Spraying various coatings on the product surface is one of the most important surface treatment processes, which can not only make the product look good, but also protect the product matrix. Among them, plastic spraying and paint spraying are two widely used spraying processes. If there is any difference between them, I believe many people don’t understand it, and even some people think it’s just a different name for the same process. In fact, they are two different processes, with different equipment and process flow. In fact, whether it’s plastic spraying or spray painting, they all belong to spray painting. If you understand plastic spraying and spray painting respectively, you can know the difference between them. First, let’s look at the simpler painting.

 

Painting

Spray painting is a simple and widely used surface treatment process, which is to put the paint into the container, pressurize it with machinery and equipment, and spray it on the product in the form of fog to form a layer of the paint film. Spray painting is widely used in ships, locomotives, bridges, machinery and other fields.

The main function of painting is to protect products or semi-finished products from rust and corrosion, and also to play a decorative role, making products look more beautiful.

 

Classification and characteristics of painting

According to the operation mode, painting can be divided into manual painting and automatic painting.

Manual spray painting refers to workers holding a spray gun to spray products according to the shape of the workpiece.

The advantages are flexible and convenient operation, suitable for products of different environments, shapes and sizes, simple equipment and low energy consumption;

The disadvantages are low production efficiency, unstable spraying quality, high labor intensity of workers, easy to be polluted by paint mist, and poor working conditions.

Automatic spray painting is the use of mechanically operated spray guns to spray products.

The advantages are high productivity, stable spraying quality and good working conditions for workers.

The disadvantage is that the equipment is expensive and the structure of the equipment is complex.

Painting can also be divided into air painting and high-pressure airless painting.

Air spray painting uses a spray gun as a tool, and uses the air flow of compressed air to disperse the paint, atomize it, and spray it onto the product surface to form a paint film.

Air spray painting has the advantages of simple equipment and dense coating; However, air spray painting will also occur. During the spray painting process, a large number of paint mist will be generated, which will pollute the air, and the paint loss is large. The moisture and other impurities in the compressed air are easy to mix into the paint flow, and the treatment is not clean, which will affect the quality of the coating.

Air spray painting is widely used in manual spray painting with large painting area and complex workpiece shape. Due to the large amount of paint mist generated during the painting process, in order to limit the pollution of paint mist to the environment.

High pressure airless spray painting is to use the high-pressure pump in the closed container to pressurize the paint and spray it from the spray gun. Due to the sudden drop of pressure, it will immediately expand and atomize violently, and spray it on the surface of the workpiece to form a paint film.

High pressure airless spray painting has the advantages of high productivity, less paint mist, low air pollution, good working conditions and strong adhesion to the paint film. Because there is no impurity such as water and oil mixed in the paint flow, the protective performance of the coating is good. High pressure airless spray painting also has the disadvantages of complex equipment structure, less uniform coating than air spray painting, and poor decoration.

High pressure airless painting is suitable for painting small products. In order to improve sanitary conditions, high pressure airless painting should be carried out in the paint booth.

 

Painting process flow

The product should also be treated before painting. The surface of the product should be cleaned by derusting, degreasing and other methods, so that the paint coating will be more firm.

After treatment, the surface of the product should be cleaned. After natural drying, it can be painted on the product.

Paint spraying includes directly spraying a layer of paint, or repeatedly painting for 2-3 times in order to obtain a dense and solid paint layer. In this way, the first painting is also called primer, and the next painting should be carried out after grinding.

 

Spray plastic

Compared with painting, plastic spraying is more complex. It is a process that directly sprays paint powder on products through equipment, so as to play a protective and decorative role. Plastic spraying is usually also called electrostatic powder spraying.

Plastic spraying is a widely used metal surface treatment technology, which is widely used in hardware, home decoration, building materials and other fields.

 

Principle of plastic spraying

In the process of plastic spraying, the powder coating in the container is sent to the nozzle of the spray gun by compressed air, and high-voltage static electricity will be generated at the front end of the nozzle, and an electrostatic field will be formed.

When the coating powder passes through this electrostatic field, it will discharge them, and finally each powder will become a charged coating ion. Under the action of electrostatic force, when it is sprayed, it will be attracted by products with opposite polarity, so as to be adsorbed on the product surface.

When the coating powder accumulates more and more, the charge will also accumulate and become more. When it reaches a certain thickness, the charged powder will be repelled by the charged powder covered on the product, and the coating powder will no longer accumulate continuously.

 

Characteristics of plastic spraying

Spray can directly use paint powder, which does not need to be diluted with liquid, and does little harm to the environment and human body.

The quality of the coating after electrostatic spraying is very good, and the adhesion is also strong; The technical requirements for workers are also relatively low, the curing time is short, and there will be no liquid sagging and many other advantages.

However, plastic spraying also has the disadvantages of difficult surface repair and high cost.

 

Process flow of plastic spraying

Like other surface treatment processes, the product also needs to be treated before plastic spraying to make the surface of the product clean before plastic spraying.

Because the spraying process directly sprays the coating powder on the product, the adsorption force is not very strong at this time, so an important step is high temperature curing.

By putting the coated product into an oven at a certain temperature, under the action of high temperature, the coating powder will melt and level itself, and finally form a dense and solid plastic spraying layer after curing.

 

Difference between painting and plastic spraying

By introducing plastic spraying and painting respectively, we can know the difference between them.

The leveling of spray painting is better than that of plastic spraying, because the molecular structure of additives and solvents used in spray painting will help the leveling, and these ingredients are not found in plastic spraying.

Painting can be repaired in a small area, but plastic spraying can’t, and the flexibility of painting is better than plastic spraying, so painting can be bent in a small size.

Painting has rich decoration and fast delivery time. It can be customized or produced in small batches.

Plastic spraying must be baked at high temperature, so the adhesion will be better, but there will be requirements for the size of the product, which is too large to be put into the oven, while painting does not need to have size requirements for the product, and large-area spraying construction can be carried out.