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Cheese bagging with a twist

In-line cheese-bagging systems at Mullins Cheese accept blocks of product made in a set of towers and churn out two packs/min.

A family-owned operation in business since 1970, Mullins Cheese, Mosinee, WI, is producing blockbuster results with its new cheese block-packaging/handling equipment from Sealed Air's Cryovac Food Packaging Div. ( A commercial cheesemaker that specializes in producing cheddar, Colby, Monterey Jack, Jacko (marbled) and Parmesan cheeses, as well as “the best Wisconsin cheese curds around,” according to promotions on the company's website, Mullins sells most of its cheeses in bulk 40-lb blocks to large cheese processors' cut-and wrap operations coast to coast that repackage the cheese under various brand names and private labels. It also sells through foodservice companies and sells smaller portions of its cheese in its bustling retail store and has another cheese-production facility in Marshville, WI, that makes 640-lb blocks of cheese.

Big changes in cheese

Cheesemaking and packaging processes at Mullins have really changed in the last few decades, with more automatic equipment being added all the time. “I remember when we made all of the cheese in the same vat,” recalls Bill Mullins, one of the owners of the company. “We would manually pour the milk into the vats, manually coagulate it, cut it and drain it all in the same vat, pail it out by hand and them put it in forms and seal everything in waxed paper and, before that, in wooden boxes. There was so much manual labor.”

With its cheeses shipped to some 80-plus customers coast-to-coast, Mullins goes through a whopping 1.1 million lb of milk per day. That milk is collected from 900 dairy farms. So Mullins is automating things considerably.

But despite the large volumes and the changes it has made, its block-cheese packaging operation was still a bit more labor-intensive and time consuming than it would have liked. Mullins' workers had to manually load the 40-lb blocks into bags, after the blocks were formed, which was a time-consuming and back-straining task.

Automatic bag loaders seemed to be the next logical move in Mullins' packaging operation. So in August, 2007, Mullins added six of Cryovac's Model CL-20 bag loaders—a solution that has made better use of employees' time and keeps the production lines humming more efficiently. Cryovac designed the CL-20 bagger to enhance operational efficiency, and Mullins knew that automating its loading process could help streamline the operation.

“We use other Cryovac equipment for our cut-and-wrap products and have their vacuum chamber and their barrier bags, so adding bag loaders was the logical next step,” Bill Mullins adds. “We began adding some new equipment last year. Cryovac showed us a video of the CL-20 system running, and we thought it was very unique.”

Recalls Stan Johnson, a Cryovac sales representative for the Northeastern Wisconsin region: “We approached Mullins Cheese about bag-loading systems and after several years of consideration, it chose the CL-20. The driving force behind the decision was labor savings.”

Bill Mullins agrees. “It's not only a real labor-saver but it cuts down on a lot of waste. We found out that our cheese towers run much cleaner than before and looked at the return on investment and realized it would really be worth it. The machines are very efficient. We are probably saving about 200 pounds of cheese a day in waste.”

The new bag loaders were installed in a straightline setup within a week's time, in place behind its six cheese blockforming towers. Earlier, two operators had to load the cheese into bags and run the towers. Now, the operators can perform other tasks while the patented CL-20 systems accept the large blocks of cheese from the towers and pack them automatically into premade bags (made of gusseted nylon-based film and also supplied by Cryovac) up to 25.5 in. wide and 19 in. long. pulled from the machines' stainless-steel cassette. Designed with plug-in modules for quick servicing and product changeovers (though Mullins only uses the machines for the 40-lb size blocks only), the systems operate at speeds up to 2 bags/min, saving what Bill Mullins says is a significant amount of labor versus the previous manual bagging method.

The blocks of cheese are “injected” into the bagger's chutes and directly into the opened, gusseted bags.

The removable bag cassettes each store more than 300 bags—enough for at least four hours of unattended operation, depending on tower cycle times. The machine door can be opened so that an operator can load the bags onto spreader plates, which are activated by a start/stop button on a control interface. A warning light on the door tells the operator that a bag cassette is about to run out of bags.

