According to Bruce Hoshor, plant manager at Avon for nine years until a recent promotion, there were times during the mill's history when its position within General Mills was not readily apparent. Built in the 1950s to incorporate the innovative Bellera milling technology, the plant initially was meant to supply flour to customers in the Chicago area.

   When General Mills closed many of its mills in the 1960s, the Avon mill attracted considerable management scrutiny, Mr. Hoshor said. After all, a mill near Des Moines does not rank neatly as a destination mill, since it is not near major population centers. Similarly, it could not be described as an origin mill since little milling quality wheat is grown in Iowa. On more than one occasion, Mr. Hoshor recalled, management considered closing the facility.

   In 1992, the decision was made to build a consumer mix plant adjacent to the mill. General Mills had previously acquired the Robin Hood consumer mix brands from International Multifoods Corp. General Mills decided to bring production in-house, and Avon was chosen as the new mix plant location.

   In 1996, the mix plant's capacity was increased.

   While the mix plant has been important to the success of the Avon mill, it is far from the dominant factor, since only about 10% of the mill's flour now is used internally. Other factors have made the mill's location in the middle of "corn country" an attractive one.

   One of these is the rising importance of truck shipments in the 1990s, which accentuated the importance of the plant's location near Interstates 35 and 80. Throughout the 1990s, the mill has operated at or near its daily milling capacity of 6,400 cwts.

   Still, justifying an expansion or modernization to corporate management was not easy, even as the original Avon mill approached 40 years of age. "We would not have been able to justify a $12-million project just because the equipment was getting old," said Peter J. Moberg, systems engineer at the Big G cereal plant in Cedar Rapids, Iowa. Mr. Moberg was project engineer and safety coordinator of the Avon expansion.

   Ultimately, a number of factors worked in the mill's favor, Mr. Hoshor said. Its location allows the plant to move product economically as far south as Texas and Florida and as far north as Michigan, he said.

   Being situated on a 45-acre site means the Avon mill has plenty of space for expansion, which Mr. Hoshor called a "luxury" in comparison with site limitations at other General Mills locations.

   Grain storage also proved an important factor in making the expansion decision. The million-bu grain elevator at the site gave the mill more than enough storage to accommodate the capacity expansion.

   The grain elevator at Avon was not built with the original A-mill in 1957. The entire focus of the initial project was on perfecting the Bellera process, and grain storage was almost an afterthought (see related story below). It initially consisted of a few small bins just outside the building. Wheat storage was so inadequate in those early years that the mill often operated "hand to mouth," from train to train, Mr. Moberg said.

   It was in 1959, when the B-mill was installed and capacity doubled to 4,000 cwts daily, that a million-bu elevator was built.

   The small grain bins next to the building were essentially redundant for almost 40 years. Yet, these bins ultimately proved pivotal in making the expansion possible (see story on Page 23).

    "There were intangibles, too, such as the excellent quality of the labor force here," Mr. Hoshor said. Ultimately, the plan for Avon was termed a "growth project" by the company and the decision was made to expand the A-mill from 2,800 cwts. daily to 7,500 cwts. "Running year after year, seven days a week, our sales people were confident they could sell more," he said.

   After weighing a variety of options, the company decided to modernize the A-mill within its existing structure and with virtually no interruption in operations. Buhler, Inc. was selected as the primary equipment supplier for the expansion.

   Long before the modernization began, Mr. Moberg, Mr. Hoshor and Brent S. Johnson, manager of the mill and elevator, traveled around the United States and Europe to look at design possibilities. "One of the attractions of the mills in Europe was their immaculate condition," Mr. Hoshor said. "We asked, ‘Why can't we do that?' And that is exactly what we are doing here."

   Mr. Moberg agreed. "One of our objectives was to create a mill as sanitary and aesthetically attractive as any in Europe," he said.

   To achieve this, interior designers were consulted to help select colors — nothing fancy, but simple clean colors that the mill's many visitors would find appealing. Some of these "finishing touches" are still being applied.

   For automation, General Mills opted to "go as far as was economically justified," Mr. Hoshor said. The unit is a suspension mill, meaning that when a problem arises, the entire mill does not need to be shut down and then restarted. At 7,500 cwts a day, the A-mill's capacity has been more than doubled with no additional personnel.

   The new mill grinds primarily spring wheat with small quantities of hard winter and soft red for consumer mixes. "The company has focused on building business with artisan bakers, many of whom prefer flour milled from spring wheat," Mr. Hoshor said. Spring wheat is received in unit trains, while soft red is trucked from Missouri.

   Although not a "lights out" mill, Avon does have a number of stand-out technical features. Spouting at the mill is made from stainless steel, which Mr. Johnson said obviates the need for painting and lessens long-term operating expenses.

