New Tech Comes to Heat Seal Bars

This packaging machinery OEM is pioneering the use of a brand new method of making heat seal bars that is adapted from printed circuit board manufacturing.

SN Maschinenbau is a German manufacturer of horizontal pouch packaging machines. In the past few years SN has led the way in the use of a new heat-seal bar technology from Germany’s watttron called cera2seal. Unlike the technology used for many years, where the same temperature is delivered across the entire length of the seal bar, with cera2seal the temperature can be controlled in a targeted manner.

Not all pouch-sealing operations require this dynamically regulated temperature control. But in a standup pouch or a pouch with a zipper or spout, the material is thicker in some areas due to folds that are required. Thus, in some areas across the length of the seal being made, the tooling needs to close on four layers of flexible film while in other areas it closes on just two layers. With watttron’s tooling, it’s possible to deliver 200º to the four-layer areas and just 150º to the two-layer spots. And that, of course, brings cost and sustainability benefits.

“When we started to integrate the watttron sealing tools into our machinery, we noticed that we had a significantly lower heat input into the machine body,” says Gunnar Flosbach, Head of Development and Design at SN. “We’ve seen lower energy consumption, which of course is a great advantage in view of today’s emphasis on environmental concerns.”Integrated control electronics inside the watttron sealing bars deliver varying temperatures to electrical circuits printed on the seal bar’s ceramic/aluminum oxide surface.Integrated control electronics inside the watttron sealing bars deliver varying temperatures to electrical circuits printed on the seal bar’s ceramic/aluminum oxide surface.

Another reason it’s desirable to have greater control over heat sealing temperatures has to do with recent and increasingly rapid developments in monomaterial packaging films. The idea behind such films, of course, is that if you’re not combining things like aluminum foil, polyester, or nylon, for example, in a largely polyethylene composition, the resulting material fits far more readily into the existing and well-established PE recycle stream. But these new mono-materials are more easily damaged or tend to stretch too much if the heat being applied to them is not optimally controlled. The watttron tooling delivers this optimal heat control.

A third benefit to the cera2seal technology is that due to the low thermal mass of the system—i.e., the tooling is much lighter—heat up and cool down are very quick. This allows easy access to the machinery by operators and minimizes potential for danger. Included is an LED display that signals the operator when the sealing element is safe to touch.

Elsewhere in the world of pouch sealing technology, the FPA honored Amcor with a Gold Award in Technical Innovation for its Dual Chamber Pouch, a specialty multi-layer pouch consisting of a peelable medical device chamber and a non-peelable desiccant chamber.

So much for the “what” of cera2seal, which, it’s important to point out, can be retrofitted onto existing form/fill/seal machines. What about the “how?” According to watttron CEO Marcus Stein, the manufacturing process behind cera2seal is based on ceramic thick film technology commonly used in the making of printed circuit boards (PCBs) in the computer industry. So it’s fundamentally a matter of printing electrical circuits onto a ceramic/aluminum oxide substrate. A key difference is that the PCBs found in the computer industry are not designed for a high-temperature environment. So watttron’s technology bears more similarity to the PCBs found in the automotive or aerospace industries, where electrical circuits are printed onto ceramic/aluminum substrates in a way that permits them to function in high-heat environments.

What’s actually printed along the length of a watttron seal bar is a series of individual zones each measuring 5 mm sq (about 12 sq in.). Each zone is independently controlled by integrated control electronics. A central information and intelligence unit called the watttrix server functions like a small PC and communicates to each zone what temperature it should deliver and receives back the real temperature of each zone.

SN currently has horizontal form/fill/seal systems running commercially at customer plants where side seals are made via watttron cera2seal technology. In development are machines that will also use cera2seal tools to seal pour spout fitments to flexible film pouches.

One note of interest is that before watttron delivered its unique flexible film sealing capabilities, it was working on a similar version of the technology that was designed for the tooling used on thermoforming machinery. In fact, at PACK EXPO Las Vegas 2019, CEO Stein delivered a presentation on this cera2heat topic as part of the Innovation Stage series. But making thermoforming tooling a commercial reality proved a little more complicated than heat seal tooling. Stein does indicate, however, that pilot applications in thermoforming are in place and that he expects that 2021 will see an announcement on progress made in the thermoforming space.

Finally, watttron readily acknowledges that its heat seal tooling comes with an upcharge. Stein describes it as higher than traditional conductive sealing but lower than ultrasonic sealing. But if it delivers such things as more uptime, flexibility, manufacturing consistency, and improved quality control, Stein believes that OEMs and Consumer Packaged Goods companies alike will be only too happy to make the investment.

Go to pwgo.to/6028 for a video animation showing the wattron tooling in action.

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