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How to deal with the plastic absorption of PP sheet
Sheet Blister
(1) Heating too fast. The following methods can be adopted to exclude:
Lower the heater temperature properly.
Slow down the heating speed properly.
Properly increase the distance between the sheet and the heater to make the heater far away from the sheet. (2) Uneven heating. The following methods can be adopted to exclude:
The distribution of hot air is adjusted by baffles, air hoods or screens, so that all parts of the sheet are evenly heated. Check whether the heater and screen are damaged, and repair the damaged parts.
(3) The sheet is wet. The following methods can be adopted to exclude:
Carry out pre drying treatment. For example, polycarbonate sheet with thickness of 0 (5mm) shall be dried for 1-2h at 125-130 ~ C, and sheet with thickness of 3mm shall be dried for 6-7h; sheet with thickness of 3mm shall be dried for 1-2h at 80-90'e, and hot forming shall be carried out immediately after drying. Preheat.
Change the heating mode to two-sided heating. Especially when the sheet thickness is more than 2nan, it must be heated on both sides.
Do not untie the moisture-proof packaging of the sheet. It shall be unpacked and formed immediately before hot forming. (4) There are bubbles in the sheet. The production process of sheet should be adjusted to eliminate bubbles. (5) Improper sheet type or formulation. Appropriate sheet material and reasonable adjustment formula sheet tear should be selected
(1) The mold design is poor, and the arc radius at the corner is too small. The radius of the transition arc should be increased. (2) The heating temperature of the sheet is too high or too low. When the temperature is too high, the heating time shall be appropriately reduced, the heating temperature shall be reduced, the heating shall be evenly and slowly, and the compressed air micro cooling sheet shall be used; when the temperature is too low, the heating time shall be appropriately extended, the heating temperature shall be increased, the sheet shall be preheated, and the sheet shall be uniformly heated for burning
(1) The heating temperature is too high. The heating time should be shortened properly, the temperature of the heater should be reduced, the distance between the heater and the sheet should be increased, or the sheet should be isolated by the shelter, so that the sheet can be heated slowly.
(2) Improper heating. When forming thick sheet, if single side heating is used, the temperature difference between the two sides is large. When the back side reaches the forming temperature, the front side has been overheated and burnt. Therefore, for the sheet with a thickness of more than 2 mm, it must be heated on both sides