[Surface treatment] Barrel plating

Barrel plating is a well-established surface treatment process. It involves placing a fixed quantity of small metal or plastic parts into a specialized rotating drum, which is then placed in an electroplating tank. The rotation of the drum causes the workpieces to collide and conduct electricity, allowing the metal to be deposited on their surfaces. This technology is highly efficient and low-cost, making it ideal for the mass production of small hardware parts such as screws, nuts, rivets, and washers.

Barrel plating process (nickel plating on copper)

 Barrel plating processes are used for various materials, such as nickel plating on copper, iron, and stainless steel. Here, we'll use nickel plating on copper as an example to understand the process (as shown below). The process typically begins with degreasing the workpiece to remove dirt. To achieve better surface cleanliness, electrolytic degreasing is usually performed. Next, nickel plating begins.

The plating time depends on the desired film thickness; the workpiece is immersed in the plating solution. Once the preset film thickness is reached, the workpiece is removed and placed in a neutralization tank for passivation. Finally, it is rinsed and dried to complete the process.

The process may vary depending on the workpiece or material, but it generally follows the steps below.

Advantages and disadvantages of barrel plating

Advantages of barrel plating:

Cost and efficiency: Processes a large number of parts at once, resulting in high efficiency, reduced labor costs, and lower overall costs.

Suitable for batch production: Suitable for mass production of standardized small parts.

Easy operation: Small equipment footprint and low maintenance costs.

Uniformity (under certain conditions): With appropriate drum speeds, continuous tumbling of parts can achieve basic uniformity.

Disadvantages of barrel plating:

**Part damage:** Parts tumble and collide continuously inside the barrel, making it unsuitable for components with complex shapes or fine surfaces.

**Uneven plating:** Due to the less stable current density and cathode conductivity within the barrel compared to rack plating, the plating thickness may be uneven, and it is difficult to plate inside blind holes.

**Numerous limitations:** Not suitable for excessively large, lightweight, flat, or pore-prone parts.

**Low current efficiency:** Due to the barrel structure, current efficiency is low, and localized hydrogen evolution is common during plating, requiring frequent pH adjustments.

Summarize

Screws, nuts, washers, small hardware parts, electronic components and other related workpieces are suitable for barrel plating. However, if the workpiece has a complex structure, cannot have external damage on the surface, or has requirements for uniform film thickness, barrel plating is not suitable and other processes need to be evaluated.