With the increasing quality requirements of electrophoresis coating film, when customers' existing coating lines cannot meet the quality requirements, the existing electrophoresis products need to be upgraded. At this time, new products need to be used for mixing tank. How long can the mixing tank meet customers' current quality requirements is a matter of great concern, which is expressed by the update cycle in the industry.
Update cycle concept:
In the production process of electrophoretic coating, with the increasing area of the coated object, the electrophoretic coating is also constantly consumed, and the solid content of the tank liquid will gradually decrease. New paint should be added in time to ensure that the solid content of the tank liquid is controlled within the process range to ensure the quality of the coating film. A Turn Over (T.O.) is called when the cumulative amount of electrophoretic paint consumed (or added) reaches the amount of paint used in the initial tank.
Take a component product as an example:
A cathodic electrophoresis tank has a liquid capacity of 40T and a solid content of 16%. 150 parts and components are produced every day. The coating area of each part is 20m2. I worked 25 days a month, and the material utilization rate of electrophoretic coating was 95%. The average solid content of the electrophoretic coating was 39%, and the specific gravity of the coating film was 1.16g/cm3.
Calculation: the amount of electrophoretic paint required by the original distribution tank M0, the monthly consumption of electrophoretic paint M1 under the above production conditions, T.O=M0/M1= (16.41/7.04) =2.3 months.
The actual replacement rate (i.e., replacement rate) of tank liquid in production is calculated as follows:
1 T.O: 63-68%;
2 T.O. : 83-88%;
3 T.O. : 92-97%;
notes for mixing tank
1. Before mixing tank, it is necessary to carry out laboratory or on-site simulation and on-site mixing tank verification, and do on-site equipment review and mixing tank risk assessment before changing the type;
2. During the mixing slot switch, on-site mixing slot plan and promotion plan shall be formulated to ensure the smooth progress of mixing slot;
3. Record the mixing process. If there is any abnormality, give feedback immediately and solve the problem.
4. When mixing tank, it is recommended to reduce the solid content of liquid in the field tank as far as possible without affecting the performance, and then add new paint at one time to reduce the update period of mixing tank, so as to ensure high quality coating film of electrophoresis.
According to a large number of verification test results show that when the mixing tank cycle is above 3 T.O, the film quality can meet the customer's on-site quality requirement
Electrophoretic coating is suitable for mass production, and it is recommended that the update period of mixing tank is 2-3 months, which is conducive to the stability of tank liquid and coating film quality. If the update period exceeds 6 months, it is not conducive to the stability of the tank liquid, and the tank liquid will age, resulting in different coating defects, and eventually lead to a decrease in the quality of the coating film.