Optimizing High-Speed Shrink Wrapping of Frozen Pizzas

 

For more information, contact: 
Tom Dickman
Director of Sales and Marketing
PO Box 185, 525 Vossbrink Drive 
Washington, MO 63090
Phone: 636-239-7424
Email: tomd@texwrap.com 
To see the Texwrap pizza wrapping systems in operation, please visit www.texwrap.com.

According to the American Frozen Food Institute, 66 percent of households in the
United States consumed frozen pizza in 2010. With total sales reaching $3.2 billion
(USD) in that year, this accounts for almost 10 percent of U.S. mass-market frozen
food sales. The U.S. is the largest frozen pizza market in the world, representing
approximately 43 percent of global market value.

Shrink Wrapping Challenge

Keeping up with the demand for this very popular consumer product can be a
challenge for food processors. Not only because of the high throughputs required,
but because frozen pizza can be a difficult product to package. Few frozen food
products require more careful handling through the packaging process than pizza.
And nowhere in the packaging cycle is this more critical than in shrink wrapping.

Automated shrink wrapping of frozen pizzas has long presented significant
challenges for food processors. Delicate handling of these frozen pizza pies is
required to keep the sauce and loose toppings like pepperoni, mushrooms, sausage
and cheese intact during wrapping. These ingredients tend to shift around and fall
to the bottom of the shrink bag before sealing.

Additionally, frozen pizza being a low profile product has a high capability for
shingling while traveling back-to-back on the infeed conveyor before entering the
wrapper. Shingling prompts poor infeed registration, resulting in missed flights,
double product bagging and broken crust. When running at high speeds, such as
100 pizzas per minute, most infeed systems cannot consistently maintain accurate
indexing with the shrink wrapper.

The conventional machinery employed for high-speed shrink wrapping of frozen
pizzas – at the rate of 100 to 150 pizzas per minute – typically uses lap seal
technology for sealing the shrink bag. The lap seal method wraps the film around

the pizza as it goes through a forming shoe, then it overlaps the film on the bottom
of the pizza, static sealing it before going into the shrink tunnel. A key problem with
this sealing method is that pizza toppings will frequently fall underneath where the
seal is being made, and compromise the integrity of the seal. When the wrapped
pizza comes out of the tunnel, the lap seal can be loose or open, but it is very hard to
detect. Usually it is the customer who discovers that the pizza they purchased has
not been securely sealed.

To achieve a better quality seal on frozen pizzas, food processors have utilized
continuous motion side-seal shrink wrappers. These systems allow a continuous
incoming stream of pizzas through the wrapper while a side-seal is generated,
followed by an end seal which separates each package before entering the shrink
tunnel. Because the seal is being formed on the edge of the pizza, rather than across
the bottom, the danger of loose toppings contaminating the seal area is eliminated,
resulting in a much more reliably sealed package.

Conventional continuous side-seal wrappers, however, have a limited speed range.
They are useful up to about 100 pizzas per minute throughput, above that and their
quality output diminishes. Consequently, many frozen pizza producers have opted
for lap seal wrappers to achieve the higher throughput, despite the loss in seal
quality.

Palermo’s Pizza’s High-Speed, Side-Seal Wrapper Line

Now, a new generation of continuous motion side-seal shrink wrapper for frozen
pizzas provides the benefits of a secure seal combined with a high-throughput
capability. Palermo’s Pizza is one frozen pizza manufacturer that is utilizing this
latest continuous side-sealing technology.

Based in Milwaukee, Wisconsin, Palermo’s Pizza was started by Sicilian immigrants
Gaspare and Zina Fallucca who opened an Italian bakery on Milwaukee’s east side in
1964. The bakery expanded into a full-service restaurant known for its pizza, and
by 1979 they began to manufacture and sell frozen pizzas based on their family’s
traditional Sicilian recipes.

Palermo's is an innovator in the frozen pizza category, creating the industry's first
self-rising frozen pizza and its first ultra-thin crust product. It manufacturers
a family of frozen pizzas under the Palermo’s brand including products such as
Primo Thin™, Naturally Rising™, Stone Baked™ and Classics by Palermo’s™. The
company continues to research and develop new products and flavors that cater
to consumer needs, such as its recent introduction, Palermo’s Hand Tossed Style™,
which features ‘family-favorite flavors’ on a middle-thickness crust.

The popularity of these brands has made Palermo’s one of the fastest growing
manufacturers of frozen pizzas in the United States. To meet the demand for its
products, the company recently expanded its headquarters and manufacturing
facility. Opened in 2011, its new 250,000 square foot state-of-the-art USDA

manufacturing plant is a showpiece of packaging technology, operating four
packaging lines for handling its frozen pizzas. But, central to Palermo’s packaging
operation is its main packaging line, for handling its top-selling 12-inch frozen
pizzas.

Prior to reaching that packaging line, sauce and toppings are deposited onto dough
to form the pizzas which are then put through an ammonia-based spiral freezer.
Exiting the freezer, the now frozen pizzas are conveyed through the shrink wrapper
and shrink tunnel, then on to labeling and cartoning. The product is then cased,
palletized and sent off to shipping or deep freeze storage.

“We have been experiencing continued growth at a double-digit rate every year,”
says Mike Walz, Vice President of Operations for Palermo’s Pizza. “As we grew and
the demand for product went up, it generated a need for us to operate at a higher
level of speed to meet the demand.”

“The challenge that we were facing as we tried to push our line speeds up was
the ability of our existing lap seal wrappers to run at the higher rate of speed,
and provide a reliable seal,” continues Walz. “The lap sealers use a static sealing
process. It is an overlap on the bottom of the pizza. Sometimes we would lose that
seal, and in the shrink tunnel that would open up. That tended to be limiting factor
when running at higher speeds.”

