Mono-materials? Sealable with ultrasonic

With a view to sustainability, Herrmann Ultraschall’s ultrasonic technology guarantees the safe sealing of recyclable materials and flawless packaging aesthetics.

The packaging industry has identified mono-materials, paper and cardboard as the most sustainable packaging materials. Sealing these materials in a safe and aesthetically flawless way, however, poses a significant challenge to conventional joining processes. After making due comparisons, according to Andreas Runck (systems developer in Herrmann Ultraschall), the ultrasonic sealing system makes the process simple and efficient. 

Traditional systems vs ultrasonics

Conventional processes, such as heat-sealing, rapidly reach their limits, since they function with heat applied externally, which can lead to the film shrinking and wrinkling, compromising the airtightness and aesthetic appearance of the package.

As a result, reject rates are high and cause unnecessary waste, both of packages and foods. With ultrasonic, thermal energy is generated only due to the friction between the materials inside the sealing zone. In addition, the energy can be precisely controlled and adapted to every individual material. This guarantees a reproduceable result, also with very narrow processing windows.

A low energy-consumption technology

The process requires energy only during the short sealing time, between 100 and 200 milliseconds, reducing energy consumption in this way by up to 75 percent. During the process, the sealing tools remain cold, making it possible, therefore, to reliably seal also packaging which is paper-based and with a low plastic content. This is true both for the thinnest and thickest layers of paper, such as the cardboard used in beverage packaging.

Material analysis for the best sealing solution

Cartons for beverages, in particular, have a thin layer of aluminium inside, which makes it possible to seal the package by induction. For ecological reasons, however, an ever-higher number of companies are planning to eliminate this layer in packaging: for these applications, it’s therefore necessary to find alternative joining processes, such as sealing with ultrasonic.

The use of ultrasonic facilitates, in this way, the transition to mono-materials or other recyclable packaging materials and opens up the way to a more sustainable packaging approach.
It may be sufficient to adjust the sealing parameters when passing to mono-materials or paper-based packaging materials. It could be necessary, however, to develop a completely new sealing process, especially in the case of using new types of film. Only in this way will it be possible to guarantee a reliable process with hermetic seals and flawless aesthetics. Feasibility testing in ultrasonic laboratories is carried out to assess whether a material or its composition can be sealed with ultrasonic.