In vacuum packaging machines, "single sealing point" and "external vacuum" refer to the sealing structure and the vacuum extraction method respectively. They belong to different classification dimensions, but are often discussed together. The two are not mutually exclusive and are frequently combined in actual equipment.
1. Single Sealing Point
A single sealing point is the most basic sealing configuration. The machine is equipped with only one independent heating sealing assembly. After vacuum extraction is completed, the heating bar presses directly against the bag opening and completes sealing through heat fusion, leaving only one continuous sealing mark on the bag mouth.
It is suitable for conventional flat packaging bags, such as ordinary composite plastic bags and aluminum foil bags, as well as small-scale packaging operations that do not require extremely high sealing precision. Its limitations include difficulty in handling irregularly shaped bags, relatively weaker seal strength, and support for only one-direction vacuum packaging.
For different bag widths and seal strength requirements, sealing heating bars, pressing strips, insulating backing plates, and mounting bases often need to be custom-made according to the machine model. Hansheng Automation provides machining services for these sealing components based on customer drawings, supporting material selection and dimensional fit to suit different bag materials and sealing processes.
2. External Vacuum Type
External vacuum is a classification based on the vacuum extraction method. The machine does not place the bag inside a sealed vacuum chamber. Instead, an external vacuum nozzle is inserted into the bag opening to extract air directly before sealing, so the vacuum process does not depend on a sealed chamber.
Its main advantage is the ability to handle large items that cannot fit into a vacuum chamber, such as large hardware parts, bedding, and industrial components. It also supports irregular packaging with rollers or protruding structures. Most external vacuum packaging machines on the market still use a single sealing point configuration, while some high-end models use double sealing points for reinforced sealing.
3. Common Combinations
A single sealing point can be used in either internal vacuum or external vacuum machines. External vacuum equipment can also be equipped with a single sealing point or multiple sealing points. Common combinations include:
Small household or commercial vacuum machines are mostly internal vacuum with a single sealing point.
Industrial packaging for large items often uses external vacuum with a single sealing point.
Food and pharmaceutical industries with high sealing requirements tend to use external vacuum machines with double sealing points.
