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Shrink wrap system provides big retail thrust

A shrink wrapper overcomes heat and packing obstacles to bundle two 24-count trays of mr. big candy bars, enabling Neilson Cadbury to satisfy Canada's retailer demand for a 48-count pack.
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FILED IN:  Machinery  > Inspection  > Metal detectors
     

"When you're this big they call you mister." The epithet for "mr. big(TM)" candy bars would be equally apropos for the bar's newer 48-count pack sold to Canadian retailers by Toronto Ontario-based Neilson® Cadbury®. While each jumbo 62-gram bar provides a point of differentiation for marketing purposes its 9 1/2" length proved burdensome for packaging. Its size had relegated the bar to a 36-count pack that wasn't satisfactory with retailers.

"In Canada retailers buy supplies about once a week" explains Robert Williams manager of capital engineering for Neilson Cadbury. "That purchase frequency means that if you sell top-selling brands in less than a 48-count pack you lose sales because the retailer may run out of product before the next order arrives.

"Then" he continues "one of two things usually happens. One you lose your shelf space and they replace your product with something else. Or two you lose sales you could have had if you hadn't been out of stock."

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Trouble was mr. big was sold in a 36-count covered paperboard box holding bars four deep and nine wide. "We wanted to get into a 48-count pack but that presented many problems" Williams notes. "With this bar being so big a 48-count box would have been impossible. It would've been either too deep too long or too wide for the retail shelf.

"And from an ergonomic standpoint our packers would've had a tough time. And then there's the added possibility of carpal tunnel syndrome injuries" he adds.

"We had tried two 24-count trays positioned end-to-end within an outer paperboard 'sleeve' but [packing them] would have been so labor-intensive that the benefits of the 48-count pack would have been offset by greater labor costs" says Williams. "As it turned out we nearly gave up getting the bars in a 48-count box. It was a dog's breakfast."

After working with machinery and material suppliers to develop alternatives Neilson Cadbury determined its best solution would be two trays each containing 24 bars shrink-wrapped into a single 48-count pack. The company uses one Model APFW 2700 XT form/fill/seal shrink wrapper supplied by Automation Packaging Inc. (Tampa FL) that was purchased through distributor Shrink Film Systems (Richmond Hill Ontario Canada).

The 48-count pack is now a reality. "We efficiently wrap 675 48-count packages a year on the API machine" Williams says. The system operates at speeds up to 12 48-packs/min.

Overcoming obstacles

While the company cold seals individual candy bar wrappers it has also gained valuable experience in heat-sealing. For example it has shrink wrapped three individually wrapped bars into a single pack. It has also shrink wrapped gift-pack boxes containing individual pieces.

"We were familiar with the problems of heat and the fact that once you reach temperatures between 80 and 85 degrees Fahrenheit you begin to melt the chocolate. As the melted chocolate cools it turns gray in color.

"Once a consumer opens the product and sees the gray chocolate he or she is not likely to ever buy that product again. So when the idea of using heat via shrink wrapping to bundle our two boxes of mr. big bars was proposed we were skeptical."

The company worked with API to overcome the heat obstacle. Williams and Saleem Ravji manager of technical packaging spearheaded that effort. The bar itself proved challenging. Besides its large size the bar is made up of peanuts covering sugar-coated wafers all enrobed in chocolate. The result is a bumpy bar that's difficult to stack.

"Along the top row of individually wrapped bars these bumps are particularly susceptible to heat" Ravji notes. "If they're exposed to too much heat they can become 'melt points.' When the chocolate melts fat comes out of the bar. That cools causing the chocolate to turn gray. To eliminate that risk and the potential of losing sales we added a micro-flute corrugated card onto the bars in the top tray." This card serves as a buffer shielding the bars on top from heat within the shrink tunnel downstream.

Another critical step was to taper the tray's top edge 1/2" on both width dimensions near the point where the two width dimensions meet the two length dimensions. If the trays were perfectly square Williams says the base of the top tray could accidentally slip into the top of the lower tray and possibly damage the product. When the top tray's slightly wider nontapered base is stacked on top of the bottom tray's tapered top edge the potential difficulty is resolved.

Rescued by wrapper

Individual mr. big bars are wrapped on an English-made horizontal flow pack wrapping machine from Rose Forgrove (St. Charles IL). This is accomplished at speeds averaging 150 bars/min. Other bar varieties are also wrapped on the line though only the 62-g mr. big bars continue onward to the API shrink wrapper.

Operators place wrapped bars in rows of eight stacking them three-high into a preglued and setup four-corner "beers" tray. Supplied by Standard Paper Box (Montreal Quebec Canada) the 125# E-flute microflute tray is litho-printed in four colors with an aqueous coating. Graphics target a teen audience with the mr. big name in large red letters against a bright two-tone yellow and gold background.

Once bars are loaded into a tray a Markem (Keene NH) unit applies an ink-jet code. This one-line code includes date of manufacture shift/machine and expiration date. Shelf life of the candy is 30 weeks. The coded tray passes through a Loma (Elk Grove Village IL) metal detector at about the same time as they're coded.

The filled trays index lengthwise onto the API's powered infeed conveyor. The conveyor advances the cases to a "pump-up" stacking assembly that elevates one tray then slides a second underneath. The top tray is positioned precisely on top of the bottom one. At this point the trays are elevated and pushed into a loading position. Next an arm equipped with vacuum cups withdraws a top card from a magazine and places it on the top tray. Also from Standard Paper Box this top card is made of the same micro-flute. It measures 10 5/8" L x 8 5/8" W. Its graphics match those on the outer box and individual bar wrap.

A transfer pusher device then moves the two-high stack into the shrink-wrapping section. Neilson Cadbury uses a 1-mil polyolefin film (it prefers not to reveal the specific resin) Vanguard 501(TM) from Shrink Film Systems; it is distributed in the U.S. through Tilden (Lenexa KS).

In operation the 36"-wide roll of film unwinds through a series of dancer rollers that help provide proper film tension. A forming plow forms the film into a tube shape. Subsequently the main pusher advances the 48-count pack into this film tube just beyond a seal bar. The seal bar jaws then close completely enclosing the pack in film. An intermittent-operating transfer conveyor then moves the film-wrapped pack onto the shrink tunnel's conveyor.

"Shrink wrapping chocolate is a very ticklish process" Williams asserts. "We did a lot of testing to come up with the right film shrink time and temperature. We use a dwell time of approximately five seconds and temperatures between 340 and 350 degrees. The clarity of this type of film also lets our graphics show through much better than standard low-density polyethylene which can look slightly cloudy. And by shrink wrapping film around our product we virtually eliminate the potential for insect infestation which is another advantage for us."

After the 48-count unit is discharged from the shrink tunnel it is transported by conveyors to a case-packing station then loaded into a corrugated shipping case sealed coded and transported to shipping on another floor. Pallet loads are trucked to seven warehouses or branch locations throughout Canada. Two of these are owned by Neilson Cadbury while the remaining five are considered "public" facilities.

"We didn't do this project to save money or to increase our packing speeds" Williams notes. "We use the API machine solely to pack the 62-gram domestic mr. big candy bar. It's performed well for us and most importantly has allowed us to get a 48-count pack out the door and better compete in our market."

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