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temporary stoppages. A novel air exchange system manages temperatures within the enclosed cooling tower. And the bakery is about to install two Fuji computer-operated robotic packaging lines. “The new oven gives us a lot of flexibility,” Mr. Nemecheck said. High-velocity, low-pressure air does the baking. The heated air impinges on the top and bottom surfaces of products in a dy▼ Line operators suggested namic airflow pattern. The installing one large mixer result is efficient heating instead of two smaller ones to and consistent crust color. make ingredient loading “This oven transfers its heat more efficient. right into the biscuits,” Mr. Edington said. The biggest difference in this oven, according to Mr. Cummings, is the design of the plenums that deliver heated air to the baking chamber. The plenums, located above and below the belt, bring hot air from the top-mounted heat exchanger units into the middle of the plenum and push it out to both side edges. Other designs bring in hot air from one side and move it across the plenum to the other side. Compared with older ovens, this system uses about 40% less fuel. The NBC oven has four heating zones. NBC chose a line that includes a pan buffer. Should a stoppage occur, the buffer gives the line operators up to 10 minutes of live storage time during production to solve the problem. The buffer also allows storage of all the system’s pans, recirculating them to the sheeter without any need for manual handling. This helps minimize pan damage. Another new idea applied to the NBC line changes the way control terminals look and function. The operations team requested a simplified approach, and engineers answered with an interface that functions as an automated run-time

▲ The heat exchangers on top of the impingement oven send hot air into plenums above and below the belt. Air moves inside the plenums from the center of the oven to its sides for even heating performance. chart. Recent history and current readings display line status in easyto-read, colored-bar line chart. Operators can access additional control screens to diagnose and adjust machine conditions. CONTROLLED PROCESS. Current schedules call for 80 hours of production per week from the new line, making both fresh and frozen products. Mr. Edington builds the line’s schedule around making fresh products first. The straight-line layout inside the new building extension allows ample floor space around the machines. (Now at 87,000 sq ft, the Nashville plant nearly fills its 5-acre site.) Although the facility has four other flour silos, the company installed a Pfening 150,000-lb silo on a separate pad right outside the expansion that houses the new biscuit line. When called for by the mixer program, flour transfers through a sifter to the Pfening weigh hopper above the mixer. Other bulk and major ingredients, including proprietary bakery mixes delivered in supersacks, enter the ingredient system through a bulk-bag unloading station. A second Pfening above-mixer weigh hopper handles these materials. A custom-built water chiller delivers ingredient water at preprogrammed temperatures. The company planned to install two mixers for this line, with the idea that spare parts would be consistent with those of the bakery’s existing mixers. During the design phase, however, the line staff suggested using one big mixer instead of two smaller ones, thus decreasing ingredient handling needs. So a large APV/BP horizontal tilt-bowl dough mixer mixer, remanufactured to NBC specs by Topos Mondial, was selected. And, according to Mr. Edington, it did indeed cut the time and energy needed for ingredient supply. Batch size is generally 2,000 lb, with a mix time of 4 minutes. “That change came from the team on the floor,” he added. “It goes to prove that it is impossible to involve too many people if you want to get good decisions.” During design, the NBC team improved worker safety in the area around the mixer by elevating the dough conveyor high off the floor, rather than running it at waist level straight from the dough pump in front of the mixer. This change improved sight lines and visibility and enables better access for sanitation. The mixer’s rubber mounts cut vibration noise. Dough moves via conveyor from the mixer to the Tromp sheeting line’s

BAKING & SNACK / September 2011

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Baking&Snack - September 2011

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