Roll refurbishment

Keep on rolling

Efficient production not only hinges on people’s expertise, but also on well-maintained technology. In food and materials processing environments, roller mills are subject to continuous wear and tear. Properly timed roll refurbishing is crucial for ensuring consistently high product quality and cost optimization. Bühler offers this vital service in dozens of locations around the world.

In industries ranging from grain milling to brewing, malting, oilseed processing, animal feed production, chocolate manufacturing, and the grinding of materials for inks or battery slurry, roller mills are a crucial component. The condition of these rolls – fluted or smooth, recently installed or in use for over a decade – directly impacts their performance.

However, without regular maintenance, even the most advanced rolls cannot operate at their peak efficiency. In fact, production capacity drops significantly, while energy demand can increase by up to 50 percent. In times where every grain counts, the milling industry is particularly vulnerable to inefficient processing of grains – and, as a result, they are at the forefront of combining learned nuances with state-of-the-art technology.

Want to learn more about roll refurbishment? Watch this 60-second video.

“When they are properly serviced, the rolls’ cutting angles act like a fillet knife. In a flour mill, that is how they open the wheat kernel. Through each break the angles change, allowing a scraping action to accurately peel off the endosperm from the bran,” explains Bill Ritchie, Technical Sales and Service at Bühler North America. He spent the better part of 2023 visiting 212 milling plants in North America to better understand customers’ needs in terms of their rolls. “If the cutting angle begins to wear, it will not cut correctly and will inhibit the miller’s ability to set the rolls properly. The process will change from a cutting action to a crushing action. This not only requires more energy; it also fails to deliver the right kind of granular product.”

That’s why regular check-ups are the prerequisite for determining when rolls must be sent for refurbishing. In a wheat mill, for example, manual checks of the flutes are a standard task of any miller. With their experience, millers around the world have developed a keen sense for literally checking the quality of flutes with their fingertips. While such checks are a good first indicator for wear and tear and there are other manual measuring tools and many tips and tricks millers apply, high-end machinery should be examined with high-end tools.

Taking out the guesswork

Bühler has been introducing digital solutions to its technologies for years to harness the full potential of digitalization. The temperature and vibration management (TVM) service is a prime example. It provides basic information about the parallelism of the grinding gap and early indications of wear-related issues. Nowadays, TVM is able to draw sophisticated conclusions. This includes, for example, feed gap analysis or cambering insights as a basis for predictive maintenance.

Such analysis provides a huge advantage to a flour miller. In the case of fluted rolls, the yield of pure flour extracted during sifting can drop by two or even up to four percent if the rolls are blunt. Both throughput and yield decline. A flour mill with a production capacity of 400 tonnes per day experiencing a drop in yield of only 0.1 percent will incur a loss of revenue of approximately USD 12,000 a month (based on US market prices).

We recondition rolls from a variety of applications in the flour milling, animal feed, cocoa, and malting industries. In 2023, we provided roll reconditioning services to customers in 24 countries.

Axel Kasper, Head of Processing, Bühler Braunschweig

Energy consumption may rise by as much as 50 percent, while moisture content declines and the quality of the final product suffers. “This is significant in terms of the economics involved, but it is also a question of sustainability. If you can maintain a consistent grinding performance, you are able to save up to 50 percent energy per grinding passage. The same principle applies for brewing and for animal feed plants. Keeping rolls in top condition means less waste and more profitability,” explains Gernot Stoerr, Head of Product Management Milling Solutions at Bühler Group.

Once the customer and the local Bühler expert determine that it’s time for roll refurbishment, the rolls make the trip to one of the company’s dozens of service stations in Europe, Asia, and North and South America. Bühler offers a range of services for both fluted and smooth rolls, grinded rolls for cocoa production and the grinding and dispersing industry, but also dies for processing animal feed, and tensioning and framing of sieves.

One of the largest service stations is located in Braunschweig, Germany, where Axel Kasper, Head of Processing, and his team provide their magic touch to around 3,000 rolls each year for customers from all over Central and Northern Europe. “We recondition rolls from a variety of applications in the flour milling, animal feed, cocoa, and malting industries. Depending on the requirements of our customers and the type of roll, this takes between one week and several months. 

WAFA high speed WAFA high speed The WAFA high-speed corrugation machine was developed by engineers at Bühler Braunschweig exclusively for the service station. It corrugates fluted rolls at a speed of 120 meters per minute in both directions.

Bühler’s service stations

Bühler operates a network of 105 service stations on five continents to cover customers’ needs in the Advanced Materials and the Grains & Food businesses. Talk to your local Bühler representative to discover how our service portfolio can help you extend the lifetime of your Bühler equipment and get the most out of your process..

Hima Hastriando, Hima Hastriando, Hima Hastriando, Polymechanic at Bühler, inspects a roller mill. Consistent grinding performance can save up to 50 percent energy per grinding passage.

In 2023, we provided roll reconditioning services to customers in 24 countries,” says Kaspar. The corrugation of roller mills is a specialty of the experts in Braunschweig. Bühler’s WAFA high-speed corrugation machine corrugates fluted rolls at a speed of 120 meters (about 400 feet) per minute in both directions. “The accuracy and the efficiency are impressive. Because it removes less material in the corrugation process, treating roller mills with WAFA extends their lifespan by up to 30 percent,” explains Kasper.

And while the fluted, smooth, or grinded rolls keep on turning around the world and around the clock to produce food, feed, or advanced materials, the dedicated people in Bühler’s dozens of service stations globally continue to ensure that customers can count on the performance of their machinery.

Take a tour through the Braunschweig service station and watch roll refurbishment in action in this video.

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