Plating is a metal finishing process used to apply a layer of one material to the surface of another. In industrial applications, this usually involves depositing a metal such as silver, gold, nickel, tin, copper or zinc onto a component to improve its surface properties.
The component being plated is known as the substrate or base metal. By applying a carefully controlled layer to its surface, plating can improve corrosion resistance, electrical conductivity, wear resistance, solderability and appearance without requiring the entire component to be manufactured from the plating material.
Plating is used extensively throughout manufacturing and engineering, including the electrical, electronics, automotive, aerospace, defence, rail, telecommunications, medical and energy sectors.
At Karas Plating, we have more than 70 years of experience in plating and metal finishing, working with manufacturers and engineers across the UK.
How Does Plating Work?
There are several methods of metal plating, but many industrial processes involve immersing a prepared component in a solution containing the metal that is to be deposited.
With electroplating, an electrical current is passed through the solution. This causes metal ions within the solution to deposit onto the surface of the component, gradually building a controlled metallic layer.
Other processes, such as electroless nickel plating, use a chemical reaction rather than an electrical current to create the deposit.
The exact process depends on several factors, including:
- The base metal being plated
- The required plating material
- The size and shape of the component
- The required coating thickness
- The component’s intended use
- The performance characteristics required
- Relevant industry standards and specifications
Correct surface preparation and process control are essential because the plated layer must adhere securely and perform consistently throughout the component’s working life.
Why Is Plating Used?
Plating allows engineers and manufacturers to change or enhance the surface properties of a component while retaining the characteristics of the underlying material.
A component might, for example, be manufactured from a material chosen for its strength, weight or cost, then plated with another metal to provide the surface properties its application requires.
Corrosion Resistance
Plating can protect the underlying metal against corrosion caused by moisture, chemicals and other environmental conditions.
Zinc plating is a common example. Zinc provides sacrificial protection, corroding preferentially to help protect the base metal beneath it.
Electrical Conductivity
Plating plays an important role in electrical and electronic applications.
Highly conductive metals such as silver and copper can be applied to components including busbars, contacts and connectors to provide the surface conductivity required for efficient electrical performance.
Wear Resistance
Certain plated finishes can provide a harder and more durable surface, helping components withstand friction, abrasion and repeated mechanical use.
Solderability
Tin plating and other suitable finishes can provide a solderable surface for electrical and electronic components while also protecting the underlying material against oxidation.
Improved Appearance
Plating can also change the appearance of a component, producing bright, smooth or decorative finishes. In industrial applications, however, the choice of plating is often primarily determined by the functional performance required.
What Metals Are Used for Plating?
Different plating metals provide different properties, so there is no single finish suitable for every component or application.
Silver Plating
Silver plating is particularly valuable for electrical applications because silver has the highest electrical conductivity of any metal.
It is commonly used for busbars, switchgear, connectors, contacts and other components where low electrical resistance and reliable current transfer are important.
Gold Plating
Gold plating combines excellent electrical conductivity with strong resistance to corrosion and oxidation.
It is frequently specified for electrical contacts, connectors and precision components where consistent performance and reliability are critical.
Nickel Plating
Nickel plating can provide corrosion resistance, hardness and improved wear performance. It can be used as a final finish or as an undercoat for another plating material.
Tin Plating
Tin plating provides good corrosion resistance and solderability alongside useful electrical properties.
Both bright tin plating and dull tin plating are available, with the appropriate choice depending on the component and its application.
Copper Plating
Copper plating offers excellent electrical and thermal conductivity.
Copper can be used as a functional finish in its own right or as an undercoat before subsequent plating. It can also help create a smooth surface for additional metal deposits.
Zinc Plating
Zinc plating is widely used to protect steel components against corrosion.
The zinc acts as a sacrificial layer, helping protect the underlying steel even if the plated surface becomes damaged.
Electroplating vs Electroless Plating
Although the terms plating and electroplating are sometimes used interchangeably, not every plating process uses electricity.
Electroplating
Electroplating uses an electrical current to deposit metal ions onto a component.
The component is immersed in an electrolytic solution containing ions of the plating metal. When current is applied, these ions are deposited onto its surface.
Silver, gold, copper, tin, nickel and zinc can all be applied using electroplating processes.
Electroless Plating
Electroless plating uses a controlled chemical reaction to deposit metal rather than an external electrical current.
One of the main advantages is its ability to produce a highly uniform coating, including across components with complex shapes and geometries.
Electroless nickel plating is one of the most widely used examples. For a closer look at how the two methods differ when plating with nickel, read our guide to electroless nickel plating vs electrolytic nickel plating.
What Materials Can Be Plated
A wide range of base metals can be used as substrates for industrial plating.
These include:
The plating processes available depend on the substrate because different metals have different surface characteristics and preparation requirements.
