Plating Finishes: Process, Types And Applications
In the dynamic world of modern manufacturing, metal plating has proven to be an important and indispensable process. Plating companies play a crucial role in the metal plating industry by providing top-quality plating services and solutions across various sectors.
It allows you to combine the strength, aesthetics, conductivity, and durability of specific metals with other materials that offer their own benefits, creating an overall superior product. This process is used in virtually all industries thanks to its cosmetic and functional benefits.
This comprehensive guide explores the core principles of metal plating finishes. Here, you’ll learn about the metal plating process, its applications, and the different material options that are available to you. The tips you get here are bound to help you in your next project.
What Are Metal Plating Finishes?
Metal plating finishing involves coating a component using a thin metal layer. The component being coated, known as the substrate, is typically a conductive surface made of metal or even plastic.
Metal plating surface coatings offer an array of benefits. You can improve the strength, durability, flexibility, wear resistance, and corrosion resistance of a part by simply plating it with a suitable metal. In some cases, this surface finishing treatment plays a decorative role.
What Is The Metal Plating Process?
There are different metal plating techniques namely;
Electroplating
Electroless plating
Immersion plating
Custom manufacturing companies, with their expertise in the metal plating process, play a crucial role in delivering high-quality results tailored to specific industry needs.
In this section, we’ll outline the steps for electroplating which remains the most popular metal plating technique.
Step 1: Substrate Pretreatment
Before you can start the metal plating process, you need to prepare the substrate surface by eliminating all dirt, oil, and other surface impurities. A clean metal surface will bind to the plating material more effectively producing higher quality metal finishing. Sandblasting and degreasing are some of the processes employed during the pretreatment stage.
Step 2: The Cleaning Process
A metal surface may appear clean but still have microscopic contaminants that can hinder the plating process. Cleaning is therefore done using physical and chemical methods to strip away any stubborn impurities.
The ideal cleaning method will vary depending on the metal substrate. For example, steel, copper, and titanium require an alkaline cleaner while other metals such as magnesium use an acid cleaner. Similarly, if you’re plating aluminum, zinc, or bronze you would use an inhibited alkaline cleaner.
Step 3: Assemble the Plating Station
Once your metal substrate is sufficiently clean, you can start the coating process by setting up the plating station.
The basic hardware for the electroplating process consists of:
Anode: The metal that you want to deposit over the workpiece is the anode or positively charged electrode.
Cathode: The substrate that needs to be plated is the cathode. It acts as the negatively charged electrode for the circuit.
Plating solution: The anode and cathode are placed in an electrolyte chemical bath
Direct electric current supply: An electric current facilitates the movement of ions, plating the workpiece with an even coating.
Your setup may also require a barrel, conductive rods, hangers, cables, and a conductive surface to ensure proper metal deposition.
Step 4: The Electroplating Process
The coating process starts when the electric current is turned on. The electricity causes the positively charged metal ions from the anode to move to the negatively charged surface of the cathode (substrate). The deposition of metal ions creates a thin coating on the workpiece.
The thickness of the plating layer will vary depending on the current and how long the substrate remains in the electroplating solution. For example, to obtain a thick layer of coating, you would need to expose the substrate to the current for a longer duration.
Step 5: Post Treatment
Once you’ve attained a proper coating, you may need to follow up with post-treatment cleaning. There is a comprehensive range of chemicals designed to help you with this step. After the cleaning operation, rinse off the cleaning chemicals and dry off the plated parts.
In some cases, you may require additional post-plating treatments such as coating, passivation, and electrolytic polishing.
Step 6: Waste Disposal
Metal plating often creates toxic waste that can be harmful to living organisms and the environment. This chemical waste material needs to be treated and disposed of responsibly following waste management regulations.
Types Of Metal Plating Finishes
There are different types of metal plating finishes, each with its unique properties, benefits, and potential downsides. The ideal solution will vary depending on the specifics of your project. Plating companies play a crucial role in providing various metal plating finishes, ensuring that you get the best solution for your needs.
Common industrial plating services include;
Zinc Plating
Zinc is a popular, shiny-greyish base metal that is primarily used for galvanization. Galvanization refers to a surface finishing process in which a ferrous metal, such as steel or iron, is coated with a thin layer of zinc. The zinc acts as a sacrificial coating, protecting the underlying metal substrate from rusting or corrosion.
Zinc plating is primarily used to prevent rusting and corrosion of other metals. This process also improves the strength, ductility, and aesthetics of a part. What’s more, zinc plating is cheaper compared to alternatives such as silver plating. These benefits make zinc the metal of choice for plating in various industries such as the military, construction, and automotive sectors.
Cadmium Plating
Cadmium plating is a conductive, corrosion-resistant coating process commonly used in the aerospace, military, and marine industries. It acts as a sacrificial coating, meaning that it is preferentially corroded and degrades over time instead of the underlying substrate.
While cadmium plating is still in use today, some manufacturers are opting for alternative coatings due to safety concerns.
Chrome Plating
The chrome plating process utilizes trivalent chromium baths or a chromic acid known as hexavalent chromium to create a coating on metal components.
There are two types of chrome plating; decorative chrome plating and hard chrome plating. As the name suggests, decorative chrome plating is mainly for cosmetic purposes and provides a shiny, mirror-like finish.