   A system of Buhler "gather-up" conveyors allows the mill to segregate or isolate any flow within the mill. "When a flour quality issue arises in a traditional mill, determining its source can be difficult," Mr. Moberg said. "The gather-up conveyors let you identify exactly which of the 47 streams is at issue — first break, second break, first sizing or whatever. It makes trouble-shooting easier."

   A relatively low-tech but still eye-catching innovation at the Avon mill is digital readouts at prominent locations throughout the facility, hooked up to the control room's diagnostic screen. If a problem develops at the mill, operators don't have to run long distances to the control room to figure out what is happening. Instead, by glancing at the nearest digital readout, the situation may be instantaneously assessed.

   An unusual feature of the mill, one embraced for sanitation and economy, is its tube-steel construction, fully welded and sealed. With no masonry, less expenditure on support footings was needed. More important, harborage points for insects were eliminated, Mr. Johnson said.

   Existing I-beams were enclosed for the same reason. "We didn't want hiding places anywhere in the mill," Mr. Moberg said. "Everything was designed with sanitation in mind." Mr. Hoshor said heat sterilization may be used in the future at the mill.

   Another unique feature incorporated with sanitation in mind is the design of the tempering bins. "Most tempering bins are inverted cones," Mr. Moberg said. "These have no internal structures — no ledges and no choke-up," he said.

   Milling equipment supplied by Buhler included six double-high MDDL rollstands on the breaks and the tail end, and eight single-high MDDK rollstands for the balance of milling. Sifters are all made of metal — a first for General Mills — with three eight-section sifters, Novastar sieves and one six-section rebolt sifter.

   The flow also incorporates four Buhler double triple-deck purifiers, six Buhler bran finishers and seven detachers.

   The cleaning house features a Buhler grain classifier, a Combinator, which is a combination concentrator and destoner and a Heid cylinder separator. A Sturtevant impact mill, three closed circuit Buhler aspirators, and a Buhler horizontal grain scourer finish out the cleaning system.

   Tempering features a Buhler tri-rotor dampener and Buhler auto tempering system that tests on a continuous basis, detecting moisture and readjusting water flow to reach a set point. "You don't have to wait until the wheat hits the mill to find out whether you tempered properly," Mr. Johnson said. "You make sure ahead of time."

   Another improvement incorporated is replacement of flex hoses that would be moved from bin to bin in bulk flour storage with 32 two-way diverter valves automatically moving flour into the appropriate bins after rebolt.

   A Buhler Sterileter also is used before flour goes into bulk storage. "Because it is a blow-through device, it helps conserve space," Mr. Johnson said.

   Ingredient feeders for blending are operated through the Allen-Bradley programmable controller at the heart of the mill's automation. Programming was handled by Greenway Electric, which also did the mill programming and put together control screens. Based on the grade of the flour, appropriate ingredient feeders are turned on.

   The diverter valves, the ingredient feeders and the gather-up conveyors all are elements of the design aimed at giving General Mills "complete and exact control in meeting specifications," Mr. Moberg said.

   Mr. Hosher said, "This mill accommodates a wide range of flour grades and specifications. With branded sack business, we need maximum flexibility, which is one of the reasons we ruled out a short flow system when we considered various alternatives for the project. It does not provide maximum flexibility."

   Serving an existing customer base proved very helpful for General Mills in prioritizing features for the new flour mill, Mr. Johnson said. "It's only been a few months, but we really haven't heard, ‘Gee, I wish we would have thought of that,' " he said. "Sanitation, yield and capacity are our targets, and each step of the way as we made our decisions, we would reflect on these issues. It greatly simplified decision-making."

   The entire expansion project was completed in 16 months, two months ahead of schedule, an achievement Mr. Moberg credits to consistent and clear communications throughout the process. Weekly and biweekly conference calls were conducted with contractors and equipment makers, and daily construction meetings were held with workers, from electricians to painters, to make sure efforts were coordinated.

   "At times, we had more workers and contractors here than we had mill and mix plant employes," he said. Buhler, Inc. maintained staff on site during the project to be sure equipment was properly installed.

   Other participants in the project included millwright work by Borton, Inc., Hutchinson, KS, and engineering by Van Sickle, Allen & Associates, Inc., Minneapolis.

   "Speaking for ourselves, if we had to do it again, we would use the same people," Mr. Moberg said.

   The company may have the opportunity. While no plans have been made regarding the future of the B-mill, Mr. Hoshor said that continued growth in demand for flour from Avon could necessitate taking a close look at another capacity expansion there before long.

— L. Joshua Sosland