Composition of pre-painting equipment


Chuangzhi Coating

Before painting, remove all kinds of oil stains (such as lubricating oil, emulsion, grease, sweat, etc.) and dust on the surface of the coated object, and the cleaning process to make the coated surface clean is an indispensable process before the coating process. So, what equipment are needed in the pre-painting process? Let me give you a brief introduction!

1. Pretreatment tanks, transfer tanks and chambers

A closed dust-proof channel (also called a chamber body) is provided on each process tank. The chamber body can generally be made of stainless steel or galvanized steel, preferably made of stainless steel. If ordinary carbon structural steel is used, it must be Apply epoxy coating to meet the requirements of anti-corrosion. There are glass windows, lighting devices and access doors for personnel in and out of the room.

2. Circulatory system

All immersion tanks should be equipped with circulating stirring pipelines to continuously update the bath fluid in contact with the workpiece surface, thereby accelerating the chemical reaction speed of the workpiece surface, shortening the process time and improving the quality of pretreatment. The number of circulation of the tank liquid can generally be 1-3 times / h, and the flow rate of the circulation pump is selected according to this. The pipe diameter is selected based on the calculated flow velocity of the pipe flow.

3. Jetting system

All spray cleaning processes use a water pump to spray the tank liquid onto the surface of the workpiece. With the help of mechanical scouring, the chemical reaction speed on the surface of the workpiece is accelerated, the process time is shortened, and the production efficiency of pretreatment is improved. 


The volume of the spray washing tank is generally small, the feeding amount is small at one time, and the equipment covers a small area. Outlet ends of all immersion tanks should also be provided with outflow jet lines, which can further improve the cleaning effect of workpiece pretreatment. The main types of nozzles used in the pretreatment electrophoresis production line are spraying and stirring.

4. Temperature control system

Composition of pre-painting equipment

Tank temperature is one of the important parameters affecting the quality of pretreatment. Different tank fluids require different working temperatures. Only by controlling the temperature within the required range can the processing effect of each tank fluid and the guarantee of the workpiece be fully exerted. Quality stability. The temperature control method is divided into manual control and automatic control. 


Most of the current coating production lines use automatic temperature control. The pre-treatment production line is basically in the form of heating, and the automatic control valve is used for temperature control. The heating method is different according to the energy used, and it is divided into three forms: direct heating inside the tank, indirect heating inside the tank, and indirect heating outside the tank. The pretreatment electrophoresis production line mainly uses plate heat exchangers and corrugated plate heat exchangers.

5. Iron powder removal system

The iron powder removal system is usually set in the first or two steps of the pre-treatment production line (usually pre-degreasing and degreasing steps). When the workpiece enters the pre-treatment equipment, the surface and interior of the workpiece may have a lot of Impurities such as iron powder, iron filings, sand and dust, most of the impurities will remain in the bath of the first and second processes after cleaning. 


In order to separate these impurities from the bath, the bath will be extended. Liquid life and renewal cycle, set up iron powder removal system is a very effective method. At present, the more popular method is to use a suspension separator + a paper bag filter for separation. The device has high efficiency and good removal effect, and the obtained iron powder has a high drying type, and can also effectively remove solid particles other than iron powder.

6. Oil-water separation

After a long-term production of the degreasing tank liquid, a large amount of grease (brought by the workpiece) will be accumulated in the tank and stay in the tank. When the concentration is increased to a certain extent, the degreasing effect will be seriously affected, and the workpiece processing quality will be affected. Frequent tank replacement will result in waste and a large number of sewage treatment problems. It is necessary to set up an oil-water separation system to remove grease in the degreasing tank. 


At present, there are many forms and types of oil-water separation, such as: adsorption degreasing device, ultrafiltration degreasing, hot oil separator, centrifugal separation, standing method, inclined plate method, etc. However, under normal circumstances, it is difficult to achieve the ideal degreasing effect by simply using a certain type of oil-water separation equipment, because the grease in the degreasing tank is difficult to be smoothly collected into the oil-water separation equipment. An oil-water separation auxiliary system should be set up according to the conditions of different production lines, combined with special oil-water separation equipment, to achieve a better effect of removing oil pollution.

