Is plastic spraying electrophoresis suitable for corrosion protection of large metal structures?
Publish Time: 2025-11-04
In industrial manufacturing and infrastructure construction, large metal structures such as shelves, workbenches, storage frames, building profiles, or outdoor equipment supports are exposed to humid, dusty, and even corrosive environments for extended periods, creating a dual demand for durable and economical surface protection. For these applications, "plastic spraying" and "electrophoresis" are often mentioned, but it's important to clarify that plastic spraying usually refers to powder coating on metal workpieces (although the names are easily confused), while electrophoresis is a completely different coating technology. While offering superior performance, it is less commonly used for ultra-large workpieces due to limitations in tank size and cost.
Powder coating uses electrostatic adsorption to uniformly adhere thermosetting or thermoplastic powders to the metal surface, followed by high-temperature curing to form a dense coating. This process is solvent-free, environmentally friendly, and produces a thicker coating that effectively isolates moisture and oxygen, providing good basic corrosion protection. For large, relatively simple, and low-precision metal components, such as warehouse shelves, workshop workbenches, or building supports, powder coating exhibits significant advantages. Its equipment investment is moderate, production lines can be flexibly arranged, and even on-site touch-up coating is supported; a wide range of colors are available to meet marking or aesthetic needs; more importantly, the coating has a certain degree of toughness, able to withstand mechanical stresses from handling and impacts without easily peeling off. These characteristics make it the mainstream choice for corrosion protection of large metal structures.
In contrast, electrophoresis coating relies on the complete immersion of the workpiece in an electrophoresis tank. Under the influence of an electric field, paint particles are uniformly deposited on all conductive surfaces, including areas difficult to cover with traditional spraying, such as cavities, welds, and grooves. Its coating is extremely thin yet dense, with strong adhesion and corrosion resistance far exceeding that of ordinary spraying, making it widely used in high-requirement fields such as automotive bodies and precision machinery. However, the electrophoresis process has a natural limitation on workpiece size—it must be able to fit into the electrophoresis tank. For shelving beams or large steel structures that are several meters long, constructing matching giant electrophoresis tanks is not only costly but also energy-intensive and complex to maintain. Therefore, although electrophoresis offers superior corrosion resistance, it is often impractical in the real-world application of large metal structures.
Furthermore, large structures typically have high tolerances for dimensional tolerances. While thick powder coatings cannot guarantee micron-level precision, they effectively conceal minor imperfections on the substrate surface, improving the overall appearance. The high precision and uniformity sought by electrophoresis are, in fact, excessive in the context of large, less demanding applications.
Of course, if a large structure is constructed from multiple small to medium-sized welded components, electrophoresis can be performed on individual components before assembly. However, this approach is complex, leaves weak points at the weld seams, and significantly increases costs, making it only suitable for special applications with extreme corrosion resistance requirements.
In conclusion, powder coating (often mistakenly referred to as "plastic spraying") is a practical choice for corrosion protection of large metal structures due to its advantages such as strong process adaptability, controllable cost, and corrosion resistance that meets conventional requirements. While electrophoresis offers superior performance, its equipment and size limitations make it difficult to scale up for truly "large" applications. Neither is inherently superior; rather, they each have their own suitable applications. In engineering practice, the key to selection lies in balancing protection levels, structural dimensions, cost budget, and production efficiency—ensuring the right process protects the right structure.