Hard chrome plating utilizes a thicker layer of chromium and is used for engineering purposes. This process improves the strength, toughness, and durability of a material. Hard chrome plating is commonly used in applications where there is a concern for wear since it lowers friction.
Nickel Plating
Nickel plating places a thin coating of nickel on a metal surface. The are two main types of nickel plating; electrolytic and electroless nickel plating. The electrolytic process uses an electric current and electrolyte solution while electroless nickel plating relies on a chemical reaction.
Nickel plating serves various purposes, including protection against wear and corrosion, improving surface tensile strength, and enhancing the aesthetics of a part.
Copper Plating
Copper has a lot of desirable properties such as malleability, conductivity, corrosion resistance, and best of all, cost efficiency. However, as a stand-alone material, copper is not suitable for applications that require strength. It can, however, be used as a coating while the core provides strength. The primary copper electroplating solutions are acid, alkaline, and electroless copper plating baths.
Copper plating is often used for electrical wiring and electronics thanks to its excellent conductivity at a competitive price.
Gold Plating
Gold plating involves depositing a thin layer of gold onto the surface of a base metal. This precious metal not only enhances the aesthetic appeal of objects such as jewelry but also serves functional purposes.
Gold is a noble metal that offers an exceptionally high resistance to oxidation and corrosion. This aspect means that it’s commonly used to protect metals exposed to harsh conditions. Due to its excellent electrical conductivity, gold plating is also used in electrical components.
Silver Plating
Silver has long been used as a plating material thanks to its many desirable properties. While this noble metal is lightweight and easy to work with, it also offers exceptional hardness and durability. Silver is also known for its aesthetic appeal, high conductivity, and corrosion resistance. It’s often used in medical gadgets such as stethoscopes and insulin pumps thanks to its antibacterial properties.
The most common methods of silver plating are barrel plating and rack plating.
Tin Plating
Tin plating has been around for centuries, serving a variety of purposes over that duration. There are three basic types of tin plating; barrel plating, rack plating, and vibratory plating. Each of these plating techniques involves immersing the metal substrate into an electrolyte bath.
Tin is a soft, malleable metal with a silvery-white appearance. It serves both functional and decorative purposes in plating applications. Tin plating is often used as a measure against oxidation and corrosion.
Rhodium Plating
Rhodium plating involves coating a base metal with a thin layer of Rhodium, a rare noble metal that is silvery-white in appearance. One of the most striking features of Rhodium is its brilliant shine. It’s, therefore, no surprise that jewelers often use rhodium plating to enhance the durability, scratch resistance, shine, and light reflection of jewelry.
Applications Of Metal Plating Finishes
Metal plating is used in a vast array of applications and industries including; automotive, aerospace, electronics, and medical devices. A custom manufacturing company can provide tailored metal plating solutions for these and other specific applications.
Automotive Industry
In the automotive space, metal plating serves a wide range of functions including improving conductivity, metallization of plastic parts, and providing protection from corrosion, wear, and tarnish. Zinc and Nickel are common plating metals that improve corrosion resistance and enhance the look of automotive parts.
Aerospace Industry
Sacrificial coating is often used to improve the durability of different aircraft components. This industry also utilizes metal plating finishes that are capable of withstanding high temperatures. Common plating materials for aerospace applications are nickel, cadmium, titanium, and chromium.
Jewelry Industry
Metal-plated jewelry has become increasingly popular as it improves the aesthetics and durability of jewelry. Gold, silver, and rhodium are some of the metals commonly used to create plated pieces. Another perk of plated jewelry is its affordability. For example, a gold-plated piece is more affordable than solid gold.
Medical Industry
Different medical gadgets also use metal plating. This can range from surgical tools to tooth inlays and orthopedic implants. Plating medical devices and implants helps with sanitation, biocompatibility, strength, and corrosion resistance.
Electronics Industry
Metal plating is a crucial process in the manufacture of electronic parts and components. It is used for corrosion protection and enhancing electrical conductivity, solderability, and wear resistance. Common plating materials in this field include gold, silver, copper, platinum, tin, and palladium.
What is the difference between electroplating and metal plating?
Metal plating is the process of coating a surface or substrate with a thin metal layer. Electroplating is a type of plating process that utilizes an electric current and electrolyte solution. In other words, metal plating can be done through electroplating or alternative techniques such as immersion plating and electroless plating.
What is the difference between Powder Coating and Metal Plating?
Both metal plating and powder coating are common post-production surface treatments. Powder coating involves spraying fine, electrostatically charged powder particles on the substrate surface and curing the coating with heat or UV light. Conversely, metal plating uses metal ions to form a protective layer over the substrate. Metal-plated components are often more durable than their powder-coated counterparts.
FAQ
What is the cheapest metal coating?
Zinc coating. Zinc is an inexpensive, readily available element that comes with a host of desirable properties. It is commonly used for steel and iron galvanization, where it provides excellent protection against rusting and corrosion.
What are the disadvantages of metal plating?
Metal plating generates toxic waste that can be harmful to both workers and the environment. Also, plating using expensive metals such as gold, silver, and platinum can get costly.
How to do steel plating?
Steel has applications in practically every industry. Steel plating services can solve the biggest challenge associated with steel products: rusting. Just like other metal substrates, you can successfully plate steel through electroplating or electroless plating.
Author
Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.