7. Phosphate slag removal

Phosphating is a chemical reaction. With the formation of phosphating film, phosphating sediment is also generated, which is inevitable. Phosphating slag is harmful to the quality of the phosphating film of the workpiece. When the content of the phosphating slag is too high in the solution, it will adhere to the workpiece and affect the performance of the coating film. At the same time, for the spray system, too much sediment can easily cause nozzle clogging, which will cause insufficient treatment and rust. 


Therefore, it is required that the content of phosphating slag in the solution does not exceed a certain amount. At present, there are many forms and equipment used in phosphating slag removal, such as: inclined plate sedimentation, belt filtration, hydrocyclone separation, plate and frame filter press, vacuum filter, fully automatic dewatering filter press and so on. Due to the high degree of automation of the automatic dehydration filter press, the dehydration effect of the phosphating slag is good, and it is environmentally friendly. It is widely used in coating lines with a certain scale.

8. Pickling unit for phosphating heat exchanger

After long-term use of the heat exchanger, the phosphated slag will condense on the inner surface of the heat exchanger, reducing the heat exchange efficiency of the heat exchanger. The pickling device is used to regularly clean the inner wall of the phosphating heat exchanger to remove scale to ensure the thermal efficiency of the heat exchanger. It is mainly composed of pickling tank, pickling pump and circulation pipeline. Connected to the entrance and exit of the phosphating solution passage of the heat exchanger, generally use nitric acid cleaning or phosphoric acid cleaning.

9. Rehydration system

With the progress of production, the active ingredients of each medicine tank liquid in the pretreatment are continuously consumed and need to be added. According to the coating area, production situation and actual measurement results, the corresponding replenishment amount and replenishment cycle are given. The frequency of manual replenishment is limited, and the concentration curve obtained must inevitably fluctuate greatly. The concentration varies greatly at different times, resulting in unstable quality. For this reason, it is necessary to use an automatic addition method to maintain stable quality.


At present, the rehydration system is applied more frequently, such as regular quantitative replenishment and continuous replenishment along the production line. In large-scale production lines, continuous replenishment is usually adopted, which can ensure the stability of the components of each tank liquid to ensure the stability of product quality.

10. Tank liquid transfer system

The tank fluid transfer system is to transfer the working tank fluid to the transfer tank through a dedicated pipeline system when the degreasing or phosphating tank needs overhaul and maintenance. After the maintenance is completed, the working tank fluid is returned to the working tanks. system.

       The transfer tank should be installed as close to the work tank as possible according to the situation of the factory to shorten the connecting pipeline between the work tank and the transfer tank. The transfer system should be designed to ensure that the tank liquid is transferred cleanly within a short period of time. See the schematic diagram for the direction and function of the pipelines of each degreasing and phosphating system.

11. Supply and exhaust system

An air-sealing device needs to be provided at the inlet end of the pre-treatment to prevent the overflow of water vapor to the workshop, to prevent the workshop from being corroded, forming a source of pollution, and affecting painting construction operations. The degreasing process is provided with exhaust air to prevent steam from escaping. Supply air is provided before phosphating to close the phosphating area to protect the workpiece. 


Set exhaust air after phosphating to avoid phosphating steam from entering the subsequent stage of washing, which will affect the quality of the workpiece. Centrifugal fans and galvanized pipes are generally used. Stainless steel fans and stainless steel pipes can be used in places with higher requirements. The pre-treatment electrophoresis production line mainly includes two types of axial flow fans and centrifugal fans, and axial flow fans are rarely used because of their small heads and often unsatisfactory use. Centrifugal fans with complete specifications can meet various supply and exhaust requirements. It is the main fan type.

12. Room, platform and other auxiliary equipment

The main body of the chamber plays a role of sealing, ensuring that the production of the workpiece is in a dust-free state, and at the same time preventing the spray water from overflowing. The room is generally equipped with observation windows and lighting to observe the internal conditions. The platform is mainly used for placing equipment and operator inspections. In addition, the pre-treatment system still has some auxiliary equipment such as eye wash, pump shaft seal system, pressure discharge system, etc., which are set according to different needs.


The above is the relevant content about "composition of pre-treatment equipment". The information was provided by Guangdong Chuangzhi, a 25-year-old coating production line manufacturer. For more information about the coating production line, please follow us for updates! Watch more videos

Composition of pre-painting equipment

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