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Good vibrations

marzo 2009

Ultrasonic sealing - a sealing method that creates smooth, ultra-strong bonds formed through high-frequency vibration.

GOOD VIBRATIONS: Ultrasonic Sealing Holds Promise for Cheese

What does Michael Phelp’s swimsuit and next-level cheese packaging have in common? The answer is ultrasonic sealing—a sealing method that creates smooth, ultra-strong bonds formed through high-frequency vibration.

Phelp’s famous formfitting bodysuit featured ultrasonically bonded seams, which eliminated drag caused by bulky stitches, and contributed to record-smashing Olympic times.

Technology leaders believe ultrasonic sealing also holds considerable promise for North American food packaging, with the potential to deliver fully repeatable, 100% reject-free cheese packaging despite seal contamination, while streamlining production output to unprecedented levels.

To bring readers up to speed, we spoke with Dave Considine of Herrmann Ultrasonics, Inc., and Bob Williams of Triangle Packaging Machinery, two thought leaders on the forefront of ultrasonic development in North America.

Ultrasonics Sealing 101

Considine, from the North American division of German-based Herrmann Ultrasonics, describes ultrasonic sealing as a fast, repeatable and highly economical method for joining flexible packaging materials. Using high frequency, ultrasonic generates a true molecular bond with high strength and a reliably consistent hermetic seal. The packaging material literally welds together with heat generated by vibrations at a frequency of 20-35 kHz.

Ultrasonic sealing was developed globally in the early 1960’s to weld plastic injection-molded parts. As the technology evolved into the packaging market, applications included beverage carton sealing, tube sealing, zipper crushing, standup pouch sealing, and vertical and horizontal pouch sealing. Used primarily in Europe, the technology’s initial success was driven by its ability to deliver hermetic seals through product contamination.

The high vibration used in the ultrasonic process has an added bonus for products with fines in the seal area like shredded, grated or powdered cheese: the vibration created through the process is able to shake away any food product from the seal area that may enter and possibly compromise a hermetic seal.

Herrmann Ultrasonics—one of Europe’s leading suppliers of ultrasonic sealing equipment— demonstrated the technology recently at Interpack, and is beginning to market the solution in North America.

While the technology is not common here and has not been fully commercialized for cheese, trendwatchers are keeping a close eye on its progress.

What’s the Big Deal?

The ability to create a “super seal” that delivers 100% seal integrity—despite fines, additives and contamination—is the primary benefit ultrasonics has over heat-seal operations. This unique capability addresses one of the top challenges of heat-seal packaging for cheese: leakers caused by defective seals (and the related issues of mold or moisture loss that can occur). How reliable is it, really? In retort applications, the reject rate of ultrasonics is significantly less than 1 per 50,000 seals. While reject rates for cheese packaging in beta testing is confidential, Considine is fully confident the zero-defect promise will stand.

But according to Williams and Considine, seal quality is only one of a bonanza of potential benefits. Ultrasonic-sealed packaging:

Significantly reduces leakers
Requires less energy
Reduces machine height with potentially smaller footprint
Eliminates use consumables such as Teflon® tape, cohesive or other
Seals well through small pleats and wrinkles
May offer opportunities to use thinner gauge or more sustainable packaging films
Uses less packaging material, due to smaller, more precise seal areas

Record-Setting Production Gains, Predictability

While ultrasonic sealing does not make sense for every application, it holds extreme promise for high-volume cheese packaging operations focused on 24-7 uptime and high-speed production. It may be especially attractive to processors looking for the efficiencies of data-driven production and quality processes.

Production gains begin with streamlined setup and changeover. As a cold-seal process, ultrasonics eliminate the time it takes for heat-seal equipment to warm up and dial in—typically 10-15 minutes. Heat-seal changeovers also typically range an average of 45 minutes, a “time-out” eliminated by ultrasonic technology’s PLC controls. Besides being lean, the sealing process is more clean: operators have to clean residue from the seal jaw much less often.

Considine also stressed that his company’s closed-loop sealing station gives processors the ability to receive real-time feedback for each seal made. Quality parameters stored in-generator compare each seal made with preset values: if the inline seal falls outside parameters, a message is immediately set back to the PLC, so the operator can reject the pouch or stop the line. Each seal is validated using predetermined process parameters, delivering unmatched repeatability and a uniform high-quality level.

The technology also increases operator safety, because it eliminates the hazard of hot sealing bars.

Food Applications

Today, the largest ultrasonic sealing application in North American is beverage pouches—at a rate of over 4 billion packages per year. Additional commercial applications include hot-filled or retort liquid applications including sauces, chocolate, meat and cheeses. The technology is also used to weld ends of reclosable zipper to film.

According to Considine, HFFS, VFFS, lap seal and fin seal applications are all suited for ultrasonic sealing. Herrmann currently produces sealing systems and modules for both VFFS and HFFS packaging systems, as well as standup pouches and pre-formed bags. However, both Considine and Williams agree that one of the most valuable and immediate applications is VFFS pouch sealing for shredded or grated cheeses.

Cost Implications

Ultrasonic sealing systems are significantly more expensive than heat-sealing systems. Yet payback can occur in a range of 6-20 months, due to savings generated by energy reductions, productivity gains, waste reduction and reduced packaging material. Williams notes that the total cost of ownership, always a key purchase decision factor, could be dramatically reduced using ultrasonic sealing compared to traditional heat sealing technology. This is particularly true in a multi-shift, high production “24/7” 365 day environment thanks to material and energy savings.

