Powder electrostatic coating is a common coating technology widely used in automobile manufacturing, metal processing, furniture manufacturing and construction.

During the powder electrostatic coating process, powder particles are adsorbed onto the surface of the workpiece by electrostatic force.

This process involves a number of stages, and this article will delve into the three key stages of powder adsorption onto the workpiece.

Stage 1: Charge transfer

The first key stage of powder electrostatic coating is the charge transfer stage. In this stage, the coating powder is electrically charged, usually through the charge gun of the coating equipment. The charge gun will apply a positive charge to the powder particles by charge transfer so that they carry the same charge. The process usually consists of the following steps:

1.1 Supply of coating powder

The coating powder is usually stored in a special container and then delivered to the coating equipment via a coating supply system. This supply system can be either liquefied powder or powder solids, depending on the needs of the application.

1.2 Role of the Charge Gun

The charge gun is one of the core components of the powder electrostatic coating equipment. It consists of a nozzle through which the coating powder is released and charged by charge transfer. Typically, the charge gun uses a high voltage electric field to drive the powder particles and bring them to the surface of the workpiece.

1.3 Charge Transfer

The powder particles released by the charge gun through the nozzle interact with the electric field and acquire a charge. This causes the powder particles to carry the same charge, usually a negative charge. These charged powder particles then proceed to the next adsorption stage.

Stage 2: Powder Adsorption

After the charge transfer stage, the powder particles carry a charge into the powder adsorption stage. This stage involves the adsorption of the charged powder particles onto the surface of the workpiece. The following are the key steps in the powder adsorption stage:

2.1 Electrostatic attraction

Charged powder particles are attracted to the surface of the workpiece by electrostatic forces. Usually, the surface of the workpiece is first grounded, which gives the powder particles a negative charge that is attracted to the positive charge on the surface of the workpiece. This electrostatic attraction causes the powder particles to be evenly distributed along the surface of the workpiece, forming a thin film.

2.2 Preparation of the workpiece for coating

Prior to painting, the surface of the workpiece usually needs to be prepared to ensure that the coating will adhere evenly and remain durable. This may include cleaning, removal of grease, rust and other dirt, and necessary surface preparation such as phosphating or sandblasting.

2.3 The Spraying Process

Once the powder particles have been adsorbed onto the surface of the workpiece, the spraying process begins. The operator uses spraying equipment to evenly spray the powder particles onto the workpiece, ensuring an even distribution of the coating. This step usually requires skill and experience to ensure the quality of the coating.

 

Stage 3: Curing and Finishing

The third key stage of powder electrostatic coating is the curing and finishing stage. In this stage, the powder particles that have been adsorbed onto the surface of the workpiece need to be cured to form a solid coating. The following are the main steps in this phase:

3.1 Drying and warming

Typically, the coating powder needs to be dried and warmed up on the workpiece to allow it to cure. This can be achieved by placing the workpiece in a constant temperature room or by using an oven. The purpose of warming is to melt and fuse the coating powder to form a solid coating.

3.2 Curing

During the warming process, the coating powder cures to form a solid coating. The curing time and temperature usually depends on the type and thickness of coating used. Once curing is complete, the coating will have the desired hardness, durability and appearance characteristics.

3.3 Surface preparation (optional)

Depending on the coating requirements, the surface of the workpiece may require further treatment such as polishing, grinding or varnishing to achieve the desired appearance and quality standards.

Conclusion

Powder electrostatic coating is an efficient, durable and environmentally friendly coating technique that involves a number of key stages including charge transfer, powder adsorption and curing and finishing.

Understanding the principles and steps involved in these phases is critical to obtaining high quality coating results. With proper handling and control, powder electrostatic coating can achieve a uniform finish, excellent durability and a wide range of cosmetic effects, and is therefore widely used in several industrial sectors.