Metal Brush Plating Technology

Metal brush plating technology
Metal brush plating is a surface repair and strengthening technology that eliminates the need for large plating tanks. Instead, a specialized brush plating pen contacts and moves relative to the workpiece surface, achieving localized electroplating. Its operating principle is similar to that of traditional electroplating, both based on electrolysis, but with more flexible equipment and operation. The brush plating pen acts as the anode, typically consisting of a conductive handle wrapped in a cotton sheath that absorbs the brush plating solution containing the metal ions to be plated. The workpiece to be plated acts as the cathode, connected to the negative terminal of a DC power supply. When the brush plating pen contacts and moves against the workpiece surface, current forms a circuit through the pen, the plating solution, and the workpiece. The metal ions in the plating solution are reduced and deposited on the workpiece surface, forming a coating. This technology is particularly suitable for the local repair of large, complex, or inconveniently disassembled parts, such as repairing worn machine tool guides and strengthening the tooth surfaces of large gears. It offers advantages such as flexible operation, high efficiency, and minimal thermal impact on the workpiece.

The metal brush plating process primarily includes surface pretreatment, brush plating the base layer, brush plating the working layer, and post-treatment. Surface pretreatment is crucial for ensuring coating quality and includes degreasing, rust removal, and activation. Degreasing can be performed using organic solvents or electrochemical degreasing to remove grease from the workpiece surface. Rust removal typically involves pickling or mechanical polishing to remove rust and scale. Activation involves using a specialized activation solution to remove residual oxide film, exposing the fresh metal surface and improving the adhesion between the coating and the substrate. Certain materials, such as aluminum alloys and stainless steel, require specialized pretreatment, such as zinc immersion for aluminum alloys, to improve coating adhesion.

The selection of the base layer for brush plating is crucial, as its primary function is to improve the bonding strength between the working layer and the substrate. Common base materials include nickel and copper. For example, nickel base layers offer excellent bonding and coverage, making them suitable for most metal substrates. Copper base layers are often used for brush plating of cast iron parts, effectively filling tiny pores on the substrate surface. The working layer is selected based on the part’s intended use. For example, if wear resistance is required, hard chromium or nickel-tungsten alloys can be chosen; if corrosion resistance is required, zinc-nickel alloys or tin-lead alloys can be chosen; and if dimensional repair is required, metals such as copper and iron, which are easy to deposit and have controllable thickness, can be chosen. During the brush plating process, the speed of the plating pen, the current density, and the amount of plating solution supplied must be controlled to ensure a uniform and dense coating and avoid defects such as pinholes and peeling.

Compared with traditional tank plating, metal brush plating technology has significant advantages. First, the equipment is simple and portable, and does not require a large electroplating tank, making it particularly suitable for on-site repair and local processing of large parts. Second, the process is flexible, and electroplating can be performed on specific parts of the parts as needed, reducing material waste. Third, the deposition speed is fast, and the current density of brush plating is usually higher than that of tank plating. The coating deposition rate can reach 0.01-0.1mm/min, which can quickly repair the dimensional error of parts. Finally, the thermal impact on the workpiece is small. The workpiece temperature during brush plating generally does not exceed 70°C, and will not change the microstructure and mechanical properties of the substrate. It is suitable for precision parts and parts after heat treatment.

Metal brush plating technology has a wide range of applications across the industrial sector, playing a particularly important role in equipment repair and remanufacturing. In the machinery manufacturing industry, it can be used to repair worn shaft journals, guide rails, bearing seats, and other components, restoring dimensional accuracy and performance, and extending equipment life. In the aerospace sector, it can be used to locally strengthen and repair critical components such as aircraft engine blades and landing gear, ensuring flight safety. In the power industry, it can be used to repair wear on motor rotors and turbine blades, reducing downtime and lowering repair costs. With technological advancements, metal brush plating technology continues to improve. The use of new brush plating solutions (such as environmentally friendly cyanide-free plating solutions) and automated brush plating equipment have further enhanced coating quality and production efficiency. In the future, with the rise of the remanufacturing industry, metal brush plating technology will play an even greater role in resource conservation and the circular economy, providing strong support for sustainable industrial development.