Causes and countermeasures of common failures in plastic sheet thermoforming
Release time：
2022-05-13 15:29
Burnt plastic sheet.
(1) The heating temperature is too high. Minimize the heating time, reduce the temperature of the electric heater, and expand the heating.
The distance between the machine and the plastic plate or the choice of shielding protection allows the plastic plate to heat slowly.
(2) The heating method is unreasonable. When the plastic plate is thicker, if single-layer heating is used, the temperature between the two sides.
Relatively large, when the reverse side reaches the forming temperature, the front side has been overheated and burnt. Therefore, for plastic plates with a thickness of more than 2mm, double-sided heating must be used.
The plastic sheet collapsed.
(1) The plastic plate is too hot. The following methods can be used:
① Moderately reduce the heating time.
② Moderately lower the heating temperature.
(2) The fluidity of the raw material solution is too high. The fluidity of the solution should be as low as possible.
The originality of the plastic board increases the draw ratio of the plastic board.
(3) The total area of hot forming is large. Use stainless steel screens and other shields to make heating symmetrical, also available for plastic panels.
The system is heated in zones, so that the middle area does not overheat and collapse.
(4) Due to uneven heating or inconsistency of commonly used raw materials, the melting and collapse of each plastic sheet are different.
The following cleaning methods are available:
① Set up air conditioning blades at various positions of the electric heater to make the heating air evenly distributed.
②The dosage and quality of recycled particles in the plastic plate should be controlled.
③ The mixing of different raw materials should be prevented.
Bright streaks on the surface
(1) The heating temperature of the plastic plate is too high. Reduce heating temperature and heating time as much as possible, avoid plastic plates, and heat electric heaters slowly.
(2) Part of the plastic plate is overheated, and a cover net can be selected to cover the overtemperature position.
Cold material mark pattern on the surface.
(1) The temperature of the pressure-assist plunger pump is too low. Raise as much as possible. Wooden pressure-assist plunger pumps or cotton velvet and fleece-encapsulated plunger pumps can also be used for insulation.
(2) The temperature of the mold shell is too low. Try to raise it as much as possible, but not exceed the drying temperature of the scrap.
(3) Uneven cooling of mold shells. A cooling circulating water pipe or a stainless steel water tank should be added, and the water pipe should be checked for blockage.
(4) The heating temperature of the plastic plate is too high. To minimize, the gas should cool the surface of the plastic sheet slightly before molding.
(5) The forming process is unreasonable. Other forming processes should be used.
plastic sheet,Thermoforming,common error
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