DWL tells you the common coating defects in the construction of color coated steel sheet coating
2019年5月24日
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common coating defects
A. Color difference
1. Paint itself has a larger color difference. Staff should immediately change the color coated steel sheet coating species. 2. Improper film thickness control caused coating color difference. DWL suggested that staff should promptly adjust the film thickness to eliminate color difference. 3. Improper control of the PMT causes coating color difference. The furnace temperature should be promptly adjusted. And staff should adjust and control in accordance with the adjustment scope of PMT provided by paint manufacturers as far as possible. 4. Improper control of baking time and air velocity in the furnace can also cause color differences in the color coated steel sheet coating. Staff should promptly adjust the speed of production technology and adjust the into and out flow balance of furnace air.
B. Gelosis or pocking mark
1. Caused by substrate rough or substrate defects. Then should replace the substrate. 2. Before coating, the paint is contaminated and influence the color coated steel sheet coating surface. Then should change the paint or filter coating. 3. During coating, the indoor dirty air in coating machine pollutes the coating surface. Then should purify the indoor air in coating machine timely. 4. The too heavy acid gas causes the paint hardening. Then should adjust the furnace temperature temperature in time. 5. The air in furnace is dirty, the coating surface is contaminated and cause the pocking mark. Then should stop the machine and clean the furnace air. 6. Cooling water is too dirty and contaminate the coating surface in the cooling process. Then should timely change clean cooling water.
C. Point-like film loss occurs at high speed coating
1. Improper control of the PMT causes film loss of coating. Then should adjust the temperature in time. 2. Roller ratio does not match. Then should adjust the roller speed ratio. 3. There are defects in the coating roller. Then should replace the coating roller in good condition timely. 4. Improper coating viscosity causes film loss of coating. Then should adjust the viscosity of the paint.
D. The coating thickness on both edges of strip is different
The reason is that the roll gap between the coating roll and the sticky roller is not uniform at both ends. Then should stop the machine and adjust the balance of roll gap at both ends.
E. There find horizontal stripes in the wet coating surface
1. Caused by horizontal stripes in the galvanized layer of substrate. 2. Caused by the unmatched speed ratio. Then should adjust the roller speed ratio.