The company likes that an empty cassette can be easily removed and replaced with a fully loaded one. “We're bagging on six machines that hold 1,800 bags at a time,” Bill Mullins says. “We go through about 5,500 blocks of cheese each day, so the cassettes work well.”

Designed with simplicity and modularity in mind, the loaders maximize uptime and ease maintenance. The CL-20 is integrated with the block towers' control panel. Operator-interface options include a dedicated alphanumeric display with centrally displayed status and diagnostic information.

Mounted inside the door are two panels that house pneumatic and electric controls that allow for easy access and are protected in harsh washdown environments.

Turner, regusseter added

To eliminate pinch points with neighboring conveyors and to improve product flow, Mullins also added Cryovac's UBT20 block turner to the operation, which Cryovac designed for use on bulk-cheese production lines to smooth rotation of the cheese by 180 degrees so that the blocks align properly with the seal bar of a three-compartmented BetaVac® vacuum-chamber vacuumizing system. Distributed by Sealed Air, the BetaVac accepts three blocks of cheese at a time. The turner works in conjunction with a Cryovac RG-20 bag-regusseting machine that automatically folds and prepares the bags for vacuumizing and sealing on the BetaVac.

Explains Cryovac's Kirk Huxtable, technical sales representative for the Northeastern Wisconsin region: “One end of the bag is gusseted at the factory. The open end must be refolded properly so that there that no wrinkles are present in order to create a proper seal in the Betavac system.”

Packaging begins once the cheese is ejected from the cheeseforming towers, and the blocks convey to the six in-line bag loaders without human intervention. The bag loaders then pneumatically lift the loose bags from their cassettes using a pickup device and transfer them into a guide chute that releases them so that the open end of the bags easily slide into a bag-opening mechanism.

Cheese packing in action

The opening device has an upper and a lower section and applies vaccum to both top and bottom faces of the bag. The lower section swings into position and presents the bag to grippers that apply vacuum to side faces of the bag. Spreader plates align with these grippers and the bag and the gripper travel over the spreader plates, which spread apart to open the bag. The spreader plates and the bag then lower into position for the block of cheese to be inserted from the tower, which takes about 6 to 8 sec, depending on the type of tower and its speed. A red light on the top of the loading machines flash to let workers know when the system is low on bags.

After the block of cheese has been inserted into the bag, the bag is pushed onto an eject conveyor to the UBT20 turner, which has tall guards that fit the height of each cheese block, and can be easily lowered to gain access to maintenance and cleaning. The turner is controlled by the RG20 regusseting machine constructed with all critical parts treated to withstand corrosion. The regusseter cycles every 9 sec and refolds and prepares up to 360 bags/hr.

“The regusseter gives our bags a smooth finish,” Bill Mullins explains. Next, the bags are vacuumized and heat sealed, which protects the cheese from oxygen and helps retain its moisture levels while reducing trim waste from mold growth.

The finished, sealed bags then convey through a Cintex metal detector from Loma Systems ( before they're case-packed a new case erector/packer/sealer that Mullins added to the end of the line.

Made by Massman Automation Designs (, the wraparound packer can reach speeds as high as 42 cpm, but at Mullins assembles corrugated blanks into cases automatically before glue-sealing them at rates of about 12 blocks/min. The cases of cheese are then palletized in-line, 54 cases/load, on an existing palletizer from A-B-C Packaging Machine ( and the loads are stored in a cooler before being distributed throughout the U.S. The cheese line operates three shifts (20 hr total) a day, six days a week and produces about 330,000 lb of cheese each day. Bill Mullins praises the equipment and says it has made the firm more productive.

“We have already seen a return on our equipment investment,” he points out. “We saw it on Day One because we save two people per shift that packed cheese, so that's quite a bit of labor. The new machines are very low-maintenance and are reliable. We've really improved our efficiencies and the loaders give us very good-looking blocks of cheese. As far as sales are concerned, they'll go up as long as we can keep pace. So we're very pleased.”

More information is available:
Cryovac Div., Sealed Air Corp. 800/391-5645.
A-B-C Packaging Machine Corp., 727/937-5144.
Loma Systems, 800/872-5662.
Massman Automation Designs, LLC, 320/554-3611.
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