Saving factors include:

Space: Requires much smaller machine height for space efficiency
Energy: Uses just 20%-25% of the total energy needed for heat sealing in compatible systems, for a whopping 75%-80% savings
Throughput: Delivers cycle time and throughput improvements due to instant, on-demand startup and changeovers.
Reworks: Reduces waste and cost caused by packaging rejects (material and product)
Material: Reduces material required for the seal area, resulting in better film yield; offers possibilities for using lighter, thinner, more sustainable materials; and delivers “right-sizing” material savings through smaller primary or secondary packages
Labor: Reduces labor cost/manpower needed to inspect sealing quality; empty and deal with rejected products; and clean residue from jaws
Consumables: Eliminates the need for consumables such as Teflon® tape
Freight: Delivers freight/transport savings due to packaging and machine weight reduction

Equipment Requirements

According to Williams, machinery designed for ultrasonic sealing is not in Triangle’s current product portfolio, but the company is currently working with Hermann Ultrasonics on integrating ultrasonic technology in the cross jaws and back seal areas of a VFFS machine.

He says the cold-seal process presents a new set of design challenges that will require machine design enhancements and modifications such as a more robust jaw carriage for enhanced stability.

Williams is confident that as a result of the work being done with Hermann Ultrasonics, Triangle will bring equipment forward that is proven, sound and practical: “We have over 85 years’ of packaging machine history…that has provided us with tremendous application experience that goes far beyond just making a machine. We understand that at the end of the day, the objective is to produce more “sale-able” packages; either through higher output, or more attractive packages and hopefully both. Our machinery really is a means to an end for cheese processors, and we are dedicated to exploring all opportunities that can give our customers a competitive advantage,” he said.

Material Requirements

To date, cheese film and pouch materials have been developed for heat-seal applications, but they haven’t been optimized for the new technology. However, Curwood market and material science specialists are in the process of developing thinner, faster, stronger flexible materials that meet barrier and aesthetic needs, while also being engineered with enhanced characteristics for the ultrasonic process.

Dave Engen, Market Manager for Cheese, believes Curwood’s strength and leadership in technology innovation for the cheese market places the company in a perfect position to deliver Ultrasonic film solutions.

“Materials will require a certain amount of customization for each format and application to deliver the optimum material performance and seal properties,” he said. “More upfront homework will be needed for ultrasonics versus what is traditionally required for heat sealing. For example, how the sonotrode is designed affects the ultrasonic waves and their interaction with the film. Some packages may incorporate heat seals as well as ultrasonic seals, which will require different film properties than a material using only ultrasonic sealing.” Moreover, says Engen, “One material solution that fits all ultrasonic applications is unlikely. The optimization of the sealing module, tooling and packaging materials are key to successful sealing. The proliferation of successful ultrasonic applications will require the involvement of material suppliers further upstream in the process.”

Implementing Ultrasonic Sealing

According to Dave Considine, a typical ultrasonic retrofit project would involve a seven-step process that integrates a team with multiple areas of expertise, tapping vendors such as Herrmann Ultrasonics, Triangle and Curwood:

Cost analysis to ensure increased bottom-line profitability
Verify feasibility to weld desired packaging materials
Sample testing to confirm materials performance
Review machine design for robustness
Integrate ultrasonic sealing modules into the machine
Mechanically install the sealing station (1 day) and electrical PLC integration (1 additional day)
Train operators and maintenance support team

Considine notes that training is crucial for a successful transition from conventional heat sealing to ultrasonics. Processors should expect less training for operators, but more technical education for maintenance staff. Ultrasonic technology is more complex, he states, but has fewer parameters to change on a regular basis.

Paradigm Shift

Both Considine and Williams believe ultrasonics will open up markets and applications to truly change the industry. Yet to succeed, the technology requires cooperation between cheese processors, film, sealing companies and machinery companies on a level like never before.

“For generations, machinery companies have been kept at an arm’s length from material suppliers and only worked together with each other after a customer put us together. But the first time a bagger runs film should not be on your production floor. In order to truly optimize a machine’s technology and film capabilities machinery OEM’s and film manufacturers must work together. That is what is so exciting about this project between Triangle, Hermann and Curwood,” said Williams.

He suggests the cheese industry will need to rethink its current supply model in order to successfully incorporate ultrasonics. A new level of partnering is necessary to shorten the development cycle and hold down transition cost—working together to implement commercially viable packages for the cheese market.

In fact, Hermann Ultrasonics and Triangle Packaging Machinery are currently working together on a prototype VFFS bagger utilizing ultrasonic sealing in North America with packaging films from Curwood and other film suppliers. The team anticipates a commercially robust solution for food packaging for cheese as early as mid-2009.

So if, like Phelps, you’re open to diving into a technology that streamlines performance, stay tuned to the latest vibe.

Learn More

For more information about Ultrasonics, Equipment and Films, please contact:

Jill Hanegraaf at Curwood, Inc.
Office: 920-303-7440
Email: curwood(at)bemis.com

David Considine at Herrmann Ultrasonics
Office: 630-626-1656
Email: dave.considine(at)hermannultrasonics.com

Bob Williams at Triangle Machinery
Office: 773-889-0200
Email: bwilliams(at)trianglepackage.com

Curwood, Inc.
P.O. Box 2968
Oshkosh, WI 54903

920.303.7440
curwood(at)bemis.com