How to solve the problem of stripes appearing on the surface when producing ABS composite boards?

How to solve the problem of stripes appearing on the surface when producing ABS composite boards?

There is too much leftover material between the rollers of the calender. The traction speed should be appropriately increased. Generally, the traction speed should be 5% to 10% greater than the speed of the lower roller of the calender. If the traction speed is too slow, it is easy to cause material accumulation, resulting in "zebra stripes" on the surface of the sheet, and the sheet is prone to deformation. If the traction speed is too fast, the longitudinal molecular orientation of the sheet is too large, leading to a decrease in impact strength and a larger shrinkage rate during thermal forming. 
If the temperature of the calendering machine's roller body is too high, it should be appropriately reduced. Generally, the distribution of roller temperature follows a certain pattern and varies with the thickness of the sheet. When the sheet thickness is ≥ 4.5mm, the upper roller is 100~105℃, the middle roller is 85~90℃, and the lower roller is 90~95℃; when the sheet thickness is < 4.5mm, the upper roller is 95~100℃, the middle roller is 85~90℃, and the lower roller is 75~80℃. If the temperature of the calendering roller is too high, the sheet is prone to wrap around the roller. For some resin grades, it is very easy for some adherents to remain on the roller surface, causing pits on the sheet surface; conversely, if the roller temperature is too low, the sheet is not easy to be polished, and the surface finish is poor. 
③ The temperature control at the die head is improper and should be adjusted appropriately. The temperature at the center of the die head for feeding should be slightly lower or the same as that at the connector. For a T-shaped die head, the temperature of each section in the transverse direction should gradually increase from the center to both ends, with an increase of about 5℃. It is particularly important to note that the temperature distribution at the die head must be symmetrical with the center of the die head as the axis of symmetry; otherwise, the sheet is prone to warping. 
④ Unstable discharging and fluctuating extrusion. The amount of recycled material or color masterbatch should be appropriately reduced, and the filter screen should be replaced. Generally, the amount of recycled material should not exceed 40% of the total resin, and the amount of color masterbatch should not exceed 5% of the total resin. Excessive amounts can easily cause extrusion fluctuations. 
⑤ Improper adjustment between the die lips. The distance between the die lips should be appropriately adjusted, and the roundness of the calender rolls should be checked to see if it exceeds the tolerance.
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