[China Aluminum Network] Effect of Particle Size of Powder Coatings on Powder Properties
The adsorption of powder coating particles on the surface of the workpiece depends on the flow rate and the amount of charge. According to Coulomb's law, the charge of a particle is related to the applied electric field, particle diameter, and the dielectric constant of the particle. In a certain period of time, the charge amount of powder coating particles is expressed as follows:
It can be seen from Figure 1 that the charge of the powder is proportional to the size of the powder particle size, increase the particle size of the powder, the charge amount of the powder increases, the powder rate increases; on the contrary, reducing the particle size of the powder, reducing the powder charge, The powder rate dropped. However, in the case of large particle size particles, the leveling of the coating film is not good, and the surface of the coating or the inside of the coating is likely to have voids. After the heat is solidified, the air in the middle is released, and “pinholes†are generated. Therefore, controlling the particle diameter of the powder is controlling the powder. One of the key issues of quality
The technical department of Lai Si based on a large number of chart data analysis for powder coatings suitable for electrostatic spraying, to control the particle size of D50 in the 25-35μm
Control of Powder Coating Particle Size in Production
From the process of smashing to packaging, the specific structure of a grinder, such as the ring gear, grinding disc, and pins, is fixed, including the length and length of the pipeline, the matching of the motor, the area of ​​the filter bag, the speed of the main grinding, etc. And so on, all equipment manufacturers need to design, verify and improve. We focus on the control of the powder particle size of the extruded pellets into finished products, and the process of adjusting the control parameters through inspection and recording. In the actual control process, four variables can be adjusted: feed amount, sub-mill speed, fan air flow, and pulse interval time. What is worth mentioning is the mesh number of the screen. It cannot determine the fineness of the powder particles. It merely removes particles above this mesh number. This is what we often say. The screen is fine and our powder is not fine.
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