Air filtration on the automotive coating production line

11/08/2020

    If 5mm dust is mixed into the paint layer, the human eye can see the defects caused by the dust. In order to ensure the quality of the paint on the surface of the car, a large number of air filters are used in the production line of the paint shop of the automobile factory to remove the dust in the air from the painting and baking production line.

    The main filter of the spray paint line is arranged above the damping layer or in the air handling unit. The efficiency specification of the main filter is F5~F7, and the main filter is generally an ordinary bag filter. It is the main filter of this section that determines the cleanliness level of the painting environment, not the layer of damping material near the painting tunnel. If the outdoor air contains a lot of dust, there must be a pre-filter before the main filter. In recent years, the new coating workshops of automobile factories are imported production lines or imitated imported production lines, so most of the bag filters are 592×592mm (nominal size 24”×24”) of general specifications.

    The painting line is generally a very long tunnel. The car body travels along the tunnel and undergoes various pretreatment and painting processes. The top of the entire tunnel is covered by a thick layer of non-woven fabric, and the fresh air enters the tunnel evenly through the non-woven fabric. The function of the non-woven fabric on the top of the tunnel is to dampen the current flow. This layer of non-woven fabric has some filtering effect, and it is provided by the manufacturer of the filter material, so people are used to classifying it as an air filter. If you use the method of evaluating filter efficiency to test, the efficiency specification of this layer of damping material is roughly equivalent to F5. In fact, the filter efficiency is not important here, the important thing is that the material itself should be uniform and not shed. You can look at the surface of the material against the light, and shake the material again. Those materials that have nourished or shed hair cannot be used. This kind of non-woven fabric takes up a lot of space, so be careful when transporting, storing, cutting, and installing, and don't let dust contaminate the material.

    In the baking production line of the paint shop, the incoming air must be preheated to about 200°C. Because the heating device may generate dust, the air filter must be placed at the end of the hot air, which requires the filter to withstand 200~ High temperature of 250°C. The efficiency specifications of the filters here are generally F7~F8. All the filters have a partition structure. The glass fiber filter paper with a pleat pitch of about 8mm is separated by corrugated aluminum foil. Due to high-temperature resistance, the problem of adhesion and sealing between the filter paper and the metal frame of the filter is the key, the sealing structure must be reliable, and the cost of the sealing material must not be too high. The gaskets on the filter are mostly flexible glass fiber mats with a thickness of about 5mm. The outer dimension of the filter with the partition in the baking production line is 610mm*610mm*292mm. The pre-filter of the baking production line is located at the inlet of the blower unit, so there is no temperature resistance requirement. For pre-filters, common bag filters with lower efficiency are mostly used. In order to facilitate the management, the pre-filters of the baking line, and the pre-filters of the painting line are often of the same specification.

    Silicone is a very good material. It can be used as a lubricant, adhesive, sealing material, and even as a breast augmentation filler. Silicone is used everywhere in cars. However, the paint shop of the automobile factory is particularly taboo against silicone, because a little silicone on the metal surface will cause the paint layer to bubble. Automobile factories expressly banned any silicone, so filter suppliers should carefully check the various materials used in the filter manufacturing process, especially adhesives, to ensure that they do not contain silicone.

    In a medium-scale paint shop, the annual consumption of the above-mentioned air filters (paint line damping layer material, paint line bag filter, and pre-filter, baking line with partition filter and pre-filter) is 200 Between ~4 million yuan, if you add the filters used in other workshops and office areas, the annual consumption of air filters in an automobile factory can match the consumption of several nuclear power plants. Automobile manufacturers are the coveted meat of all air filter suppliers.