J&J Snack Foods, the world's largest producer of soft pretzels, has seven production lines making the popular snacks at its plant in Pennsauken, NJ. Last October, the plant installed a vertical form/fill/seal machine from Rovema Packaging Machines (www.rovema.com) to run its latest frozen SuperPretzel(R) bite-size products: Soft Pretzel Bites(R), Pretzelfils(TM) and Softstix(R).

Soft Pretzel Bites are short pieces of soft pretzel, while Pretzelfils and Softstix are small pieces of pretzel with fillings and/or toppings. The products are filled into 9-oz bags at a speed of 55 bags/min by the Model VPK continuous-motion Rovema machine, after which they are hand-packed into cartons and are frozen. "We have other Rovema equipment at other J&J plants, and they have really worked well," says director of engineering Phil Heffelfinger. "They have also given us great service. A large percentage of our workforce is Vietnamese, and one of Rovema's startup and service people speaks Vietnamese. He conducted classroom sessions as well as hands-on training in Vietnamese and English. As a result, this was a very successful startup," he says.

J&J reviewed several reseal options for the bags and decided on a unique bag-resealing system from Sealstrip Corp. (www.sealstrip.com) that uses pressure-sensitive tape instead of the usual zipper closure. In this process, a slot is cut in the film, and the tape is applied over the slot. The consumer presses the adhesive side of the tape against the opposite side of the bag to reseal the bag after it has been opened. The tape is applied to the film entering the machine and travels through the f/f/s operation as an integral part of the film.

J&J had used the Sealstrip system earlier and actually retrofitted a system to an existing packaging machine in the plant with good success. "The tape runs through the machines with no problems, and it holds up very well to freezing," says Heffelfinger. "The Sealtape closures cost a fraction of a typical resealable zipper per package and are very user-friendly." (Details of this operation are given in the sidebar)

The Sealstrip applicator is a standalone unit that is located at the back of the Rovema machine. The roll of film, which was supplied by Advanced Packaging Corp., is normally located on the back of the bag machine, but the film spindle was moved to the back of the Sealstrip applicator for this application. "Rovema sent the spindle to Sealstrip to install it on the applicator, and Sealstrip then sent the entire applicator back to Rovema to mount it to the bag machine," says Heffelfinger.

J&J Snack Foods uses a Rovema Model VPK vf/f/s machine at its plant in Vernon, CA, to run Newman's Own cookies in flat-bottom bags. Read about it at www.packagingdigest.com/ info/vernon

Integrating the film and Sealtape was also a joint effort. "We wanted the customer to be able to reseal the bag from four to eight times, and the film had to travel through and seal on the Rovema machine without causing problems. It also had to stay sealed in the home freezer," says Heffelfinger. "In addition to the sealability of the Sealtape, the slip of the film moving through the machine was critical. Sealstrip and Advanced Packaging would modify their materials and then we would work with Rovema to see how they performed. These ‘trial and error' efforts took about six months before the machine was installed."

The film is pulled through the Sealtape applicator and into the VPK bag machine by a combination of friction-drive belts and a vacuum assist on the front of the machine. A sensor detects the location of the edge of the film as it leaves the roll and moves the entire film carriage horizontally to maintain the proper tracking through the machine. The film passes over a series of rollers and dancer bars at the top of the f/f/s machine, and these, along with an air bladder in the film spindle, maintain the proper back pressure on the film as it is pulled continuously through the machine. The film passes around a forming tube on the front of the unit, and continuous hot air produces the vertical overlap seal. Pretzels drop intermittently from an Ishida overhead weighing system from Heat and Control, Inc. (www.heatandcontrol.com) through the forming tube into the continuously moving formed cylinder of film as it leaves the vertical forming section.

An ink-jet printer from Diagraph, an ITW Co. (www.diagraph.com) applies the date, time and product name to the film as it passes over the forming collar. An encoder continuously measures the speed of the film and automatically adjusts the printing speed to correspond to the film speed.

Next, the film passes through the servo-driven sealing jaws, which move in a D-configuration. The jaws move in against the film and induction-heat a horizontal seal across the film. The jaws move downward with the film for the required time to create the seal, and then move away from the film and reciprocate up to start the next sealing cycle. At the end of each sealing cycle, before the jaws disengage, an air-actuated blade shoots out from the center of the jaws and cuts the bag loose, after which it drops onto the takeaway conveyor.

Although it is not needed for the clear film that J&J is running, the vf/f/s is equipped with a sensor mounted on the film carriage that detects the eye mark on the film. If the plant were running printed film with an such an eye mark or registartion spot, this sensor would initiate the start of each cycle. It compensates for any slight changes in the film length and ensure that the film for each bag would always be in perfect registration. This system basically tells the horizontal sealer and cutoff knife when to energize and tells the code dater when to operate.

The machine is controlled by an Allen-Bradley programmable logic controller and incorporates an A-B PanelView operator panel and three A-B Ultra 3000 servo drives that operate the vertical sealer, the left and right pulling belts and the seal jaws/knife assembly. The Allen-Bradley components are supplied by Rockwell Automation (www.rockwellautomation.com).

The PLC maintains the recipes for all of the products in memory, and the operator can recall them at a touch. The unit automatically sets the operating parameters, including the sealer temperatures and the servo drives that, among other things, set bag length. Additional touches of the screen display the settings currently in use, causes of operating problems and maintenance requirements.

Product for the f/f/s machine is weighed by a 14-head radial-weighing system that is located on a platform above the machine. Product is delivered on a vibrating conveyor that discharges onto the Ishida weigher's dispersion table.

The dispersion table transfers the product to the 14 radial feeder hoppers, which, in turn, move the product by vibration to the pool and weigh hoppers. Each radial feeder adjusts the strength and duration of vibration to ensure an ample supply to the hopper. Once the product is in the hoppers, the weigher's computer selects a combination of buckets (generally three or four) that cumulatively equals the closest weight to the total bag weight without being under that weight. The selected hoppers then open and discharge their contents down the discharge chute to the bagger.

The Ishida features an easy-to-use computer-controlled operator interface that provides a clear display of charge weight as well as various statistical data. Along with an intuitive control, the Ishida also simplifies cleaning and minimizes downtime with its design focus on easy sanitation. Product contact parts are easily removed without tools. The control panel is located on the first floor next to the bagging machine, so the operator can interact without climbing up to the platform.

Product from the scales passes through a metal detector from Safeline, Inc. (www.metaldetection.com) mounted just below the scale platform and above the bagmaker. The unit automatically calibrates itself as product passes through the system, tracks the pretzels and continuously compensates and updates itself for optimal sensitivity.

"The Rovema machine has done an excellent job for us," says Heffelfinger. "We run the machine very hard—twenty four hours a day, five or six days a week—and we can't afford downtime. Another advantage is the continuous-motion operation, which eliminates a lot of the tracking problems with the film and tape."

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