Knowledge Hub
20/02/2024
Plating for CNC Machined Parts
What is Plating for CNC Machined Parts?
Plating is a surface finishing process for CNC machined parts.
Plating involves depositing a thin layer of metal on to the surface of a part through electroplating.
Plating can be done with various metals, including nickel, chrome, zinc, gold, and silver. The part to be plated is immersed in an electrolytic bath along with a metal salt solution, and a direct current is applied to initiate the deposition of the metal on to the part’s surface.
Plating can improve the durability, appearance, and functionality of CNC machined parts.
What is the Process for Plating a CNC Machined Part?
Plating a CNC machined part involves applying a protective or decorative layer of metal on the surface of the part. The process generally consists of the following steps:
- Preparing the surface: The CNC machined part is cleaned and prepared by removing any dirt, grease, or contaminants from the surface. This is done by using chemical cleaners, solvents, or ultrasonic cleaning methods.
- Surface activation: To ensure proper bonding of the plating material, the surface of the part needs to be activated. This is typically done by etching or treating the surface with a chemical solution, such as an acid or alkaline bath.
- Electroplating: The part is then immersed in an electrolyte solution containing metal ions of the desired plating material. The part acts as a cathode, while an anode made of the plating metal is also present in the solution. A direct electrical current is passed through the solution, causing the metal ions to be deposited on to the surface of the part. The plating metal may vary depending on the intended outcomes (i.e. corrosion resistance, conductivity, or aesthetics etc).
- Controlling plating thickness: The plating thickness can be controlled by adjusting the current density, plating time, and other variables. This ensures a uniform and desired thickness across the surface of the part.
- Post-plating treatments: After the desired plating thickness is achieved, the part may undergo additional processes to enhance the plating’s properties. This may include rinsing to remove any residual plating solution, heat treatments for improved adhesion and hardness, or applying a protective coating such as a clear lacquer.
- Quality control: Finally, the plated part undergoes quality control measures to ensure it meets the desired specifications. This can involve checking plating thickness, adhesion, appearance, and any functional requirements.
It is important to note that the plating process may vary depending on the type of plating material, the part’s material, and the intended application. Different plating techniques, such as electroless plating or electrochemical deposition, may be used in certain cases.
What are the Different Types of Plating Processes?
There are several types of plating options for CNC machined parts, including:
Electroplating: This is the most common type of plating process, which involves depositing a thin layer of metal on to the surface of the part. It provides increased corrosion resistance, improved wear resistance, and enhanced aesthetic appearance.
Anodizing: Anodizing is an electrochemical process used to treat aluminium and its alloys. It forms a durable oxide layer on the surface of the part, improving corrosion resistance and providing a decorative finish.
Powder coating: Powder coating involves applying a dry coloured powder to the surface of the part, which is then heated to create a durable and attractive finish. It provides excellent resistance to corrosion, impact, and chemicals.
Nickel plating: Nickel plating offers high corrosion resistance and provides a smooth, glossy finish. It can be used as an undercoat for other platings, or as a standalone coating.
Zinc plating: Zinc plating, also known as galvanizing, is a process in which a protective layer of zinc is applied to the part. It offers corrosion resistance and can also act as a sacrificial coating to protect the underlying metal.
Chrome plating: Chrome plating is used to provide a high level of hardness, corrosion resistance, and reflectivity. It is commonly used for decorative purposes, especially on automotive parts.
Tin plating: Tin plating is used to increase corrosion resistance, provide solderability, and improve the part’s appearance. It is commonly used on electronic components and food contact surfaces.
The Benefits of Plating a CNC Machined Part
There are several benefits of plating a CNC machined part. Let’s take a closer look at some of these benefits in more detail:
Improved surface finish: Plating can enhance the appearance and aesthetics of a CNC machined part by providing a smooth and polished surface.
Increased corrosion resistance: Plating can provide a protective layer on the surface of the machined part, preventing it from being affected by environmental factors like moisture, chemicals, or oxidation.
Enhanced durability: Plating can improve the mechanical properties of the part, making it more resistant to wear, abrasion, and corrosion. This can extend the lifespan of the part and reduce the need for frequent replacements.
Better electrical conductivity: Plating can also enhance the electrical conductivity of the part, making it suitable for applications that require good electrical contact, such as electronics or electrical connectors.
Improved solderability: Plated surfaces are often more compatible with soldering processes, making it easier to join the machined part with other components in an assembly.
Enhanced adhesion: Plated surfaces generally have better adhesion properties, allowing for improved bonding with paints, adhesives, or other coatings if required.
Customisable appearance: Plating can be done with various materials and finishes, allowing for customisation of the part to meet specific design or aesthetic requirements.
Reduced friction and wear: Plated surfaces can have lower friction coefficients, which can help to reduce wear and increase the efficiency of moving parts in mechanical assemblies.
Regulatory compliance: Plating can be done with materials that comply with specific industry standards or regulations, ensuring that the machined part meets the necessary requirements for its intended application.
Overall, plating a CNC machined part can provide numerous functional and aesthetic benefits, making it a valuable finishing process for many applications.
