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Undercutting phenomenon of bag making machine

Update time : 2020-12-08

Source : Zhejiang Deguang Machinery Co.,Ltd

Views : 217

Undercutting phenomenon of bag making machine
The undercut phenomenon is one of the common failures of the bag making machine in the bag making process. The reasons for it are mainly in four aspects: heat sealing temperature, heat sealing pressure, heat sealing time, hot knife and silica gel.
bag making machine undercutting
Reasons for undercutting of bag making machine:

1. The heat-sealing temperature is too high: in the bag making process, the heat-sealing temperature is the main reason that affects the sealing fastness. The resin is heated to a certain temperature and begins to dissolve. This point is called the melting point. When the temperature exceeds the melting point of the resin, the resin will produce a paste with a certain viscosity. The temperature setting is generally between the melting point of the resin and the degree of decomposition. Therefore, if the temperature is too low and below the melting point, the material cannot be heat sealed without viscosity. The temperature just exceeds the melting point, the material can be heat sealed but the fastness is not enough. When the temperature reaches the decomposition temperature of the material, the material can be heat-sealed but the material undergoes physical changes, and the edge of the sealing knife is prone to undercutting.
 
2. Heat sealing pressure is too large: heat sealing requires a certain pressure. The normal heat sealing pressure should make the surface of the melted film closely bond together, but also make the melted resin with a certain viscosity can withstand and not collapse. thin. Generally, the standard heat sealing pressure is 2-3kg/㎡. Too much pressure will cause the material to become thinner and cause undercutting. However, when using a wide ironing knife, the pressure should be increased appropriately to ensure the heat sealing fastness.

3. Heat-sealing time: It refers to the time that the heat-sealing hot knife stays on the film, which is reflected in the machine speed and the gap between the hot knife seat beam and the support during the production process. The heat is transferred from the hot knife to the heat-resistant cloth, and then to the heat sealing layer through the printing film, and there is a temperature gradient across the heat sealing section. The thicker the film, the lower the temperature, and the greater the temperature difference between the inside and outside of the film. The heat sealing time should be longer during heat sealing, but shorter. In addition, the single-side pressing bag making machine has a more serious temperature difference between inside and outside. Because of the temperature difference between the hot knife and the heat-sealing layer, the setting temperature of the hot knife is generally higher than the actual temperature required.
 
4. The reason for the hot knife and silica gel: the edge of the hot knife is sharp and not chamfered, the surface of the hot knife is uneven or the heat-resistant cloth is not attached. Too hard silica gel will cause undercutting of the seal. The composite peel strength is poor, and the reinforcing effect of the printing film on the heat-sealing film is reduced, which causes the heat-sealing layer to be stressed and undercut.

Zhejiang Deguang Machinery sells professional bag making machines. Our products are sold all over the world. If you want to know more about the root cutting phenomenon of the bag making machine, please contact us.

Tag: bag making machine undercutting, undercutting of bag making machine reasons