Aluminium, for example, is highly reactive and requires specialist pre-treatment before plating to ensure good adhesion.
Understanding both the substrate and the intended application is therefore an important part of specifying the correct plating process.
What Happens Before a Component Is Plated
Successful plating starts before the plating material itself is applied.
Components must be properly prepared to remove contaminants such as oils, grease, dirt and oxides. Contamination can prevent the plated metal from bonding correctly with the substrate, leading to poor adhesion or an inconsistent finish.
The preparation process varies according to the substrate and plating specification and may involve several stages of cleaning, degreasing and blasting, as well as rinsing and chemical treatment.
For some materials, additional pre-treatment is required to prepare the surface for plating.
For more information about preparing components for plating, read our guide to substrate degreasing and cleaning processes.
Rack Plating and Barrel Plating
The way components are handled during plating can also vary.
Rack Plating
With rack plating, individual components are secured to a conductive rack before being immersed in the plating solution.
This gives greater control over electrical contact and component positioning, making rack plating suitable for larger, delicate or more complex parts.
Barrel Plating
Barrel plating allows large quantities of smaller components to be processed together.
Parts are placed inside a rotating barrel that is immersed in the plating solution. This makes the process particularly efficient for high-volume batches of suitable components such as fasteners, pins and other small parts.
The best method depends on component geometry, finish requirements, production quantities and the level of control required. Find out more about Karas’ rack and barrel plating capabilities.
How Thick Is a Plated Coating?
The thickness of a plated coating can vary considerably according to the process and the component’s intended application.
The required thickness depends on factors including the plating material, operating environment and the performance required from the finished component. Some applications require only a very thin deposit, while others need a heavier build to provide the necessary corrosion protection, wear resistance or electrical performance.
Plating thickness also needs to be considered alongside component dimensions and tolerances, particularly where even small changes could affect fit or assembly.
Accurate process control and testing are therefore particularly important where components need to meet tight engineering tolerances or industry specifications.
For more detail on specifying the right coating thickness, read our guide to electroplating thickness.
Which Industries Use Plating?
Plating is used throughout modern manufacturing because it allows the surface performance of components to be engineered for specific operating conditions. Karas works with customers across a wide range of industry sectors.
Electrical and Electronics
Silver, tin, gold, nickel and copper plating are used across connectors, contacts, terminals, busbars, switchgear and other components within the electrical and electronics industries.
Automotive and Electrification
Plated components are used throughout the automotive industry for corrosion protection, electrical performance and durability. The growth of electrification has also increased the importance of plating for high-current electrical components and power distribution systems.
Aerospace and Defence
Energy and Power Generation
Plating supports reliable electrical connections and protects components used throughout the energy and power generation industries.
Rail and Transportation
Plated components are used across the rail and transportation industry where resistance to corrosion, wear and environmental exposure can be critical.
Medical
Specialist plated finishes are used for components and equipment within the medical industry where performance, reliability and appropriate material properties are essential.
Telecommunications
Gold, silver, tin and other finishes are used within the telecommunications industry on electrical contacts and connectors to help maintain reliable signal and electrical performance.
How Do You Choose the Right Plating Process?
Choosing a plating process starts with understanding what the finished component needs to do.
Important considerations can include:
- Base material
- Corrosion resistance
- Electrical conductivity
- Wear resistance
- Solderability
- Operating temperature
- Component geometry
- Required plating thickness
- Production volumes
- Environmental exposure
- Relevant technical or industry specifications
- Cost
In some applications, several plating materials may be technically suitable. The final choice then depends on the balance between performance, specification and cost.
This is why discussing the application as well as the required finish with an experienced plating specialist can be valuable, particularly for components with demanding or unusual requirements.
Metal Plating at Karas
Karas Plating provides an extensive range of electroplating, electroless plating and metal finishing processes for manufacturers and engineers across the UK.
Our plating processes include:
- Silver plating
- Gold plating
- Nickel plating
- Electroless nickel plating
- Bright tin plating
- Dull tin plating
- Copper plating
- Zinc plating and colour passivates
- Busbar plating
- Rack and barrel plating
With more than 70 years of plating experience, our team can advise on the most appropriate process for the substrate, application and performance requirements of your components.
Quality is controlled throughout the plating process, with plated deposits inspected and X-ray tested to ensure they meet the required specification. Karas operates to ISO 9001, ISO 14001 and ISO 45001 standards, supporting consistent quality, environmental responsibility and health and safety.
Need Advice on a Plating Project?
Choosing the correct plating process can have a significant impact on component performance, reliability and service life.
If you have a component that requires plating, or you are unsure which finish is best suited to your application, speak to the Karas Plating team. We can review your substrate, drawings, specifications and performance requirements and help identify an appropriate plating solution.
Contact Karas Plating today to discuss your requirements or request a quote.