How to improve corner coverage and reduce missed areas in the surface treatment of complex structural parts using plastic spraying electrophoresis?
Publish Time: 2026-05-26
In industrial manufacturing and surface treatment processes, plastic spraying electrophoresis is widely used in products with relatively moderate requirements for appearance and protection, such as shelves, appliance housings, and building profiles, due to its moderate cost, stable process, and strong adaptability. However, in the surface treatment of complex structural parts, especially on workpieces with deep cavities, corners, grooves, or multi-layered curved surfaces, uneven corner coverage and missed areas remain common problems. These issues not only affect the consistency of appearance but may also weaken local protective performance.
1. Optimize Electric Field Distribution to Improve Corner Deposition Efficiency
The core principle of electrophoretic spraying is to use an electric field to drive paint particles to deposit on the workpiece surface. Therefore, the uniformity of the electric field distribution directly affects the coating coverage. In complex structural parts, due to the "electric field shielding effect" in the corner areas, insufficient paint deposition can easily occur, resulting in missed areas. To improve this problem, the electric field distribution can be made more uniform by optimizing the electrode layout and tooling fixture design. For example, adding auxiliary electrodes or adjusting the conductive path of the hanger in key areas can effectively enhance the electric field strength at corners, thereby improving the coating's adsorption capacity and enabling more uniform coverage in complex structures.
2. Adjusting Process Parameters to Improve Coating Flow and Coverage
Besides the electric field factor, the flowability and deposition behavior of the electrophoretic solution itself directly affect the corner coverage effect. In the processing of complex structural parts, the uniformity of coating distribution can be improved by reasonably adjusting key process parameters such as voltage, time, and bath concentration. For example, appropriately increasing the initial voltage helps enhance the migration speed of coating particles to the workpiece surface, thereby improving the initial coverage rate of corner areas; while segmented voltage control can ensure overall uniformity while avoiding local over-thickness or sagging. Furthermore, optimizing the bath flow circulation system can also reduce uneven coating deposition in dead corner areas.
3. Strengthening Pretreatment Processes to Improve Surface Wettability
The pretreatment process is a crucial foundational step affecting the adhesion of electrophoretic coatings. If the workpiece surface contains oil, oxide layers, or microparticle contaminants, it will directly affect the coating's adhesion capacity in corner areas, leading to localized missed coatings. Therefore, pre-treatment with enhanced degreasing, pickling, or surface activation can significantly improve the surface wettability of plastic or metal substrates, allowing electrophoretic coatings to more evenly cover complex structural areas. Simultaneously, uniform pretreatment reduces surface tension differences, resulting in more stable coating adhesion at corners and edges.
4. Optimizing Structural Design and Tooling Layout to Reduce Dead Zones
During the product design phase, overly complex structures or the presence of numerous enclosed dead zones increase the difficulty of coating. Therefore, optimizing the structural design—such as increasing drainage holes, reducing the proportion of deep and narrow grooves, or improving curved surface transitions—can effectively reduce areas difficult for the coating to reach during electrophoresis. Furthermore, in tooling design, adjusting the workpiece suspension angle appropriately ensures that critical corner areas are fully exposed to the electric field and coating flow path, significantly improving coverage and reducing missed areas from the outset.
In summary, to improve edge and corner coverage and reduce missed areas in the surface treatment of complex structural components, plastic spraying electrophoresis requires coordinated optimization from multiple aspects, including electric field distribution optimization, process parameter adjustment, pretreatment enhancement, and structural and tooling design improvements. This systematic process improvement not only enhances coating uniformity and appearance quality but also strengthens overall protective performance, enabling electrophoretic spraying to play a more stable and reliable role in the manufacturing of complex structures.
