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  3. Ultrasonic sealing
Ultrasonics activates the plastic molecules – friction heat is generated
Ultrasonics activates the plastic molecules – friction heat is generated

Ultrasonic sealing

With ultrasonic sealing, the heat required for melting is only generated inside the thermoplastic sealing layer. For localized conversion of vibrations to friction heat, the anvil or sonotrode profiles are mostly linear and include radii or small plateaus. These profiles ensure focusing of the energy input and therefore short sealing times between 100 and 200 milliseconds. With ultrasonic sealing heat is generated at the inside of the film, not by heat input from the outside as is the case with heat sealing, for example. The tools (sonotrode and anvil) that come into direct contact with the packaging material, remain cold during the entire weld process. The support layer remains almost cold and upon termination of energy input, the heat dissipates faster to the outside due to the temperature difference between the support layer and the sealing layer so that the hot-tack resistance is significantly higher.

Basics Ultrasonic sealing

Ultrasonic sealing is particularly well suited for:

  • Thermoplastic films (pouches and bags) Tubes, trays, and cups
  • Tubes, trays, and cups
  • Cardboard packaging with thermoplastic coating
  • Valves and vents on films / filter materials
  • Screw caps on coated cardboard packaging / films

Generation of heat at the inside of the seal during ultrasonic sealing

Generation of heat during ultrasonic sealing

Joint design

Joint design – focusing by means of contouring of the anvil structure
Focusing by means of contouring of the anvil structure

To initialize the melt formation, it is required for the introduced vibration energy to be focused. With film and other flexible packaging materials, this is achieved through appropriate tool design. More about energy focusing

Joint design

Ultrasonic sealing: Longitudinal seal – Pillow bags – VFFS

Longitudinal sealing ensures protection of the product through reduced drop heights and saves packaging material due to minimum film overlap.

Ultrasonic sealing: Pillow bag with Euro hole punch

Longitudinal sealing and cutting of Euro hole punches by means of ultrasonics.

Ultrasonic sealing: Cross sealing for pillow bags VFFS

Hermetic seals, even with contamination in the sealing area. It is possible to produce completely air-free pouches with liquids.

Ultrasonic sealing: Top seal for stand-up pouch HFS/HFFS

The ultrasonic sealing technology guarantees absolutely tight seals both for hot-fill and for aseptic or retort pouches.

Ultrasonic sealing: Top seal for sachet or pouch HFFS

The vibration of the ultrasonic tools allows for obtaining reliable seal quality despite a dusty filling environment.

Ultrasonic sealing: Longitudinal and cross sealing with Flow Wrapper HFFS

Reduction of rejects counts and product protection thanks to application of cold sealing tools. No problematic cold sealing adhesives required.

Download Ultrasonic sealing

FUNDAMENTALS OF PACKAGING
FUNDAMENTALS OF PACKAGING
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Ultrasonic seminars

Basic knowledge, ideal for packaging companies, machine builders in the field of packaging. The principle of energy focusing through seal shapes and the anvil profile is discussed in detail.
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