Ultrasonic Technology Vs. Heat Sealing

Close-up view of vertical ultrasonic sealing system integrated on a VFFS. The anvil compresses two edges of clear packaging material against the horn to weld a continuous vertical seam. Image courtesy of Emerson.

Four Reasons to Consider an Ultrasonic Retrofit

By Andres Abreu, Packaging Business Development Manager, Assembly and Welding at Emerson

As consumer packaged goods (CPG) makers confront questions about sustainability, recyclability and profitability, they should consider the latest energy- and material-saving advantages available for vertical form-fill-seal (VFFS) equipment. One such improvement involves retrofitting VFFS equipment to use flexible, energy- and material-saving ultrasonic sealing technology in place of heat-sealing bars, for package sealing operations.

There are several reasons to consider this change:

1. Energy savings. Because conduction heat-sealing systems must be continually powered and maintained at a precise operating temperature, they consume high amounts of energy. Consider two packaging lines of comparable capacity, producing 100 welds per minute, 16 hours per day. A conduction heat-sealing process might require four 500-watt cartridge heaters (2,000 watts per hour or 32,000 watts per day) to continuously maintain seal-bar temperatures. An ultrasonic welder of similar capacity would require a power supply rated at 1,500 watts peak power but would consume power only in short bursts (~200 milliseconds per weld x 100 welds per minute = 20 seconds per minute of power, or about 24,000 watts per day). Using these examples, the ultrasonic heat-sealing process requires 25% less energy at maximum output.
2. 

   Close-up view of horizontal ultrasonic sealing system integrated on a VFFS. Actuators drive the attached ultrasonic stack towards the anvil, compressing the clear material and creating a narrow, but strong seal for the bottom and top of the formed bag. Image courtesy of Emerson.

   Material savings. A snack food packager producing small VFFS snack bags (6-inch size) consumes about 1.0 inch of total package length to produce two conventional heat seals (0.500 inch each on top and bottom) per bag. Two comparable ultrasonic welds require just 0.25 inch of total package length (0.125 inch each on top and bottom) resulting in a per-bat material savings of 0.75 inch (0.375 inch x 2) for a package with the same net product volume.

3. Improved seal reliability. Certain products can leave oils, liquids, plant matter or residue on sealing surfaces that can become encapsulated within conventional heat seals, resulting in contamination, leaks or failures. The vibratory motion of ultrasonic welding not only heats the sealing surfaces, but first vibrates or “cuts” through potential contaminants within the sealing area, resulting in a stronger, more reliable seal.
4. Improved sustainability. As CPG makers strive to produce more sustainable single-use packages, they must consider biodegradable package materials like polylactic acid (PLA). But biopolymers like PLA contain less polymer content, so achieving commercial-grade seals is more difficult. To bond such packages, more packagers are leveraging the extensive melt-control capabilities of ultrasonic welds. Compared to heat seals, which control only four factors — temperature pressure, time and shape — ultrasonic welding offers precise, programmable and repeatable control over more than a dozen critical factors in the welding/sealing process. Greater sealing control means greater process flexibility and reliability.

If you are curious about what an ultrasonics retrofit could do for your packaging operations, contact a skilled and experienced ultrasonic welding supplier. They can assess your VFFS equipment, package design, materials, and throughput requirements and offer definitive advice about how an ultrasonics retrofit might work and help predict the material and energy savings. These advantages, together with the potential to utilize newer, biodegradable materials, might also strengthen your sustainability and your competitiveness.

About the Author

Andres Abreu is a packaging business development manager, Assembly and Welding at Emerson. He has over 15 years of experience working primarily for Fortune 500 companies, responsible for business development and generating sustainable retrofits in the industrial sector to increase company valuation and reduce environmental impact. He has a bachelor of science in electronic engineering from the University of Akron.  Learn more at www.emerson.com/branson.