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It uses only 20-25% of the energy of a heat sealing station. Ultrasonics vibrates contamination out of the sealing area, which allows reducing the headspace. The minimum width for a heat seal is approx. 8mm and with ultrasonic it can be reduced to 2mm.

In answer to our open-ended question regarding trends for V-F-S-S baggers, “the biggest trend we’re seeing is for ultrasonic welding,” responded Triangle’s Ray Kondracki. He was not alone in singling out this underutilized technology as one that’s gaining traction in a market dominated for decades by heat sealing. Five V-F-F-S vendors at Pack Expo demonstrated the technology.
During ultrasonic sealing, high-frequency sound waves (in the range of 20,000 to 40,000 per second) focused on a substrate are converted into frictional heat to create a molecular bond between polymer layers. Essentially, the substrate heats from the inside-out, rather than outside-in as with heat sealing.
Bosch Packaging Technology, which has offered ultrasonic sealing as optional on its baggers for several years, notes the following benefits:


• Ideal for heat-sensitive products
• Reduced sealing time increases machine output
• Narrow sealing width saves packaging material
• Sealing through product—including liquids—reduces product and package waste


CapriSun drink pouches are sealed ultrasonically, notes David Considine, sales manager for packaging at Hermann Ultrasonics, which supplies sealing assemblies used for packaging applications.
Although the cost of ultrasonic sealing is around six times that of a heat-seal assembly, Considine says that ultrasonics use only 20% to 25% of the energy of heat sealers.       

     

More importantly, there is also the potential to use less complex—and less costly—structures and reduce web thickness, Considine notes.
A drawback to the technology is that packaging materials have been long been designed for heat sealing, not ultrasonic. However, says Kondracki, “as the use of ultrasonic sealing becomes more desirable, films will be optimized for this technology. This means that films can become thinner or they can lose sealant layers that will also make them more sustainable.”

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