Meaning
Direct heat application techniques provide a more consistent thermal transfer than impulse sealing methods when working with thick gauge barrier films. In the operation of hot bar thermal sealing, two metal jaws are maintained at a constant temperature and pressed together to fuse two layers of plastic. This method is preferred for high-speed production lines because the bars do not need to cool between cycles.
Heat Transfer
Conduction moves energy from the heated metal through the film to the interface. The efficiency of hot bar thermal sealing depends on the dwell time and the pressure applied by the jaws. If the film is too thick, the heat may not reach the center of the seal before the bars open.
Bond Integrity
Strength in the final package is a function of the molecular entanglement that occurs during the heating phase. Overheating during hot bar thermal sealing can cause the polymer to degrade or thin out, resulting in a weak spot. A properly calibrated system ensures that the seal is as strong as the original film.
Cycle Speed
Rapid production requires a seal that forms instantly. Because hot bar thermal sealing uses pre-heated components, it can achieve faster speeds than systems that must ramp their temperature up and down. This efficiency lowers the cost per unit.
