How Does Impulse Sealing Work?
Let’s take a closer look at the impulse sealing system used in our wide-web perforated bag-on-roll machine.
Impulse sealing is a heat-sealing technology in which electrical energy is applied only during the sealing cycle. Unlike constant heat sealing systems, the heating element remains at room temperature until a sealing command is given. It heats up rapidly for a precisely controlled period, creates the seal and then cools immediately while the sealing jaws remain closed.
This technology is widely used in:
* Heavy-duty bag making machines
* Perforated bag making machines
* Medical packaging
* Industrial packaging
* Oversized bag manufacturing
* Flexible packaging converting
Because of its precision, energy efficiency and excellent seal strength, impulse sealing has become one of the most reliable sealing methods in the flexible packaging industry.
So How Does Impulse Sealing Work?
The operating principle of impulse sealing is simple yet highly effective.
1. The plastic film is positioned between two sealing jaws.
2. The jaws close and apply uniform pressure.
3. An electric current passes through a resistance wire (typically Nichrome).
4. The resistance wire heats up almost instantly.
5. The film reaches its melting temperature and fuses together.
6. The electrical current is switched off.
7. The jaws remain closed during the cooling phase.
8. After cooling, the jaws open, leaving a strong and durable seal.
Since heat is generated only when needed, the process is highly controlled and repeatable.
Advantages of Impulse Sealing
1. Superior Seal Strength
Impulse sealing provides highly controlled heat distribution, allowing the polymer layers to fuse uniformly.
Benefits include:
* Higher tensile strength
* Excellent seal integrity
* Improved leak resistance
* Longer package life
For industrial packaging applications, seal strength is often the most critical quality factor.
2. Outstanding Energy Efficiency
Because the heating element is energized only during the sealing cycle, energy consumption is significantly reduced.
This results in:
* Lower electricity costs
* Reduced machine heat generation
* Improved overall efficiency
3. Excellent Performance with Thick Films
Impulse sealing performs exceptionally well on thick polyethylene materials, including:
* LDPE
* HDPE
* LLDPE
* MDPE
* Co-extruded films
* Heavy-duty polyethylene films
It is capable of producing strong, consistent seals on film structures reaching 500 microns and beyond, depending on machine design and application.
4. Wide and Durable Seal Profiles
Heavy-duty bags often require wide sealing areas to withstand high loads.
Impulse sealing systems can produce seal widths such as:
* 4 mm – 20 mm or wider
A wider seal generally improves mechanical strength and package reliability.
5. Excellent Seal Appearance
A properly engineered impulse sealing system produces seals that are:
* Smooth
* Uniform
* Symmetrical
* Visually attractive
