Spraying process
Powder spraying process, also known as powder coating is developed rapidly in recent years a new coating process, the use of raw materials are plastic powder.

 As early as in the forty's some countries began to study the experiment, but progress is slow. Germany in 1954 to James polyethylene by fluidized bed coating 

method is successful, in 1962 France sames company invented the powder electrostatic spraying, powder coating began to officially adopted in production, in 

recent years due to the countries of the importance of environmental protection, on air, water and no pollution of powder coating, rapid development.

advantages

1, a coating can get thicker coating, such as coating 100~300 m coating, with a general ordinary solvent coating, about the need to coat 4~6 times, and

 the powder coating is a time to reach the thickness. The corrosion resistance of the coating is very good.

2, powder coating is solvent free, no waste pollution, improve working conditions and health.

3, the use of powder electrostatic spraying and other new technology, high efficiency, suitable for automatic assembly line coating; powder utilization rate is high, can be recycled.

4, in addition to a thermosetting epoxy, polyester, acrylic, there is still a large number of thermal plastic resistant grease as powder coatings, such as polyethylene, polypropylene,

polystyrene, fluorinated polyether, polyamide, polycarbonate, containing fluorine resin etc..

Powder coatings are used in the development of technology, which is widely used in the automotive industry, electrical insulation, corrosion resistance, chemical pumps, valves, cylinders, 

pipes, outdoor steel components, steel furniture, castings, etc..

Since the beginning of the sixty's, the experimental study of powder coating, and the application in production, development has been widely used.

Process introduction

It is composed of a porous separator and a container, and the container is divided into two parts.

The working process is this: below the clapboard is part of the container is to pass into the compressed air, compressed air through a porous partition

 board to make the powder without air flow of suspension, and roll in the upper portion of the vessel, showing "boiling" status. The preheating of th

e workpiece through the "boiling" of the powder area to achieve the coating effect. The preheating temperature of the workpiece can be slightly higher than the melting temperature of the powder.

In the last few years, some improvements have been made in the fluidized bed process and the combination of the electrostatic powder and the electrostatic powder coating has been obtained.

In order to get good results, we should pay attention to the following aspects:

Requirements of fluidized bed structure simple, smooth to avoid dead ends, best provided with a vibration device; a porous partition board in a fluidized bed, should have a certain pore size and density

 distribution; powder particle size by 50-150 mesh / grid mesh as well, nearly orbicular in shape ideal; powder coatings containing water requirements as low as possible, in order to avoid bad fluidization 

and coated bubbles; compressed air flow rate and flow must be adjusted to powder coatings stable fluidization and can not overflow, and compressed air shall be clean and dry

Flame spraying

In the oxygen acetylene flame, the powder is heated to a high temperature area of the gun at a speed of 50m/s, which is heated to become a molten or semi molten state, which is sprayed onto the surface

 of the heated surface until the desired thickness. Powder flame spray process is relatively simple, can be used for the surface of the coating, as well as mechanical wear repair work.

Hot melt coating

Folding electrostatic powder

This is one of the most important construction technology in the development of powder coating.

Basic principle:
A high-voltage corona discharge electric field is formed between the gun and workpiece, when a lot of powder particles is ejected from the spray gun nozzle through the discharge zone, will complement the electronic become negatively 

charged particles, in electrostatic attraction, are adsorbed onto positively charged workpiece up. "Same-sex repulsion" will happen, when is powder attached to a certain thickness, cannot absorb powder, so that each part of the powder

 layer of uniform thickness, and then the heating curing powder laminar flat become uniform film; electrostatic powder spraying process, the typical electrostatic powder spraying process are as follows: member, degreasing, cleaning, to rust,

 cleaning, phosphorization, cleaning, passivation, electrostatic powder spraying, curing, cooling and conditions; influence of electrostatic powder spray quality main factors.