Powder coating baking line

Fluidized bed immersion coating method is also known as fluidized bed coating method or filling bed method. Place the powder coating into a fluidized bed with a porous plate as the bottom plate and pump in compressed air or inert gas. The powder coating will rise through the porous plate and become in a flowing state. When the coated object preheated to a temperature higher than the melting temperature of the coating is immersed in the fluidized bed, the powder coating in contact with its surface becomes semi molten or molten, forming a coating, which is then subjected to post heating to complete the coating treatment.
The factors affecting coating in fluidized bed immersion method include preheating temperature, immersion time, shape and heat capacity of the coating object, particle size (80-150 μ m) and melting point of the coating, etc. However, the factor determining the thickness of the coating is immersion time, usually 5-20 seconds.

1、 Example of processing conditions for fluidized impregnation coating:

2、 The characteristics of the process method are as follows:
1. A thick film of 250-1500 μ m can be obtained by secondary coating.
2. Less paint loss.
3. No need for recycling equipment or spray booth.
4. The equipment is simple and inexpensive.
5. Must be preheated.
6. The size and shape of the painted object are limited.
7. Even with a small amount of coating, a fixed quantity of paint is required.

3、 Powder soaking process flow:

Workpiece → Surface treatment → Preheating → Powder impregnation → Plasticization → Cooling

1. Powder dipping equipment: mainly composed of powder dipping box, operating room, pneumatic control system, preheating furnace, curing furnace and other equipment.
2. Powder immersion box: The size of the powder immersion box is related to the size of the workpiece being immersed, and is divided into an upper box and a lower box. The upper box is the powder box and the lower box is the air chamber. The material is made of stainless steel plate, with a microporous plate in between.
3. Pneumatic control system: composed of compressed air pipeline, pressure regulating valve, oil mist device, filter, valve, lifting cylinder, and foot operated pneumatic switch. The lifting cylinder will drive the workpiece to immerse in the powder immersion box, and manually control the workpiece to quickly rise and blow off excess powder on the workpiece with compressed air. The surface temperature of each workpiece should be measured during powder coating, and only workpieces that meet the temperature requirements can be subjected to powder coating.

During fluidized bed plastic immersion, the required coating is obtained by relying on the heat capacity of the workpiece to deposit the powder plastic. The preheating temperature of the workpiece is a key factor determining the thickness and quality of the coating. The preheating temperature of the workpiece should generally be slightly higher than the melting temperature of the powder plastic. If the preheating temperature is too high, it will not only cause the coating to be too thick and produce sagging defects, but also lead to the cracking of the polymer resin in the plastic, the generation of bubbles, and even yellowing or burning; If the preheating temperature of the workpiece is too low, the deposited powder will be insufficient, the coating will be too thin, and there will be a rough surface or even incomplete coating, which will not achieve the purpose of powder immersion.