“On our main packaging line we were using a lap sealer that was operating at less
than 90 12-inch pizzas per minute,” explains Walz. So, we embarked on a project to
increase the line rate on that line first. After reviewing several shrink wrap designs,
we settled on one system that could be custom configured to meet our specific
needs, instead of adapting to an existing format.”

The system that Palermo’s selected is a high-speed, continuous motion, servo-
controlled side-seal shrink wrapper, from Texwrap, a leading designer and
manufacturer of fully-automatic shrink wrapping systems. What makes this system
so unique is its utilization of multiple technologies which are integrated into one
system architecture, enabling high-speed throughput of up to 150 frozen pizzas per
minute with consistent high-quality seals and without damage to the fragile pizza
products.
 
The throughput speed of the wrapper is achieved by the sealing head, which is
a patented servo orbital-motion technology. It eliminates the need for the head
to move with the product while the seal is being made. The sealing head moves
in an ellipse, without the back and forth motion of typical sealing heads, which
dramatically increases the throughput speed of the wrapper.

The orbital head is controlled by very fast and precise servo motors, as is the entire
wrapper and infeed. The system is built with Generation 3 servo technology,
meaning that it was designed from the ground up to integrate servo technology,

PLC control and the mechanical elements of the system. The system’s 10-axis servo
controls provide extremely accurate registration, minimize the amount of film used
for wrapping, and reduce the need for maintenance.

Palermo’s wrapper is equipped with a product protection system which ensures
that the orbital head will not close down on any pizza. A sensor maps the position of
each pizza as it enters the orbital head operating space, and knows when a pizza is
misplaced, skipping that seal cycle.

“We tested the wrapper at 180 pizzas per minute,” Walz says. “This is very fast
throughput. But it performed as expected, with accurate registration and secure
seals, and no product damage. On a continual basis, we normally operate the system
at 120 – 140 pizzas per minute, considerably faster than the maximum 90 pizzas per
minute with our prior lap sealer.”

Sealing film securely at such extreme speeds requires a very special side-seal
design. The side-seal on this system uses the patented Green Machine technology
invented by Shrink Packaging Systems Corp. During sealing, belts grip the film
securely over a long distance allowing the seal to be made on the pizza and the
trim to be cleanly separated. A special heating element seals and separates the
film between them. The system is self-compensating. As wrapper speed increases,
the film stays in contact with the heating element longer, eliminating the need
for constant adjustment. Because the film-gripping belts allow the tension on the
film to be isolated from the sealing process, the result is consistent seals using
the absolute minimum film width. In addition to superior control of the elements
needed for great seals at speed, the other advantage of Green Machine technology is
that its simplicity virtually eliminates the maintenance associated with most side-
seal designs.

The infeed is optimized, as well, for maximized throughput and careful product
handling. A Texwrap-designed lane-combining system takes three lanes of pizzas
exiting the freezer and consolidates them into one lane. Then, a servo-driven flying
nose bar is programmed to not only place the pizzas inline at a set spacing without
touching each other, but also to automatically adjust the speed of the entire line
to match incoming production. This ensures that pizzas do not shingle, keeping
toppings and crusts intact, which is critically important at throughput rates of 150
pizzas per minute. Following, a lug conveyor automatically inserts a cardboard
circle underneath the pizzas, and indexes the product into the wrapper.

The wrapper’s infeed is a totally integrated system that self-adjusts to incoming
production. As the pizzas slow down or speed up, so does the entire wrapping
system.

To support the shrink wrapper, Palermo’s installed a Texwrap triple-chamber
forced air convection tunnel, equipped with digital temperature controls, high
velocity fans, individual top and bottom controls for air direction, and variable-

speed conveyors. These features control the right amount of heat to be put in the
right places, over the correct amount of time to produce consistent shrink results.

The heat tunnel incorporates a feature called Seams Down, which ensures that the
side-seal seams do not position over the printed circular label on top of the pizza.
When shrink wrapping pizza, the seam can potentially climb up past the center
top of the pizza and obscure the label on the top. By directing the air inside of the
tunnel to make the film on the bottom of the pizza shrink before the film on top, this
condition is avoided.

Palermo’s entire infeed and shrink wrap system is designed to be sanitary-friendly.
Rated for heavy wash down, the corrosion-resistant, welded stainless steel design
eliminates crevices and areas where food could collect. The conveyors incorporate
quick-disconnect removable sections for easy cleaning, and fall-through design so
food debris will not get trapped.

Performance

“Knowing the inherent design of both the static lap seal and the continuous motion
side-seal, the speed and the quality of the seal is tremendously improved with the
continuous system,” explains Walz.

“We were able to get a shrink wrap system on our primary line that not only met
our design specifications, but exceeded it,” continues Walz.

In the highly competitive frozen pizza market, high volume production with near
zero defect rates in packaging is critical to profitability. Those manufacturers that
embrace advanced shrink wrapping technology to streamline packaging throughput
will be in a better position to run efficient manufacturing plants and reduce
operating costs.

About Palermo’s Pizza

Palermo's Pizza is a brand of frozen pizza manufactured by Palermo Villa Inc. of
Milwaukee, Wisconsin. The company has been making quality, Italian style frozen
pizzas since 1979. What began as a small ethnic bakery in 1964 featuring authentic
Italian pizza has become a leading name in the frozen pizza industry.

Palermo's frozen pizzas are available at grocery stores and big box retailers in
almost every state. The company also distributes its pizza products in Canada.

To find out more, contact Chris Dresselhuys, Director of Marketing, Palermo Villa,
Inc.; 3301 W. Canal Street, Milwaukee, WI 53208; Phone 414-982-6322; email
c.dresselhuys@palermospizza.com; www.palermospizza.com.