Wisdom For Polyethylene
Sealing method of bag making machine
Heat sealing methods
The polyethylene film is melted and welded by heat, and there are two main types of heat-sealing methods: the heat plate method and the impulse method.
Heat plate method
This method uses a nichrome wire embedded in a brass or copper heating plate to conduct heat to the heating plate, which is then pressed and adhered to the polyethylene tube (under the control of a thermostat).
Impulse method
This metho is to directly heat and weld the polyethylene tube for sealing with a nichrome wire.
Each method has its advantages and disadvantages, but in the case of the heat plate method it is difficult to control the temperature quickly.
In other words, when the temperature of the heat plate drop, the thermostat detects this and switches on to generate heat, but the temperature does not immediately rise to the specified temperature, and a time lag occurs during this period.
The heat plate method also has the problem that the sealing "ends" of the polyethylene tube tend to be pushed by the heat plate and become thinner due to the pressure applied. It is difficult to increase the sealing strength of the seal. However, the advantage of the heat plate method is that the heat source is stored in the brass seal bar, so sealing is completed only by the vertical movement of the hot plate, which can increase production speed.
Therefore, if only seal strength is the only consideration, impulse seals have an advantage, but this results in a higher cost due to the inability to increase production speed cannot be increased.