Routine maintenance of electrophoresis equipment

Cathodic electrophoresis system is generally composed of circulation system, temperature control system, anode system, ultrafiltration system and tank. The maintenance of electrophoresis equipment is an important guarantee for the normal and sustainable production of electrophoresis, and electrophoresis companies should make maintenance plans for equipment.

1. Circulatory system

1.1 Main functions of circular mixing:

(a) To keep the tank liquid evenly mixed and to prevent pigment from settling in the tank or on the horizontal surface of the coated material.

(b) The tank is circulated through a filter to remove granular dust and oil from the tank.

(c) Maintain the uniform temperature of the tank and the components of the paint.

(d) Timely removal of gases generated on the surface of the workpiece (or plate) during electrophoresis.

1.2 The electrophoresis tank must ensure that the circulating amount of the tank liquid is at least 4 times the liquid volume of the tank /h, and insufficient circulating amount may cause deposition at the bottom of the tank and deposition on the surface of the workpiece; At the same time, ensure that there is no dead injection Angle at the bottom of the groove.

1.3 The circulating system usually contains a swimming paint filter, which needs to ensure proper filtration accuracy: good filtration can ensure that the coating film is free of particles and impurities dropped by the workpiece during the work.

1.4 Maintenance of the main slot circulation system:

(a) During production and non-production, the operation of the circulating pump should be checked regularly (per shift), and abnormal maintenance should be handled in time.

(b) Check the tank liquid flow rate every day, when the flow rate is reduced, the circulation pump and circulation pipeline should be checked in time, whether the pipeline is blocked or the valve is not opened normally; If the new pump needs to pay attention to the power of the pump and whether the pump is running forward. Check whether the nozzle has fallen off.

(c) Regular cleaning and replacement. For the electrophoresis tank running for a long time, there may be abnormal adhesion of the circulation pump and circulation pipeline, which will cause the circulation of the entire pipeline to be poor, regular cleaning and replacement to ensure smooth (semi-annually).

1.5. Avoid failure shutdown. Regular maintenance of circulating pumps and lines (once a month) to prevent abnormal situations and develop emergency plans.

Two, temperature control system

In order to ensure the quality of swimming coating, the temperature of the bath paint is required to be controlled within the range of 28.2 ℃, and the bath is cooled under the normal production state. In the process of electrophoretic coating, there are mainly heat generation in these aspects

(a) Heat generated by electric currents during electrophoresis production

(b) Heat generated by circulating pump agitation

(c) Heat brought in by the coated workpiece

(d) The influence of ambient temperature

Generally, the temperature of the tank is in a rising state, and the control temperature needs to be cooled, but it is usually necessary to heat the tank when the outside temperature is very low in winter. The working temperature of the cathode electrophoresis coating tank is usually (28 ~ 32) ℃, and the temperature of the tank is controlled by cold water of (7 ~ 10) ℃ for cooling and warm water of (40 ~ 50) ℃ for heating. Some enterprises with low paint film requirements use groundwater for temperature control - warm in winter and cool in summer, which can also play a good role.

Maintenance of temperature control system:

(a) Regular maintenance. Regularly check the parameter Settings of the temperature control system and whether the heat exchange pipeline has normal leakage (once a week).

(b) Periodically compare the accuracy of the temperature sensing probe (once a month). Regularly use a thermometer to detect the temperature of the bath and the temperature of the water used in the temperature control system, and compare it with the temperature displayed on the dial of the temperature control system. If there is any abnormality, timely repair or replacement.

Third, anode system

In the process of cathodic electrophoresis, organic acids are continuously produced in the anode region. If they are not removed in time, they will enter the tank and decrease the PH value, affecting the stability of the PH value of the process parameters, affecting the permeability and film performance, and increasing the resolubility. The free acid in the tank is generally removed by anodic diaphragm system.

Maintenance of the anode system:

(a) The anodic solution can be changed regularly according to the color of the anodic solution, conductance and bacterial growth as required.

(b) The conductivity probe in the anode bath fluid should be cleaned regularly, and the anodic fluid conductivity should be measured in a laboratory to calibrate the measuring instrument of the anode system, which can be replaced if necessary.

(c) In the case of empting the electrophoretic solution, under the guidance of a professional, clean the tank on the membrane with deionized water to prevent the pigment residue from drying on the membrane. The same must be done when removing the anode cover. Because the membrane dry bonding will affect the quality of the membrane, the membrane must be kept in a wet environment, and it is more appropriate to remove the membrane in deionized water and store it in deionized water.

(d). It is necessary to periodically check whether the anode circulation system, parameter Settings, and automatic water refill device operate normally.

Four, ultrafiltration system

4.1 The ultrafiltration system is one of the main equipment in the electrophoretic coating process, and its main functions are as follows:

(a) The recovery of electrophoretic paint, in the use of ultrafiltration system, because the ultrafiltration through the cleaning solution can be fully washed to remove the electrophoretic paint adhering to the coated material, recycling, recovery efficiency can be up to more than 95%, saving electrophoretic paint, reduce the amount of sewage treatment and cost

(b) The control of the electrophoresis tank, the conductivity and impurity ion content of the bath liquid in the electrophoresis tank (the dust particles in the bath (the impurities brought by the outside world and the workpiece), condensed particles (the impurities brought by the pretreatment and the by-product of the reaction of the paint liquid) and other mechanical pollutants are cleaned by the filter) can be effectively controlled by the discharge of the ultrafiltration liquid to ensure the quality of the electrophoresis coating film.

4.2 Maintenance of ultrafiltration system:

(a) The filter bag or ultrafiltration membrane tube in the ultrafiltration system needs to be replaced regularly to ensure filtration accuracy and filtration efficiency, and to provide sufficient UF liquid for subsequent flushing. Usually when the UF liquid water flow rate drops below 70% of the normal state, it must be replaced when the water yield cannot be improved by cleaning.

(b) For small independent ultrafiltration, the ultrafiltration machine should be cleaned after each use, and the filter element of the ultrafiltration machine should be soaked in pure water to avoid damage to the filter element; For the continuous work of the online ultrafiltration machine, it is necessary to regularly clean the membrane tube, including forward washing and backwashing, and ensure the liquid output.

(c) Regularly check the pumps and pipes of the ultrafiltration system to prevent abnormal conditions.

(d) Maintenance during shutdown: Usually in the case of a shutdown time of no more than 72 hours, the reverse osmosis system should be washed once a day with pure water and stopped after 30 minutes of operation to prevent water loss or growth of microorganisms; The system must be stored with chemical agents if it is shut down for more than 72 hours.

Five, slot body

The tank body usually includes a primary tank and a secondary tank, and the primary tank is the main storage and working area of the electrophoresis working fluid. The secondary tank is usually arranged at the end of the outlet tank, which can recover the residual paint brought out by the workpiece. It can also contain the foam and dust floating on the surface of the electrophoresis tank during the circulation of the tank liquid, and has the function of eliminating the foam, but the level difference between the main and secondary tanks must be ensured.

Tank maintenance:

(a). Regularly check the aging damage of the tank, and formulate preventive measures to avoid the leakage of paint due to the damage of the tank.

(b). Regular slot cleaning. The disadvantage of cathodic electrophoretic paint is that it is easy to produce precipitation, and the large particles brought by the workpiece will also be deposited at the bottom of the tank, so it is necessary to regularly clean the tank to remove the sediment (at least once a year).