Flour Mill Automation: Millstones to ABB Palletizers

A flour mill is a long chain of machines: grain cleaning, grinding on roller mills, sifting, then packing and bulk loading. Flour mill automation began at the grinding end more than two centuries ago and reached the warehouse much later, where paper sacks still have to be filled, stacked and wrapped. This post follows the trade from millstones and Oliver Evans' automated mill to roller mills and the first palletizing robots. Then it turns to the mills that opened this autumn and to the dust rules that decide where ABB's palletizing robots could fit.

Women fill and handle sacks of flour under the packing spouts at the Rank and Sons mill in Birkenhead, September 1918. Photo: George P. Lewis, Imperial War Museums via Wikimedia Commons (public domain)

How millstones gave way to elevators and rollers

For centuries flour came from a pair of millstones. Sacks of grain were hoisted to the top floor, the grain fell through a hole in the turning runner stone and was ground against the fixed bed stone, and the flour left at the rim and ran down a chute into sacks. Oliver Evans set out to change that labour-intensive routine in Delaware. A mill his brothers built on Red Clay Creek opened in 1785, and Evans added a bucket elevator and the hopper boy, a rake that spread meal on the drying floor so nobody had to shovel it. In 1789, working with Jonathan Ellicott, he turned the Archimedean screw into a horizontal conveyor.

The hopper and slipper that feed grain into the millstones at George Washington's Gristmill, Mount Vernon, Virginia. Photo: Kadin2048 / Wikimedia Commons (CC BY-SA 3.0)

Evans received the third US patent under the new federal law in 1790 and published The Young Mill-wright and Miller's Guide in 1795. His machines carried grain from one stage to the next without hands, which his Wikipedia biography calls the first fully automated industrial process. Mills grew huge in the next century. Cadwallader Washburn's A Mill in Minneapolis was declared the largest flour mill in the world when it was completed in 1874. On 2 May 1878 a spark ignited airborne flour dust and the blast destroyed it, killing 14 workers, and the fire that followed killed four more people and cut the city's milling capacity by a third. Mills across the country then fitted ventilation and other safety devices.

A stereograph of the ruins of the Washburn A Mill in Minneapolis after the flour dust explosion of 2 May 1878. Photo: William H. Jacoby, Hennepin County Library via Wikimedia Commons (public domain)

Grinding changed with the roller mill. Practical roller mills arrived in the 1800s, Friedrich Wegmann developed porcelain rollers in the 1860s, and the Hungarian engineer András Mechwart built on his ideas with a design that spread through Europe and the Americas. Modern mills spin steel or cast iron rollers, though many bakers still prefer stone-ground flour. Robots came in at the packing end. Molinos Rio de la Plata, founded in Argentina in 1902 as a wheat miller, first turned to ABB robots in 2008, because loading 7.5 to 10 kg sets of bagged pasta onto pallets by hand had caused recurring injuries on its older lines.

An old Bühler system roller mill kept at La Perla, a former flour factory on the Canal de Castilla in Valladolid, Spain, 2018. Photo: MiguelAlanCS / Wikimedia Commons (CC BY-SA 4.0)

New mills and robot sack lines in 2026

Most of a new mill already runs itself, as Mauri's plant in Ballarat, Australia shows. The division of George Weston Foods finished the 530 tonne-a-day mill this year for more than A$200 million, and the first flour went to customers in August. It has 19 Arrius roller mills from Bühler, in-line near infrared analyzers and enough automation for mostly unattended, lights-out running, and it uses 40 percent less energy than the North Melbourne mill it replaced. Its 2,800 square metre packing and warehouse building holds a Fawema paper sack filler, an Ehcolo palletizer and a pallet hooder. In Ireland, which imports about 260,000 tonnes of flour a year, Slaney Flour has just broken ground on a 300 tonne-a-day mill in County Wexford.

A Bühler MDDR Antares roller mill, 2008. Bühler supplied the milling equipment for Mauri's new mill in Ballarat. Photo: Bühler Group / Wikimedia Commons (CC BY-SA 3.0)

Some mills already let robots stack the sacks. In 2022 Ocrim's FBC department reported a line for Les Moulins Advens in Strasbourg that handles 10 and 25 kg flour bags. A robot places each bag in a compactor trolley that presses and arranges it on the pallet, after a metal detector and a checkweigher have rejected any bag that fails. At Harinero Sula in Honduras, two robots side by side take 50 and 100 pound bags from one overhead conveyor. Finding people is getting harder too. Bühler told World Grain in September that staffing is one of the industry's greatest challenges, because fewer people want to work in a mill or know how to run one efficiently.

The ABB palletizing cell at Molinos in Argentina takes bags from conveyors and builds pallets. Photo: Eduardo Gil / ABB

We could not find an ABB robot in a flour mill, but ABB built its palletizers with bags in mind. The IRB 460 is a four-axis robot that ABB sells for end-of-line and bag palletizing, with a 110 kg payload, a 2.4 m reach and up to 2,190 cycles an hour with 60 kg. The larger IRB 660 carries 180 or 250 kg over a 3.15 m reach. At Molinos's Lucchetti pasta plant, an IRB 660 stacks bags from two conveyors and lays kraft paper between layers. Molinos planned that cell for three months in RobotStudio's Palletizing PowerPac and says it saved six to eight months of debugging. Our post on pasta production covers that line.

An ABB IRB 660 robot stacking bags of Lucchetti pasta on a pallet at Molinos in Argentina. Photo: Eduardo Gil / ABB

Dust rules and the next robot cells in mills

Dust is the hard part. In a Robotics Tomorrow article this month, Bram Renkema of the Dutch robot converter Ramtec notes that flour can form explosive atmospheres, that EU directive 1999/92/EC requires such areas to be classified into zones, and that palletizing bagged flour at the end of a line is one place where a robot's work envelope can sit inside one. Ramtec went through all 85,102 IECEx certificates as of August 2026 and found 65 covering robots, 42 of them for painting. For palletizing in a Zone 21 or 22 dust area the register offers little, so plants either convert and certify a standard robot or keep it outside the zone.

A flour dust explosion demonstration: flour dispersed by compressed air and ignited by a detonator, 2009. Photo: Hans-Peter Scholz / Wikimedia Commons (CC BY-SA 3.0)

So an ABB cell in a flour mill is still only a possibility. The IRB 460 and IRB 660 are sealed to IP67, ABB pairs the IRB 460 with its FlexGripper Claw for bags, and a mill could test stacking patterns in RobotStudio before building anything, as Molinos did. Mills like Mauri's already run mostly unattended, so a robot at the end of the line would have to fit that model, with the sack filler, checkweigher and hooder around it. IP67 sealing is not an IECEx or ATEX certificate, though, and the site's own zone assessment decides whether a standard ABB robot can stand in the packing hall at all.

Engineers share a robot cell design through RobotStudio Cloud, the kind of model a mill could use to test stacking patterns. Photo: ABB

For home bakers the trend runs the other way. On 15 October Cairnspring Mills opened its Blue Mountain Mill, a stone mill on the Umatilla Indian Reservation in Pendleton, Oregon, and its premium flours are popular with home bakers. At full speed it will mill more than 115 million pounds a year, which its chief executive says the big mills make in about two weeks. Large mills face the cost question instead: Mauri's new site took five years from conception to commissioning. Skills are another limit. GoodMills, which runs 25 mills in seven countries, lists skilled labour shortages among the reasons it is digitalising its plants.

A homemade sourdough loaf cooling on a wire rack. Home bakers are among the buyers of premium stone-milled flour. Photo: Dana Hutchinson / Wikimedia Commons (CC BY 3.0)

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