Coloured galvanized sheet may have surface scratches due to transportation and man-made construction. The scratches belong to defective products and will be affected when used. Therefore, we should pay attention to the causes of scratches and prevent
them in time.
1. Substrate scratches
2. When making veneer, pay attention to the scratch on the back of the veneer, which causes color difference, light color on the back, and easy to produce color difference.
3. Scratch of spray pipe (mainly on the front of strip).
4. Entrance section: scratch of guide plate (main back).
5. Scratches in solidification furnace: sagging objects in furnace body (common); front scratches with excessive tension, mainly referring to excessive tension when thick material is changed into thin material.
6. Scratches on exit loopers are common when parking or unloading.
7. Scratches on extruder rolls, usually when the extruder rolls do not rotate.
8. Foreign body scratches in the exit section, foreign body on the exit guide plate, multi-finger back or scissors scratches on the surface of color-coated galvanized sheet.
9.S roll scratches, water-cooled extrusion effect is not good, bring water to S roll, the tension of furnace body and outlet looper is too different, resulting in S roll skidding.
10. Initial temperature of solidification furnace plate is not enough, paint solidification is not good, stabilization roll sticks back paint before water cooling.
2. Determining the specific site of the scratch
1. The first step is to determine the scratch before and after application.
2. Scratch before drying or after drying.
The above-mentioned reasons for scratches on color-coated galvanized sheet are introduced in the hope of giving you help. When using and installing the sheet, we should pay attention to the correct installation method, fix the sheet, and prevent accidental scratches by the equipment.