After the powder coating application, the powder enters the curing oven and undergoes two key stages: agglomeration, and melting, leveling & spreading. A high-quality industrial curing oven plays a pivotal role in ensuring the uniformity, durability, and aesthetics of the powder coating finish, making it an indispensable equipment in the powder coating industry.

I. Agglomeration Stage

During the baking process in the curing oven, as the temperature rises, the surface of powder coating particles begins to melt, and the molten areas of adjacent particles then aggregate with each other. 1 to 3 minutes after entering the industrial curing oven, when the surface temperature of the workpiece reaches 40-60℃, the powder on the workpiece surface starts to gradually gather and become wetted. This stage lays the foundation for the subsequent melting and leveling process, and the stable temperature control of the curing oven is crucial to avoid uneven agglomeration.

II. Leveling, Melting Spreading & Curing Stage

1. Leveling Stage

3 to 7 minutes after entering the curing oven, when the temperature rises to 80-100℃, the leveling agent—with its low softening point—reduces the overall softening point of the powder coating system. This is a key advantage of incorporating functional additives in powder coating formulations used with curing ovens.

The leveling agent quickly migrates to the surface of the molten system, forming a molecular layer with locally uniform surface tension. Surface tension is the primary driving force for powder coating leveling, but there is a common misunderstanding that leveling agents increase surface tension—this is incorrect. For optimal leveling results, the curing oven’s temperature stability must be maintained to support the uniform migration of the leveling agent.

2. Melting Spreading Stage

At this stage, the entire powder coating system turns into a molten state. Since the leveling agent has already migrated to the surface of the molten coating, its wetting effect on the resin, fillers, and pigments inside the powder is insignificant. This stage is critical for achieving a smooth coating surface, and the performance of the curing oven directly impacts the melting efficiency.

As the temperature in the curing oven continues to rise, the viscosity of the powder coating drops sharply—meaning the driving forces for leveling and wetting far exceed the resistance caused by viscosity. Thus, this is the main stage for wetting and leveling of the powder coating.

Under the combined action of brighteners and leveling agents, the surface tension inside the molten coating decreases, enabling the resin to better wet the pigments and fillers. Additionally, volatile substances such as moisture inside the molten fluid are accelerated to escape from the surface—adding benzoin can further promote bubble rupture and escape. After escaping, the bubbles form a flat surface under the effect of surface tension, with the curing oven’s consistent temperature field ensuring uniform spreading.

3. Curing Stage

Under the high-temperature environment of the curing oven, the powder coating starts to cure, and the viscosity of the system gradually increases. With the surface tension remaining unchanged, the flow resistance rises rapidly, so little to no leveling occurs at this stage. The final curing effect depends on the curing oven’s precise temperature control and holding time, which are essential for enhancing the coating’s adhesion, corrosion resistance, and wear resistance—key performance indicators in industrial powder coating applications.

Investing in a high-performance curing oven is essential for optimizing the powder coating curing process. Our industrial curing ovens are designed to provide stable temperature control, uniform heat distribution, and efficient curing performance, ensuring consistent, high-quality powder coating finishes for various industrial workpieces. Whether for batch production or continuous processing, our curing ovens meet the rigorous demands of the modern powder coating industry.